Introduction: Radiofrequency ablation (RFA) slow pathway modification for catheter ablation of AV nodal reentrant tachycardia (AVNRT) is traditionally performed using a 4mm, non-irrigated (NI) RF ablation catheter. Slow pathway modification using irrigated, contact-force sensing (ICFS) RFA catheters has been described in case reports, but outcomes have not been systematically evaluated. Methods: Acute procedural outcomes of 200 consecutive patients undergoing slow pathway modification for AVNRT were analyzed. An ICFS 3.5mm RFA catheter (ThermoCool SmartTouch STSF, Biosense Webster, Inc.) was utilized in 134 patients, and a 4mm NI RFA catheter (EZ Steer, Biosense Webster, Inc.) was utilized in 66 patients. Electroanatomic maps were retrospectively analyzed in a blinded fashion to determine proximity of ablation lesions to the His region. Results: Baseline characteristics of patients in both groups were similar. Total RF time was significantly lower in the ICFS group compared to the NI group (5.53±4.6 vs. 6.24±4.9 min, p=0.03). Median procedure time was similar in both groups, ICFS 108.0 (87.5-131.5) vs. NI 100.0 (85.0-125.0) min, p=0.2). Ablation was required in closer proximity to the His region in the NI group compared to the ICFS group (14.4 ± 5.9 mm vs, 16.7 ± 6.4 mm, respectively, p=0.01). AVNRT was rendered non-inducible in all patients, and there was no arrhythmia recurrence during follow-up in both groups. Catheter ablation was complicated by AV block in one patient in the NI group. Conclusion: Slow pathway modification for catheter ablation of AVNRT using an irrigated, contact-force sensing RFA catheter is feasible, safe, and may facilitate shorter duration ablation while avoiding ablation in close proximity to the His region.

Incident atrial fibrillation (AF) is common after cavotricuspid isthmus (CTI) dependent atrial flutter (AFL) ablation. Risk factors for development of AF post ablation are not well understood. To identify patients undergoing CTI ablation for AFL most likely to develop AF. We identified 114 patients without history of AF who underwent CTI AFL ablation. We evaluated baseline characteristics, electrophysiology study (EPS) data and echocardiographic data for incidence of AF within 3 years. Incident AF was identified in 46 patients (40%) during 600 + 405 days follow-up. Left atrial volume index (LAVI) was significantly greater in patients who developed AF compared to those that did not (37  12.2 ml/m2 vs 30  13.4 ml/m2, p=.004). EPS data was similar between groups. Area under the receiver operator characteristic curve based on the LAVI for prediction of AF was 0.7 (p = 0.004). Kaplan-Meier estimated incidence of AF was significantly greater in patients with LAVI ≥ 30 ml/m2 than LAVI < 30 ml/m2 (66% vs 27%, p=0.004). Risk of incident AF in patients with LAVI > 40 mL/m2 was similar to that of LAVI 30-40 ml/m2 (67% vs 63%, respectively, p=0.97). In multivariate analysis LAVI remained the sole independent predictor of incidence AF after CTI AFL ablation. LAVI ≥ 30 ml/m2 is associated with significantly increased risk of incident AF following CTI ablation for typical AFL. The utility of elevated LAVI for identifying patients that may benefit from intensified arrhythmia monitoring, or prophylactic AF ablation requires further evaluation.

Background: Catheter ablation procedures for atrial fibrillation (AF) were significantly curtailed during the peak of coronavirus disease 2019 (COVID-19) pandemic to conserve healthcare resources and limit exposure. There is little data regarding peri-procedural outcomes of medical procedures during the COVID-19 pandemic. We enacted protocols to safely reboot AF ablation while limiting healthcare resource utilization. Objective: To evaluate acute and subacute outcomes of protocols instituted for reboot of AF ablation during the COVID-19 pandemic. Methods: Perioperative healthcare utilization and acute procedural outcomes were analyzed for consecutive patients undergoing AF ablation under COVID-19 protocols (2020 cohort; n=111) and compared to those of patients who underwent AF ablation during the same time period in 2019 (2019 cohort; n=200). Newly implemented practices included pre-operative COVID-19 testing, selective transesophageal echocardiography (TEE), utilization of venous closure, and same-day discharge when clinically appropriate. Results: Pre-ablation COVID-19 testing was positive in 1 of 111 patients. There were 0 cases ablation-related COVID-19 transmission, and 0 major complications in either cohort. Pre-procedure TEE was performed in significantly fewer 2020 cohort patients compared to the 2019 cohort patients (68.4% vs. 97.5%, p <0.001, respectively) despite greater prevalence of persistent arrhythmia in the 2020 cohort. Same day discharge was achieved in 68% of patients in the 2020 cohort, compared to 0% of patients in the 2019 cohort. Conclusions: Our findings demonstrate safe resumption of complex electrophysiology procedures during the COVID-19 pandemic, reducing healthcare utilization and maintaining quality of care. Protocols instituted may be generalizable to other types of procedures and settings.

Introduction: Left atrial posterior wall (LAPW) isolation is associated with favorable outcomes for catheter ablation of persistent atrial fibrillation (PEAF). Techniques for LAPW isolation include ablation at the periphery with or without high density ablation within the LAPW. The proportion of LA isolated by the lesion set also varies greatly. The optimal technique to achieve LAPW isolation is not clear. Objective: To assess impact of ablation lesion density within and dimensions of the LAPW isolation region on arrhythmia recurrence in catheter ablation of PEAF. Methods: LAPW lesion density and surface area relative to total LA surface area were calculated using electroanatomic maps of 110 consecutive patients undergoing LAPW isolation for PEAF (CARTO 3, Biosense Webster, Inc.). LAPW isolation was performed at the discretion of 5 experienced operators after voltage mapping. LAPW PV entrance and exit block were confirmed. Arrhythmia recurrence at two years was assessed by Kaplan-Meier analysis. Results: LAPW lesion density ranged from 0% - 99%. The proportion of LA surface area isolated ranged from 35% - 75%. There was no significant difference in arrhythmia-free survival stratified by median LAPW ablation density (31% vs. 27%, p=0.8) or median proportion of electrically-isolated LA surface area (31% vs. 27%, p=0.8%). Voltage map-guided LAPW isolation did not significantly decrease arrhythmia recurrence (29% vs. 28%, p=1). Conclusion: Neither the density of ablation within nor the dimensions of the LAPW isolated region predicted arrhythmia-free survival for catheter ablation of PEAF. Voltage map-guided LAPW isolation resulted in similar ablation efficacy regardless of LA scar burden.

Objective: To compare multiple-procedure catheter ablation outcomes of a stepwise approach versus left atrial posterior wall isolation (LA PWI) in patients undergoing non-paroxysmal atrial fibrillation (NPAF) ablation. Background: Unfavorable outcomes for stepwise ablation of NPAF in large clinical trials may be attributable to pro-arrhythmic effects of incomplete ablation lines. It is unknown if a more extensive initial ablation strategy results in improved outcomes following multiple ablation procedures. Methods: 222 consecutive patients with NPAF underwent first-time ablation using a contact-force sensing ablation catheter utilizing either a stepwise (Group 1, n=111) or LA PWI (Group 2, n=111) approach. The duration of follow-up was 36 months. The primary endpoint was freedom from atrial arrhythmia >30s. Secondary endpoints were freedom from persistent arrhythmia, repeat ablation, and recurrent arrhythmia after repeat ablation. Results: There was similar freedom from atrial arrhythmias after index ablation for both stepwise and LA PWI groups at 36 months (60% vs. 69%, p=0.1). The stepwise group was more likely to present with persistent recurrent arrhythmia (29% vs 14%, p=0.005) and more likely to undergo second catheter ablation (32% vs. 12%, p<0.001) compared to LA PWI patients. Recurrent arrhythmia after repeat ablation was more likely in the stepwise group compared to the LA PWI group (15% vs 4%, p=0.003). Conclusions: Compared to a stepwise approach, LA PWI for patients with NPAF resulted in a similar incidence of any atrial arrhythmia, lower incidence of persistent arrhythmia, and fewer repeat ablations. Results for repeat ablation were not improved with a more extensive initial approach.

Our article reported risk factors for ICD lead failure at our medical center, and we found an elevated risk of ICD lead failure in multiple lead ICD systems implanted via cephalic venous access.(1) Our analysis was prompted by recent literature related to durability of the Linox ICD lead (Biotronik, Inc., Berlin, Germany), and we found similar, elevated risk of ICD lead failure implanted in multiple lead systems via cephalic access in Linox and non-Linox ICD leads. Given the small number of total lead failures in the overall cohort (6 of 660), and the retrospective, single-center nature of our analysis, we reviewed prior Linox ICD lead durability manuscripts for evidence of increased risk of failure in multiple lead ICD systems implanted via cephalic venous access. While no prior manuscript evaluated this specific risk, we did find a trend towards increased risk of lead failure in cohorts with greater proportions of multiple lead systems, and greater proportions of systems implanted via cephalic access, however these variables were included in the analysis in a minority of prior studies.Dr. Maas and colleagues express surprise at the high failure rate when implanting multiple leads in our cohort. We would clarify that we reported ICD lead failure in 4 of the 304 patients in our cohort with multiple ICD leads, and that the frequency of lead failure in multiple lead ICD systems was not statistically significantly different compared to that of single lead ICD systems. In contrast, and surprisingly to us, 3 of 30 patients with multiple lead ICD systems implanted via cephalic access experienced ICD lead failure, and the frequency of ICD lead failure was significantly greater in this group compared to the remaining cohort in Kaplan-Meier survival analyses.Maas and colleagues question the reason for utilization of cephalic access in 18% of patients, hypothesize that suboptimal implantation technique may be responsible for the elevated lead failure rate, and request clarification of lead failure mechanism. We did not systematically collect rationale for venous access technique, and venous access techniques was at the discretion of the implanting physician. Of the 6 lead failures, 3 were related to lead noise, and 3 were related to rising pacing thresholds. Of the three lead failures amongst patients with multiple lead systems implanted via cephalic venous access, 2 were related to lead noise, and 1 was related to a rising pacing threshold. We believe that the lead noise may be related to insulation breach that may be predisposed by lead-lead interactions in the region of the cephalic vein. ICD leads were returned to the manufacturer on an ad hoc basis, and no specific feedback was received from manufacturers related to leads included in our analysis. All implanting physicians were experienced operators, and there were no significant differences in frequency of ICD lead failure by operator. We agree that implantation technique may play an important role in lead failure risk, and our analysis should prompt extra caution when implanting multiple leads via cephalic venous access.Citing the above limitations of our analysis, Dr Maas and colleagues state that it is “too early to abandon cephalic vein access, even for multiple lead systems.” They also review recent literature reporting favorable acute outcomes of ultrasound guided axillary venous access. We agree that our analysis paired with our literature review is best considered hypothesis generating, and we hope that our analysis encourages future studies to consider our findings when selecting variables of interest in ICD lead durability studies. We share Dr. Maas and colleagues’ favorable view of data supporting axillary venous access, particularly in combination with ultrasound guidance. As a result, given the available evidence of acceptable alternative techniques, our practice is to favor axillary venous access during implantation of multiple lead ICD systems, but we would not hesitate to implant via cephalic venous access in the appropriate clinical scenario.References1. Barbhaiya CR, Niazi O, Bostrom J et al. Early ICD lead failure in defibrillator systems with multiple leads via cephalic access. Journal of cardiovascular electrophysiology 2020;31:1462-1469.