1 Degree project, 30 ECTS January 11 2021
Clinical outcomes after using of Rhythmia mapping system in patients with different complex arrhythmias
Version 2
Author: Hanna Ibrahim
School of Medical Sciences Örebro University Örebro Sweden
Supervisor: Dritan Poci, MD PhD
Department of Cardiology Örebro University Hospital Örebro
Word count: Sweden
Abstract: 248 Manuscript: 3500
2 Abbreviations:
ACP: accessory pathway ADD: anti arhythmic drugs AF: atrial fibrillation AFL: atrial flutter
ARVC: arrhythmogenic right ventricular cardiomyopathy EAT: ectopic atrial tachycardia
ECG: electrocardiogram EP: electrophysiological
ICD: implantable cardioverter-defibrillator SR: sinus rhythm.
PV: pulmonary vein
PVC: premature ventricle complex USÖ: Örebro university hospital VT: ventricle tachycardia
3 Abstract:
Background: Rhythmia is a novel mapping system of cardiac arrhythmias, it utilizes a multielectrode catheter, Orion. Together these two instruments generate high accurate maps of the cardiac chamber which facilitate the identification of arrythmia focus and its ablation. Objective: our aim of this study was to evaluate the safety and feasibility of the Rhythmia system, mid-term recurrence rate and the predictors of recurrence from intervention and patients related factors. Methods: this was a retrospective cohort analysis on patients who underwent cardiac ablation with Rhythmia system at Örebro University Hospital between October 2017 and March 2020. The patients were followed-up to evaluate the recurrence. Results: 62 ablation procedures were included, premature ventricular contraction 20, atrial fibrillation 19, ectopic atrial tachycardia 10, ventricular tachycardia 6, atrial flutter 5 and accessory pathways 2. Rhythmia was feasible with 100% technically successful procedures. It had also low complications risk, with an overall 6.5% complications rate. Over a mean follow up of 5.1 months (Range 1-12), 59% of patients got recurrence. The highest recurrence rate of 75% was observed in the premature ventricular complex group. None of all studied variables showed any statistically significance association with the recurrence of the most three encountered arrhythmias. Conclusion: the use of Rhythmia was feasible and relatively safe. The recurrence rate of arrhythmias after using Rhythmia was high, and no reliable predictors could be found. However, there was a trend that atrial fibrillation which required long total procedure time and long fluoroscopy time had higher risk to recur.
Keywords:
Cardiac arrhythmias, Radiofrequency ablation, Rhythmia mapping system, Electro-anatomical cardiac maps, Ablations outcomes.
4 Introduction:
Cardiac arrhythmias are common diseases in the human population. They are a big risk factor for cardiac death and for other events such as heart failure and embolic stroke, which are closely associated with atrial fibrillation (AF). The treatment of cardiac arrhythmias has been constantly evolving in the last few decades. Current treatment options include: antiarrhythmic drugs, defibrillation, pacemaker implantation and radiofrequency cardiac ablation [1–3]. Radiofrequency ablation as treatment of cardiac arrhythmias has developed since the late 1980s and has gained more popularity in the last decade. Initially, cardiac ablation was only used to treat accessory pathways arrhythmias such as Wolff-Parkinson-White syndrome and atrioventricular nodal reentry. However, radiofrequency ablation is now being used more frequently as a curative treatment of both atrial and ventricular arrhythmias [4,5]. Currently it has even become the first line treatment for the most of complex arrhythmias [6]. However, for this treatment option to be more successful, it needs an electro-anatomical map of the cardiac chamber in which the arrhythmia initiates. This map facilitates the identification of the certain arrhythmia focus and later its ablation. This electro-anatomical map shows the pattern of electrical activation or impulse distribution in a chamber, through the recording of the electrical signals “endocardial electrograms” from different areas in the cardiac chamber during a certain rhythm, sinus or not. A cardiac mapping system with a cardiac mapping catheter are used to collect required data mentioned above. Conventional mapping systems and mapping catheters acquired each electrogram through a manual point‐by‐point method. With this method the physician needs to relocate the catheter to register a single new electrogram. This method requires long mapping time and generates maps with low point density which lacks high resolution [7–10].
Rhythmia (Rhythmia©, Boston Scientific, Cambridge, MA, USA) is a novel automatically annotating ultra-high density mapping system. It is integrated with a minibasket multielectrode mapping catheter (IntellaMap Orion©, Boston Scientific, Cambridge, MA, USA) to generate a three- dimensional high-density electro-anatomical map of different cardiac chambers. The Rhythmia system along with Orion catheter generate high density electro-anatomical maps by collecting impedance-based data and magnetic field data together with the electrical activity data from numerous points in the cardiac chamber [9,11,12]. Rhythmia and Orion acquire and annotate many more local electrograms than the manual point-by-point mapping system and therefore they generate rapidly more accurate maps [13]. The Orion catheter with its 64 small and closely spaced electrodes, has a crucial role in generating these accurate maps faster and
5 with a higher resolution than conventional catheters with a single or a few electrodes, as it can acquire up to 64 electrograms at the same time[9,14]. The Rhythmia system and Orion catheter have also shown high success, in mapping and ablation of challenging arrhythmias, such as scar-related arrhythmias and arrhythmias after non-complete ablation. This success is due to the Orion catheter spherical shape and its many small electrodes in addition to Rhythmia’s automated annotating system which can deal with anatomical problems and generate high density maps [15–17].
Rhythmia’s safety and feasibility for mapping of different arrhythmias have been studied and evaluated in previous studies, which have shown the role of Rhythmia mapping system in the successful, safe and feasible treatment of these arrhythmias [11,18–20]. To date, our hospital is the only facility that offers mapping with Rhythmia system in all of Scandinavian. The aim of this study was to evaluate the clinical outcomes of Rhythmia mapping system’s on safety and feasibility. Additionally, we aim to evaluate the recurrence rate of the three most encountered arrhythmias and evaluate the predictors of recurrence from intervention and patient related factors.
Methods:
Study population
The electrophysiological (EP) laboratory at Heart-Lung-Clinical Physiology Department, at Örebro University Hospital has been using Rhythmia and Orion catheter in the mapping of complex cardiac arrhythmias since the late of 2017. This retrospective study included patients treated by radiofrequency ablation for complex cardiac arrhythmias in the EP-laboratory between October 2017 and March 2020. To be included the mapping processes before the ablation have to be done by the Orion mapping catheter, a minibasket multielectrode mapping catheter and the Rhythmia mapping system. Complex cardiac arrhythmias were defined as atrial fibrillation (AF), atrial flutter (AFL), ectopic atrial tachycardia (EAT), premature ventricular contractions (PVC), ventricular tachycardia (VT) and accessory pathway arrhythmias (ACP).
Clinical Data
Patient data needed to answer the study questions were collected from the health information system of Örebro hospital, Kliniska Portalen. The collected data were patient's name, age, sex,
6 county, arrhythmias diagnosis, electrocardiogram test before and after ablation, medications before ablation, echocardiography data before ablation, ablations date and ablations procedure information. Ablations information includes radiofrequency energy application (joule), radiofrequency time (minutes), procedure total time (minutes), fluoroscopic time (minutes), fluoroscopic dose (cGycm2) and whether the procedure was index ablation or a redo ablation. Catheter Ablation Procedure
The procedure was performed on uninterrupted oral anticoagulation with any of NOAC-agents in patients with atrial fibrillation or flutter, and at least four weeks before ablation. Real‐time 3D electroanatomic mapping was performed as described above using Rhythmia mapping system. All patients underwent echocardiography before catheter ablation and patients with AF even transesophageal. Computer tomography was used before ablation in patients with AF and magnetic resonance imaging was used in those with VT. The procedure end point was (a) the absence of pulmonary vein (PV) signals for at least 15 minutes during sinus rhythm (SR) in patients with AF, (b) the termination of arrhythmia in those with EAT and (c) the termination of arrhythmia in those with PVC, and (d) abolition of arrhythmogenic signals in patients with VT.Direct current cardioversion was performed when needed. After ablation, all patients were observed on telemetry monitoring on the wards, usually for 24 hours. Anti arhythmic drugs (AAD) and oral anticoagulation were continued for three to six months after the ablation and then reevaluated. Withdrawal of AADs was guided by symptoms and intermittent ECG monitoring rather than the actual arrhythmia burden.
Safety and feasibility:
Safety was determined by collecting of all adverse serious complications during hospitalization and the first month after ablation. Serious complications were defined as cardiac death, pericardial tamponade, esophageus damage, pericardial effusion, severe bleeding requiring blood transfusion, cerebral embolism, intracerebral hemorrhage and pulmonary embolism. Other complications related to the procedure, such as; pseudoaneurysm in the puncture site and deep vein thrombosis were also collected for the evaluation of safety. The complications rate if possible, would be compared to the rate from the Swedish national quality registry of catheter ablation.
Feasibility was defined as the operators had been able to perform a technically successful mapping of the arrhythmias and the ablation treatment was given. This means generating of
7 useful maps without the need to switch to another mapping system during the procedure due to technical failure or issues inherent to the system.
Follow-up
Patient who received their ablation between October 2017 and September 2019 were followed up to a year after the procedure date. Patients who received their ablation between October 2019 and March 2020 were followed up until the end of September 2020. Some patients had definite follow-up visits after 3, 6, and 12 monthseither at our hospital or in their home clinics. All patients were asked to contact us in the case of complications and those from Örebro County were asked to contact us for symptoms relapse in addition. Data from follow-up visits in home clinics were reported to us via the respective clinics. The aim of following up was to detect any documented recurrence of any arrhythmias and occurrence of side effects or complications. All registered health care information, ECG-test, 24‐hour ambulatory Holter monitoring, ECG event recorder monitor test, ICD-control and pacemaker-control after the procedure date were collected. Follow ups ended after the first recurrence event or by the end of the one-year mark. Statistical analyses
Continuous data were expressed as the mean ± SD and range for follow up time. Categorical data were expressed as numbers and percentages. To assess differences in categorical variables among patients in recurrence and no-recurrence groups Fisher’s exact test was performed. Differences in continuous variables were assessed with T-test. Univariate logistic regression analysis was used to determined predictors of arrythmia recurrence in the AF, EAT and PVC groups. The statistical analyses were performed using STATA 16.1 - StataCorp 4905 Lakeway Drive College Station, Texas 77845 USA. An p value < 0.05 was considered statistically significant for each analysis.
Ethical consideration
This study is a quality improvement analysis. The medical records were examined without the consent of the patient of included patients, which goes against the principle of self-determination. However, all patients were coded during the data analysis. The results are presented on group level which make it impossible to identify single patient. The results could increase the knowledge about clinical outcomes after using this new system which will benefit arrhythmia patients in the long run.
8 Results:
A total of 62 cardiac mapping and ablation procedures using Rhythmia mapping system were included in this study. These procedures were performed by two physicians on 61 patients. Of these patients 22 were female, and the mean age was 57.8±11.4 years. Thirty-seven of the total number of patients had undergone a previous ablation procedure and thirty-nine were from Örebro county. Since only one of the patients had the procedure done twice under the study timefor clearer presentation of the results, each procedure was considered as a different patient. Patient baseline clinical demographic and characteristics are summarized in Table 1. PVC ablation was the most performed procedure with a total of 20 procedures. The distribution of treated arrythmia are shown in Figure 1.
Table 1.Baseline clinical characters
Characters ACP EAT PVC AF VT AFL
Patients, n (%) 2 (3.2) 10 (16.2) 20 (32.2) 19 (30.6) 6 (9.8) 5 (8) Male Sex, n (%) 1 (50) 7 (70) 9 (45) 15(79) 5 (83) 3(60) Age (years) 59±19 58±10 53±13 59±10 64±12 62±9 Cardiomyopathy, n (%) 0 (0) 3 (30) 1 (5) 0 (0) 2 (33) 0 (0) ICD/Pacemaker, n (%) 1(50) 5(50) 2(10) 2(10.5) 5(83) 0(0) EF (%) 60 52.5±9.2 51.2±10.6 57.4±6.5 53.3±12.9 55±16.9 LVDD area (mm) 48±2.8 49±5.5 53.5±5.2 51.2±5.1 59.2±13.5 50.8±4.5 LA (cm2) 19.5±3.5 23.8±4.8 20.1±4.2 23±4.5 31±3.5 24.8±7.3 Previous ablation (%) 1(50) 7 (70) 10 (50) 17 (89) 2 (33) 0 (0)
Treatment before ablation Anti-arrhythmic drug (%) 1 (50) 9 (90) 16 (80) 19 (100) 6 (100) 5 (100) Beta blocker, n (%) 0 (0) 8 (80) 13 (65) 15 (79) 6 (100) 5 (100) Cordarone, n (%) 0 (0) 1 (10) 2 (10) 6 (32) 4 (67) 0 (0) Other AA*, n (%) 1 (50) 2 (20) 3 (15) 5 (26) 2 (25) 0 (0) ACE/ARB, n (%) 0 (0) 5 (50) 10 (50) 5 (26) 4 (67) 3 (60) NOAC/WARAN, n (%) 0 (0) 5 (50) 2 (10) 19 (100) 3 (50) 3 (60)
9 Values are n (%) or mean ± Standard Deviation.
N, number; ICD, implantable cardioverter-defibrillator; EF, ejection fraction; LVDD, left ventricular end-diastolic diameter; AA, anti-arrhythmic; ACE, angiotensin-converting enzyme; ARB, Angiotensin receptor blockers; NOAC, Non-Vitamin K antagonist oral anticoagulants.
*Other AA= Other antiarrhythmics such as Tambocor and Multaq.
Figure1:
The distribution of the included ablated arrythmias. Premature complex ablation was the most performed procedures. The ablation of the accessory pathway was the least performed procedure. PVC, premature ventricular complex; AF, atrial fibrillation; EAT, ectopic atrial tachycardia; VT, ventricular tachycardia; AFL, atrial flutter; ACP, accessory pathways.
Feasibility and safety results:
All the 62 procedures (100%) were assessed as technically successful. The physician could generate accurate electro-anatomical maps and ablation was completed in all cases. Procedures characters for all groups are shown in Table 2. The endpoint of the procedure was achieved in all patients in the AFL, ACP, VT and EAT groups, all patients had SR after the ablation. The endpoint was also achieved in all patients of the AF group with the absence of PV signals for at least 15 minutes. On the other hand, only 8 (40%) of the 20 the procedures achieved their endpoint in the PVC group.
There were no deaths reported in the 30-day following period. Only 4 serious events occurred in the 62 procedures; one patient from the EAT group had a serious bleeding at the puncture site that required blood transfusion, one patient from the AF group had a transient ischemic attack, and two patients from the PVC group had serious events; a deep vein thrombosis and a stenosis at the puncture site. The stenosis was detected a few days after the 30-day follow up
ACP 2 EAT 10 PVC 20 AF 19 VT 6 AFL 5
10 Values are n (%) or mean ± Standard Deviation.
N, number; J, joule; RF, radiofrequency; min, minutes; cGy, centigray; cm, centimeter.
and was caused by a thrombosis. The physician correlated this event to the ablation procedure and therefore it included in the safety results. All the 4 (6.5%) adverse events are summarized in Table 2.
Two patients, one from the PVC group and one from the EAT group, had chest pain a few days after the procedure. Cardiac ultrasound showed possibly mild irritation of the pericardium, no exudate was shown. These two patients did not get any treatment therefore these two events were not considered as serious adverse events.
Table 2. Ablation procedures characters
Characters ACP EAT PVC AF VT AFL
Patients, n (%) 2 (3.2) 10 (16.2) 20 (32.2) 19 (30.6) 6 (9.8) 5 (8) Procedure time (min) 165±21 265±112 225±59 227±74 242±55 178±37 RF energy (J) 12801 62693±39273 42741±30412 754234±34746 58139±29706 81662±23749 RF time (min) 9 36±22 26±14 44±20 31±9 45±14 Fluoroscopy dose (cGy ∗ cm2) 284±305 710±193 645±398 645±398 896±226 643±192 Fluoroscopy time (min) 11±9 31±15 41±20 41±20 44±17 26±14 Technical success, n (%) 2 (100) 10 (100) 20 (100) 19 (100) 6 (100) 5 (100) Complications Severe bleeding (1) Deep vein thrombosis (1), Stenosis in the puncture site (1) Transient ischemic attack (1) Follow up:
Not all patients had a regular follow up. Only fifty-one of our population had at least one registered follow up after the procedure date. Hence, we only included these 51 patients in the follow up statistic. We followed up our population for a mean of 5.1 months (Range 1-12
11 months). Thirty patients (59%) got recurrence under this time. The most three encountered arrhythmiaswhich we focused on were PVC, AF and EAT.
In the PVC group 16 of 20 patients had at least one registered follow up. They were followed up for mean of 3.8 months (range 1-12 months) 12 (75%) of them got recurrence. In the AF group 15 of 19 patients had at least one registered follow up during a mean of 6.9 months (range 2-12 months) 7 patients (47%) got recurrence. In the EAT group 9 of 10 patients had at least one registered follow up. They were followed up for a mean of 4.7 months (Range 1-12 months), 6 patients (67%) got recurrence. Recurrence data is summarized in Table 3.
Predictors of recurrence:
Patients in the three arrhythmias groups were divided into recurrence and no recurrence groups in order to find potential differences and evaluate potential recurrence predictors. T-test and Fisher’s exact test showed that there were no significant differences in all studied clinical and procedural characters between the patients with recurrence and without recurrence in the PVC, EAT and AF groups. Table 3.
Univariant logistic regression analysis were also performed to evaluate if any variables in table 4, could predict the recurrence. This analysis couldn’t show any statistically significant correlation between arrythmias recurrence and all studied variables. There was a slightly positive association between the total procedure time and fluoroscopy time and the recurrence of atrial fibrillation. However, this slightly association was not statistically significant. Table 4. Table 3. Comparison between Recurrence and No Recurrence groups
Characters Recurrence No PVC Recurrence P No Recurrence EAT Recurrence P No Recurrence AF Recurrence P N (%) 4 (25) 12 (75) 3 (33.3) 6 (66.7) 8 (53.3) 7 (46.7) Age, y 44.5 ± 7.9 53.1 ± 13.2 0.2 63.3 ± 10.1 58.3 ± 7.3 0.4 62.3 ± 7.2 53.4 ± 11.9 0.1 Sex, male n(%) 2 (50) 4 (33) 0.6 3 (100) 3 (50) 0.5 8 (100) 5 (71) 0.2 LA area, cm2 18±1.7 21.5±5 0.3 23.3±2.9 24±6.2 0.9 22.6±3.9 21.5±4.9 0.6 RA area, cm2 17±1.4 17±4.2 1.0 19.3±3.8 27±10.1 0.3 21.6±4.6 21.2±4.4 0.9 LVDD, mm 52.7±4.2 53.2±5.9 0.9 52.3±3.5 48±6.2 0.3 52.5±3.3 50.5±4.7 0.4 EF (%) 53±9.5 50.7±12.1 0.7 50±8.7 53.3±10.8 0.7 58.1±3.7 59.3±4.5 0.6 RF energy, J 33864 ± 23882 47878± 36608 0.5 42394 ± 10522 72843 ± 45306 0.3 75553 ± 39158 76995 ± 30820 0.9
12 RF time, min 23.3 ± 6.1 27.8 ± 17.4 0.7 27 ± 8.7 40.3 ± 25.8 0.4 42.5 ± 23.1 46.9 ± 15.9 0.7 Procedure time, min 198.8 ± 22.5 225.8 ± 72.2 0.5 193.3 ± 45.1 265 ± 96.4 0.3 200 ± 52.1 277.1 ± 84.6 0.05 Fluoroscopy time, min 25.3 ± 13.1 44.5 ± 22 0.1 28 ± 20.7 34 ± 13.9 0.6 28.6 ± 12.5 45.6 ± 18.9 0.058 Fluoroscopy dose, (cGy ∗ cm2) 417±171.6 670.9±439. 8 0.3 557.3±253. 7 733.3±82.1 0.1 830.5±510. 1 1007±681. 2 0.6 ‘
Table 4. Predictors of arrhythmias recurrence
Characters
PVC
Odds ratio 95% (CI) P
EAT
Odds ratio 95%(CI) P
AF
Odds ratio 95% (CI) P Age 1.07 (0.95 - 1.2) 0.2 0.90 (0.74 - 1.12) 0.4 0.9 (0.79 - 1.03) 0.1 Sex 2.00 (0.20 - 19.9) 0.6 _ _ _ _ LA area 1.25 (0.84 - 1.88) 0.3 1.03 (0.77 - 1.38) 0.8 0.93 (0.72 - 1.22) 0.6 RA area 13.8 (0.66 - 1.5) 1.0 1.20 (0.87 - 1.66) 0.3 0.97 (0.75 - 1.26) 0.8 LVDD 1.02 (0.8 - 1.29) 0.9 0.79 (0.5 - 1.2) 0.3 0.86 (0.63 - 1.2) 0.3 EF 0.98 (0.88 - 1.1) 0.7 1.04 (0.89 - 1.2) 0.6 1.08 (0.82 - 1.4) 0.6 RF energy 1.00 (0.99 - 1.0) 0.5 1.00 (0.99 - 1.0) 0.3 3.70 (0.99 - 1) 0.9 RF time 1.02 (0.92 - 1.12) 0.7 1.04 (0.95 - 1.4) 0.4 1.01 (0.96 - 1.07) 0.7 Procedure time 1.01 (0.98 - 1.04) 0.5 1.03 (0.98 - 1.07) 0.2 1.02 (0.99 - 1.04) 0.075 Fluoroscopy time 1.09 (0.98 - 1.22) 0.1 1.03 (0.93 - 1.14) 0.6 1.09 (0.98 - 1.2) 0.09 Fluoroscopy dose 1.00 (0.99 - 1.01) 0.3 1.00 (0.99 - 1.03) 0.3 1.00 (0.99 - 1.0) 0.6 Values are n (%) or mean ± Standard Deviation.
LA, left atrium; RA, right atrium; LVDD, left ventricular end-diastolic diameter; EF, ejection fraction; RF, radiofrequency; P, p-value; cGy, centigray; cm, centimeter.
LA, left atrium; RA, right atrium; LVDD, left ventricular end-diastolic diameter; EF, ejection fraction; RF, radiofrequency; P, p-value.
13 Discussion:
To our knowledge, this is the first study that has evaluate the safety and feasibility of Rhythmia system in Sweden. This study found that Rhythmia was feasible for mapping procedures during radiofrequency ablation of different complex arrhythmias with 100% technically success. Lackermair et al. had similar definition of feasibility in his study which was done on larger group of patients with different complex atrial and ventricular arrythmias. Lackermair also had 100% feasibility [11]. Thirty-seven patients in the present study had previously undergone radiofrequency ablation. Previous ablation often generated scar-tissue which is more complex to map than healthy tissue and it can reconnect and initiate new complex arrhythmias. Although there was a high number of redo procedures in this study, Rhythmia had 100% feasibility. Other studies with larger cohort showed that Rhythmia system was good in mapping of recurrent arrhythmias and arrhythmias caused of previous ablation [16,21,22].
The results showed that Rhythmia system had low complications risk during the mapping of complex arrhythmias in all cardiac chambers. Under the first month after procedures date only 4 (6.5%) out of 62 patients reported adverse complications. The total complications rate was higher than the rate in the Swedish national quality registry of catheter ablation under 2019. This registry includes all performed ablation procedures in Sweden using different mapping system. The national registry had a 1.3% complications rate for all ablation procedures. It is difficult to compare data without grouping them according to the diagnosis. However, this was hard to achieve with such a small cohort like ours. Therefore, 42% of our procedures were performed in the ventricle, while only 7% of the procedures in the registry were performed in the ventricle chamber. This was reflected in the complications rate in the national registry for the ventricle procedures being 5.1% in PVC group and 4.9% on the VT group [23]. G. Hindricks et al. evaluated the safety of Rhythmia system along with Orion catheter on a bigger cohort in a multicenter study. The rate of complication related to procedure or device was 4% which is close to the results of the present study [24].
Mid-term follow up showed, as expected, different recurrence rates in different arrhythmia groups. The highest recurrence rate was observed in the PVC group. This high rate probably depends on various reasons. It may partially be due to both the nature of the PVC arrhythmia and our definition of the its recurrence. PVC is a complex arrhythmia which can be polymorphic in up to 50% of cases, and physicians used to focus on the predominant PVC, sometimes called as clinical PVCs, during the radiofrequency ablation [25]. Therefore, other studies which evaluate the long and med-term success of the PVC ablation, defined it as a decrease by ≥80%
14 of the predominant PVC burden. The long and mid-term success in these studies ranged between 70-75% [25,26]. While, any documented single premature ventricular beat was counted as a recurrence in this study. No patients with recurrent PVC got a repeat procedure during the follow up time, this can be evidence of decreased PVC burden by time and thus symptom decreased.
The recurrence rate in the EAT group was also high at 67%. Other studies showed varying recurrence rates from 37% to 53% after catheter ablation with different mapping systems [27– 29]. The high recurrence rate in present study can partially be explained by the high number of patients with cardiomyopathies in the EAT group. Three of 6 patients who had a recurrence in this group had a cardiomyopathy; one patient with Tetralogy of Fallot and two patients with Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC). Several studies showed that both of Tetralogy of Fallot and ARVC are associated with serve and difficult to treat atrial tachycardias [30–33]. Furthermore, 5 out of the 6 patients with EAT recurrence had got at least one radiofrequency ablation before they got mapping and ablation with Rhythmia system which is indicative of the severity and complexity of the arrhythmias in this group.
The recurrence rate in the AF group was 47%. It is noteworthy that 87% of patients in this group had been previously ablated for the same arrhythmias. The recurrence rate of AF after using the Rhythmia system in patients with previous failed radiofrequency ablation have been evaluated in three previous studies and were 16%, 41% and 47% respectively [21,22,34]. Recurrence often caused by the electrical reconnection between the atrium and the pulmonary veins after previous procedure. There was no clear reason for the differences in the recurrence rates among these studies. However, the results of this study were comparable to previous studies using Rhythmia.
The present study investigated whether any clinical or procedural variable could be independent predictor(s) for recurrence in the three arrhythmia groups. No variables showed any statistically significant results. Although, there was a trend of association between long fluoroscopy time and long total procedure time and the recurrence in the AF group. This association can indicate that arrhythmias that were more complex and difficult to map had a higher risk to recur. The previous studies that had evaluated the predictors of AF recurrence after catheter ablation showed that age, arrythmia duration, overweight, structural heart diseases and LA volume were some of the clinical characters which could predict AF recurrence [35,36].Shim et al. evaluated the procedural parameters which could indicate AF recurrence after radiofrequency ablation. Shim’s results showed that ablation time, fluoroscopy time and total procedural time were
15 longer in the AF recurrence group. Univariate logistic regression analysis also found that long energy delivery time and long fluoroscopy time were predictors of AF recurrence. Multivariate analysis yielded the long energy delivery time as an independent risk factor for AF recurrence in Shim’s study [37].
Limitations:
The mainly limitation in this study is the absence of a control group of patients treated with another mapping system. This group could be used to determine Rhythmias’ safety, feasibility, and recurrence rate in relation to the control mapping system. However, this study included all patients who underwent a mapping procedure with Rhythmia system, independently of the arrhythmia type, and in our laboratory the physicians often use only the Rhythmia system to map complex arrhythmias. Therefore, it was difficult to find matched control groups. The second limitation is the relatively small cohort. This could have greatly affected the statistical results. It could be one of the reasons why we were unable to detect any differences in the clinical variables between patients with and without recurrence. We believe that the slightly none statistically significant association between the long-time procedure and long-time fluoroscopy that we observed would be truly statistically significant with a larger cohort. Moreover, the use of AA drugs could greatly affect arrhythmia recurrence. During the retrospective follow-ups, the knowledge on whether AA drugs were continued after ablations is inadequate. This is also due to the follow-up visits, which for most of patients were done at their home hospitals, and at sometimes, we were only able to obtain information on patients’ rhythms.
Nevertheless, the study’s observation could generate a lot of knowledge on the safety and effectiveness of Rhythmia mapping system during RF-ablation therapy in patients with complex arrhythmia when the alternative treatment choices are limited.
Conclusion:
The EP laboratory at USÖ has been using Rhythmia mapping system along with Orion mapping catheter during the radiofrequency ablation procedure of complex arrythmias since the late of 2017. This study demonstrated that the use of Rhythmia system was feasible and relatively safe with low complications risk during the mapping of all the included 62 complex arrythmias. The recurrence rate of different arrhythmias and specifically the PVC after using Rhythmia was
16 high. No clinical or procedural variables could indicate the recurrence of the arrhythmias in the present study, although long procedure time and long fluoroscopy time might predict AF recurrence in a larger cohort. More studies with larger cohort in the future, and a better definition of PVC recurrence after RF-ablation, are needed in order to generate specific data regarding to prediction of arrhythmias recurrences and the recurrence rate.
References:
1. Fu D. Cardiac Arrhythmias: Diagnosis, Symptoms, and Treatments. Cell Biochem Biophys 2015;73:291–6.
2. Andrade JG, Rivard L, Macle L. The Past, the Present, and the Future of Cardiac Arrhythmia Ablation. Can J Cardiol 2014;30:S431–41.
3. Chugh SS, Blackshear JL, Shen W-K, Hammill SC, Gersh BJ. Epidemiology and natural history of atrial fibrillation: clinical implications. J Am Coll Cardiol 2001;37:371–8. 4. Stevenson WG, Ellison KE, Lefroy DC, Friedman PL. Ablation Therapy for Cardiac
Arrhythmias. Am J Cardiol 1997;80:56G-66G.
5. Hosseini SM, Rozen G, Saleh A, Vaid J, Biton Y, Moazzami K, et al. Catheter Ablation for Cardiac Arrhythmias: Utilization and In-Hospital Complications, 2000 to 2013. JACC Clin Electrophysiol 2017;3:1240–8.
6. Page RL, Joglar JA, Caldwell MA, Calkins H, Conti JB, Deal BJ, et al. 2015
ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia: A Report of the American College of Cardiology/American Heart
Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol 2016;67:e27–115.
7. Jones DG, McCready JW, Kaba RA, Ahsan SY, Lyne JC, Wang J, et al. A multi-purpose spiral high-density mapping catheter: initial clinical experience in complex atrial
arrhythmias. J Interv Card Electrophysiol 2011;31:225.
8. Smeets Joep L. R. M., Ben-Haim Shlomo A., Rodriguez Luz-Maria, Timmermans Carl, Wellens Hein J. J. New Method for Nonfluoroscopic Endocardial Mapping in Humans. Circulation 1998;97:2426–32.
9. Ptaszek LM, Chalhoub F, Perna F, Beinart R, Barrett CD, Danik SB, et al. Rapid acquisition of high-resolution electroanatomical maps using a novel multielectrode mapping system. J Interv Card Electrophysiol 2013;36:233–42.
10. Issa ZF, Miller JM, Zipes DP. 5 - Conventional Intracardiac Mapping Techniques [Internet]. In: Issa ZF, Miller JM, Zipes DP, editors. Clinical Arrhythmology and Electrophysiology (Third Edition). Philadelphia: Content Repository Only!; 2019 [cited 2020 Sep 26]. p. 125–54. Available from:
17 11. Lackermair K, Kellner S, Kellnar A, Riesinger LM, Wakili R, Sinner MF, et al. Initial
single centre experience with the novel Rhythmia© high density mapping system in an all comer collective of 400 electrophysiological patients. Int J Cardiol 2018;272:168–74. 12. Borlich M, Sommer P. Cardiac Mapping Systems: Rhythmia, Topera, EnSite Precision,
and CARTO. Card Electrophysiol Clin 2019;11:449–58.
13. Rottner L, Metzner A, Ouyang F, Heeger C, Hayashi K, Fink T, et al. Direct Comparison of Point‐by‐Point and Rapid Ultra‐High‐Resolution Electroanatomical Mapping in Patients Scheduled for Ablation of Atrial Fibrillation. J Cardiovasc Electrophysiol 2017;28:289–97.
14. Kosiuk J, Hilbert S, John S, Bertagnolli L, Hindricks G, Bollmann A. Preliminary experience with high-density electroanatomical mapping for ablation of atrial fibrillation – Comparison of mini-basket and novel open irrigated magnetic ablation catheter in consecutive patients. Int J Cardiol 2017;228:401–5.
15. Anter E, Tschabrunn CM, Contreras-Valdes FM, Li J, Josephson ME. Pulmonary vein isolation using the Rhythmia mapping system: Verification of intracardiac signals using the Orion mini-basket catheter. Heart Rhythm 2015;12:1927–34.
16. Anter E, McElderry TH, Contreras-Valdes FM, Li J, Tung P, Leshem E, et al. Evaluation of a novel high-resolution mapping technology for ablation of recurrent scar-related atrial tachycardias. Heart Rhythm 2016;13:2048–55.
17. Xue Y, Liu Y, Liao H, Zhan X, Fang X, Deng H, et al. Evaluation of Electrophysiological Mechanisms of Post-Surgical Atrial Tachycardias Using an Automated
Ultra-High-Density Mapping System. JACC Clin Electrophysiol 2018;4:1460–70.
18. Viswanathan K, Mantziari L, Butcher C, Hodkinson E, Lim E, Khan H, et al. Evaluation of a novel high-resolution mapping system for catheter ablation of ventricular
arrhythmias. Heart Rhythm 2017;14:176–83.
19. Schaeffer B, Hoffmann BA, Meyer C, Akbulak RÖ, Moser J, Jularic M, et al. Characterization, Mapping, and Ablation of Complex Atrial Tachycardia: Initial Experience With a Novel Method of Ultra High-Density 3D Mapping. J Cardiovasc Electrophysiol 2016;27:1139–50.
20. Sohns C, Saguner AM, Lemes C, Santoro F, Mathew S, Heeger C, et al. First clinical experience using a novel high-resolution electroanatomical mapping system for left atrial ablation procedures. Clin Res Cardiol Off J Ger Card Soc 2016;105:992–1002.
21. Ikeda Y, Kato R, Mori H, Tsutsui K, Goto K, Nagase T, et al. Impact of high-density mapping on outcome of the second ablation for atrial fibrillation. J Interv Card Electrophysiol [Internet] 2020 [cited 2020 Nov 15]; Available from:
https://doi.org/10.1007/s10840-020-00716-y
22. Masuda M, Asai M, Iida O, Okamoto S, Ishihara T, Nanto K, et al. Comparison of ablation outcomes of the second ablation procedure for recurrent atrial fibrillation using an ultra-high-resolution mapping system and conventional mappings system. Clin Cardiol 2019;42:966–73.
18 23. Holmqvist F. Nationellt kvalitetsregister för kateterablation 2019 Årsrapport [Internet].
Stockholm: Aablationsregistret; 2020 [cited 2020 Nov 15]. Available from: https://www.ucr.uu.se/kateterablation/component/edocman/2019-arsrapport-2
24. Hindricks G, Weiner S, McElderry T, Jaïs P, Maddox W, Garcia-Bolao JI, et al. Acute safety, effectiveness, and real-world clinical usage of ultra-high density mapping for ablation of cardiac arrhythmias: results of the TRUE HD study. Europace 2019;21:655– 61.
25. Predictors of Outcome After Catheter Ablation of Premature Ventricular Complexes - BASER - 2014 - Journal of Cardiovascular Electrophysiology - Wiley Online Library [Internet]. [cited 2020 Nov 20]; Available from:
https://onlinelibrary-wiley-com.db.ub.oru.se/doi/full/10.1111/jce.12400
26. Latchamsetty R, Yokokawa M, Morady F, Kim HM, Mathew S, Tilz R, et al. Multicenter Outcomes for Catheter Ablation of Idiopathic Premature Ventricular Complexes. JACC Clin Electrophysiol 2015;1:116–23.
27. Maury P, Champ-Rigot L, Rollin A, Mondoly P, Bongard V, Galinier M, et al.
Comparison between novel and standard high-density 3D electro-anatomical mapping systems for ablation of atrial tachycardia. Heart Vessels 2019;34:801–8.
28. Baker BM, Lindsay BD, Bromberg BI, Frazier DW, Cain ME, Smith JM. Catheter
ablation of clinical intraatrial reentrant tachycardias resulting from previous atrial surgery: localizing and transecting the critical isthmus. J Am Coll Cardiol 1996;28:411–7.
29. Triedman JK, Bergau DM, Saul JP, Epstein MR, Walsh EP. Efficacy of Radiofrequency Ablation for Control of Intraatrial Reentrant Tachycardia in Patients With Congenital Heart Disease. J Am Coll Cardiol 1997;30:1032–8.
30. Ezzat VA, Ryan MJ, O’Leary J, Ariti C, Deanfield J, Pandya B, et al. Radiofrequency ablation of atrial tachyarrhythmias in adults with tetralogy of Fallot – predictors of success and outcome. Cardiol Young 2017;27:284–93.
31. Roos-Hesselink Jolien, Perlroth Mark G., McGhie Jacky, Spitaels Silja. Atrial
Arrhythmias in Adults After Repair of Tetralogy of Fallot. Circulation 1995;91:2214–9. 32. Ablation of atrial tachyarrhythmias late after surgical correction of tetralogy of Fallot:
long-term follow-up [Internet]. [cited 2020 Nov 20]; Available from: https://www.mp.pl/kardiologiapolska/issue/article/14672
33. Kikuchi N, Shiga T, Suzuki A, Hagiwara N. Atrial tachyarrhythmias and heart failure events in patients with arrhythmogenic right ventricular cardiomyopathy. Int J Cardiol Heart Vasc [Internet] 2020 [cited 2020 Nov 20];31. Available from:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7653060/
34. Siebermair J, Neumann B, Risch F, Riesinger L, Vonderlin N, Koehler M, et al. High-density Mapping Guided Pulmonary Vein Isolation for Treatment of Atrial Fibrillation - Two-year clinical outcome of a single center experience. Sci Rep [Internet] 2019 [cited 2020 Nov 22];9. Available from:
19 35. Yokokawa M, Oral H, Chugh A. Predictors of Recurrence After Radiofrequency Ablation
of Persistent Atrial Fibrillation. J Atr Fibrillation [Internet] 2012 [cited 2020 Nov 23];5. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5153209/
36. Cai L, Yin Y, Ling Z, Su L, Liu Z, Wu J, et al. Predictors of late recurrence of atrial fibrillation after catheter ablation. Int J Cardiol 2013;164:82–7.
37. Shim J, Joung B, Park JH, Uhm J-S, Lee M-H, Pak H-N. Long duration of radiofrequency energy delivery is an independent predictor of clinical recurrence after catheter ablation of atrial fibrillation: Over 500 cases experience. Int J Cardiol 2013;167:2667–72.
20
Örebro, Sweden, 2020-12-30
Cover letter
Dear Editor of International Journal of Cardiology,
We enclose our manuscript entitled “Clinical outcomes after using of Rhythmia mapping system in patients with different complex arrhythmias”. Please, consider this manuscript for publication in the International Journal of Cardiology.
We investigate the safety and feasibility of the novel mapping system, Rhythmia, using in complex cardiac arrhythmias. We also evaluate the mid-term recurrence rate after using this system and the potential predictors of arrhythmia recurrence. Along with we realized
Rhythmia mapping system as relatively safe and useful system for generating of accurate electro-anatomical maps, we found that the recurrence rate after using this system is high. We also found that the long procedure time and long fluoroscopy time were slightly associated with the recurrence of atrial fibrillation in our study. This association was not statistically significant.
We believe that our findings will generate some more knowledge on safety and feasibility issues of Rhythmia mapping system. They will also encourage for more studies to ensure the high recurrence rate and the potential recurrence predictors.
Yours sincerely, Hanna Ibrahim BM
Faculty of Medicine and Health Örebro University
Örebro Sweden
21 Etisk reflektion
Den här studien utvärderade en ny diagnostik och behandlingsmetod som används vid ablationsbehandling av hjärtarytmier på kardiologikliniken, USÖ, Örebro. Studien är ett retrospektivt kvalitetssäkringsprojekt och har utförts utan att hämta några samtycken från inkluderade patienter. Forskaren har granskat patienternas journaluppgifter för att utvärdera de kliniska resultateten efter användning av den nya metoden. De här kliniska uppgifterna är känsliga och dess granskning utan samtycke från patienten kan betraktas som kränkande handling. Dessutom så finns det hela tiden en liten risk för informationsläckage som kan innebära en psykisk påfrestning på de inkluderade. Därför har projektet planerats och utförts på ett sätt som minimerar risken för information läckage samt identifiering och kräkning av inkluderade patienter. Projektet har fått godkännande av klinikens verksamhetschef, diarieförts och registrerat i platina. När det gäller listan på inkluderade patienter så har den förvarats i ett låst skåp på kardiologkliniken, hos huvudforskare. Alla patienter var kodade vid skapandet av Excel-filer som sparrade sedan på klinikens hemdirektory. Forskare visste från början att denna forskning inte skulle innebära några fysiska eller psykiska ingrepp på inkluderade patienter. Studien har också utförts inom ramen för studenthandlingsprojekt och kommer inte att publiceras i någon tidskrift. Resultatet från detta projekt skulle inte ändra vården för de inkluderade patienterna, dock kommer det förmodligen att öka kunskapen kring säkerhet, användarvänlighet samt återfallsfrekvensen av det nya systemet. Dessa nya kunskaper kommer att gynna arytmipatienter på sikt genom att erbjuda dem en säker och användarvänlig diagnostik och behandlingsmetod.
22 Populärvetenskaplig sammanfattning
Hjärtrytmrubbningar är ett stort hälsoproblem därför har behandlingen för dessa sjukdomar utvecklats ständigt. En av de senaste och mest effektiva behandlingsmetoder är radiofrekvensablation. Man använder radiovågor för att bränna hjärt-vävnader som startar och sprider dessa rytmrubbningar. Innan ablationsbehandlingen ges måste man skapa en elektronisk och anatomisk karta av hjärtat med hjälp av ett kartläggning system. Denna karta underlättar identifieringen av det specifika rytmrubbnings fokuset och senare dess ablation. Rhythmia är ett nytt och automatisk kartläggning system som introducerades i Sverige i slutet av 2017. Syftet med denna studie var att utvärdera säkerheten och användarvänlighet av Rhythmia. Vi studerade också förekomsten av återfall och eventuella prediktorer för rytmrubbningsåterfall. Metod vi inkluderade alla 62 patienter som fick ablation behandling med hjälp av Rhythmia system sedan den introducerades på vårt sjukhus fram till slutet av september 2020. Säkerheten var definierat som avsaknad av svåra komplikationer till exempel blödning, stroke med mera.
Användarvänligheten var definierat som en teknisk lyckad procedur genom bildning av tydliga
elektriska och anatomiska kartor.
Resultat och konklusion: Rhythmia system var användarvänlig då alla procedurer bedömdes som teknisk lyckade. Systemet var också relativt säker, 4 patienter fick komplikationer, ingen av dem var dödlig eller livshotande. Vi följde våra patienter i cirka 5 månader, under denna tid 59% fick återfall vilket bör diskuteras med hänsyn till komplexiteten av hjärtrytmrubbningen. Vi kunde inte hitta några variabler som kan förutsäga återfall. Studier med större antal patienter och längre uppföljningstid skulle behövas i framtiden för att säkerställa återfallsfrekvensen och definiera några återfall prediktorer.
