Faculty Bibliography

BACKGROUND:Leadless pacemakers (LPs) avoid the lead- and pocket-related complications of transvenous systems, but they pace exclusively from the right ventricle (RV), and chronic RV pacing carries a recognized risk of pacing-induced cardiomyopathy (PICM). Whether implant location within the RV, a potentially modifiable factor, contributes to this risk has not been established. METHODS:Patients undergoing LP implantation with ≥50% RV pacing, pre-and post-procedural echocardiograms, and post-implant 3-dimensional radiographic imaging were included. All implants targeted the RV septum per manufacturer recommendation. PICM was defined as ≥10% decline in left ventricular ejection fraction (LVEF) to <50% without alternative cause. RESULTS:PICM developed in 20/81 patients (24.7%), with LVEF declining from 61±8% to 37±9%. Post-implant 3-dimensional radiographic imaging demonstrated inadvertent free wall implantation in 15/20 patients who developed PICM (75%) compared with 8/61 patients who did not (13%; P <0.001). Paced QRS duration was wider in patients with PICM than in those without (186±19 vs 155±13 ms, P <0.001) and discriminated free wall from non-free wall implantation with an area under the receiver operating characteristic curve (AUC) of 0.85; a QRS duration of 172 ms provided optimal discrimination. Baseline LVEF, baseline QRS duration, and comorbidity burden did not differ between groups. CONCLUSIONS:Inadvertent free wall LP implantation is strongly associated with the subsequent development of PICM. Paced QRS duration is a readily available surrogate for implant location, and targeting a paced QRS duration below approximately 172 ms at the time of implant may serve as a practical, non-invasive check on appropriate septal placement.

BACKGROUND:The value of additional lesion sets beyond pulmonary vein isolation (PVI) for atrial fibrillation (AF) ablation is unclear. However, existing studies evaluated the utility of substrate modification with conventional energy sources. There is limited data evaluating PVI with posterior wall isolation (PWI) using pulsed field ablation (PFA). METHODS:We studied consecutive cases of patients with paroxysmal AF undergoing first-time ablation with PFA between May 6, 2024 and March 10, 2025. Procedural data collected included the number of PFA applications administered, total procedure time, and major periprocedural complications. Clinical data collected included atrial tachyarrhythmia (ATA) recurrence, stroke, and major bleeding at 1-year follow-up. Outcomes were compared in patients undergoing PVI alone versus PVI plus PWI. RESULTS:A total of 249 patients were included in this study (104 PVI alone, 145 PVI plus PWI). There was no difference in ATA recurrence by Kaplan-Meier survival analysis comparing PVI alone versus PVI plus PWI (log rank test p = 0.89). When comparing PVI alone versus PVI plus PWI, there was no difference in ATA recurrence at 1 year (16% vs. 16%; p = 0.92), AF burden on continuous monitoring (2% vs. 2%; p = 0.81), total procedure time (114 vs. 107 min; p = 0.14), or major periprocedural complications (0 vs. 3; p = 0.14). CONCLUSION/CONCLUSIONS:PFA for paroxysmal AF with PVI alone or PVI plus PWI produces similar sinus rhythm maintenance without affecting procedure times or complication rates.

BACKGROUND:The optimal number of pulsed field ablation (PFA) applications during atrial fibrillation (AF) ablation is unclear. We hypothesized that the number of PFA applications would predict atrial tachyarrhythmia (ATA) recurrence rates. OBJECTIVE:To determine whether higher numbers of PFA applications would decrease ATA recurrence rates. METHODS:We studied cases of patients with AF undergoing first-time ablation with PFA between 5/6/24 and 10/7/24. All patients underwent pulmonary vein and posterior wall isolation. The primary outcome was ATA recurrence. Additional outcomes included stroke, post-procedural acute kidney injury (AKI), total procedure time, and major periprocedural complications. Univariable and multivariable analyses were performed to determine if the number of PFA applications predicted ATA recurrence. RESULTS:In a cohort consisting of 177 patients, univariable and multivariable analysis showed that the number of PFA applications split at the smallest quartile (< 57 applications) versus the largest three quartiles (≥ 57 applications) was the strongest predictor of ATA recurrence (p = 0.03). ATA recurrence at 1 year (29% vs. 8%; p < 0.01) and AF burden on continuous monitor (4% vs. 0%; p < 0.01) was higher with the standard (< 57 applications) vs higher (≥ 57 applications) PFA dose groups. When comparing the standard versus higher PFA dose groups, there was no difference in total procedure time (106 vs. 107 min; p = 0.77), major periprocedural complications (0% vs. 2%; p = 0.33), or post-procedural AKI (2% vs. 2%; p = 0.69). CONCLUSION/CONCLUSIONS:Increasing number of PFA applications is associated with reduced ATA recurrence. A higher number of PFA applications may decrease ATA recurrence without affecting procedure times or complication rate.

BACKGROUND:Raghib syndrome is a congenital anomaly that is caused by a persistent left superior vena cava draining into the left atrium, unroofed coronary sinus, and atrial septal defect. It can lead to cyanosis, cryptogenic strokes, pulmonary hypertension, and arrythmias. CASE SUMMARY/METHODS:A 60-year-old woman presented with palpitations due to atrial flutter. Cardiac imaging, including computed tomography, transesophageal echocardiography, and magnetic resonance imaging, confirmed bilateral superior vena cavae, with the left superior vena cava draining into the left atrium and minimal right-to-left shunting (3%). She was managed with anticoagulation and underwent regular follow-up without complications. DISCUSSION/CONCLUSIONS:Diagnosis of Raghib syndrome relies on multimodality imaging. In cases with minimal symptoms and left-to-right shunting, conservative management with biannual follow-up may be sufficient. TAKE-HOME MESSAGES/CONCLUSIONS:Multimodality imaging is crucial in confirming anatomy and characterizing flow dynamics in cyanotic congenital heart disease. In patients with Raghib syndrome without cyanosis, conservative management with anticoagulation may be a safe alternative to surgical intervention.

Randomized trials of ethanol infusion into the vein of Marshall (EIVOM) have shown efficacy in preventing atrial fibrillation (AF) recurrence in patients presenting for de novo ablation. The utility of EIVOM in AF patients who present for redo ablation is unclear. This meta-analysis was reported according to the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. Medline, Scopus, and Cochrane Central Register of Controlled Trials were systematically searched to identify relevant studies. Risk of bias was assessed using the Modified Newcastle-Ottawa scale. Eligible studies reported outcomes in AF patients with previous ablation who underwent redo catheter ablation (CA) alone vs. combined redo CA and EIVOM. Five observational studies comprising 568 patients were included. When comparing combined redo CA and EIVOM vs. redo CA alone, pooled results showed no difference in freedom from arrhythmia (FFA) in all patients (risk ratio [RR] 1.13; 95% confidence interval [CI] 0.96-1.33), FFA in persistent AF patients only (RR 1.08; 95% CI 0.90-1.29), total procedure time (mean difference -0.59; 95% CI -41.04-39.85), or major periprocedural complications (RR 0.81; 95% CI 0.06-11.64). Patients with AF recurrence after ablation represent a difficult-to-treat population. Salvage therapy with combined CA and EIVOM did not improve arrhythmic outcomes compared to CA alone in AF patients who presented for redo ablation.

UNLABELLED:Oral anticoagulation (OAC) remains the primary means of stroke prevention in patients with atrial fibrillation (AF). However, there are patients at greater risk of bleeding or who have experienced major bleeding, whereby long term OAC is relatively contraindicated. Additionally, up to 55% of eligible AF patients do not utilize OAC. Thus, transcatheter left atrial appendage occlusion devices (LAAOD) present an attractive alternative to mitigate stroke risk. Randomized trials have demonstrated the noninferiority of LAAOD to OAC in reducing stroke risk. However, treatment with LAAODs presents its own risks, including the risk of device-related thrombus (DRT). In this report, we describe an unusual case of a patient with a small DRT initially identified on transesophageal echocardiography (TEE) 6 weeks after implantation of a Watchman FLX (Boston Scientific, Marlborough, MA, USA) LAAOD that was appropriately treated and resolved on TEE 6 months after implantation. However, a massive late DRT recurred 2 years after implantation. This case highlights the importance of continued device monitoring for unfavorable evolution of DRT beyond the currently recommended 45-day to 1-year monitoring period, and especially after suspected thrombus resolution. Furthermore, it underlines the importance of developing newer generation LAAOD that reduces DRT risk. LEARNING OBJECTIVE/UNASSIGNED:Left atrial appendage occlusion devices can mitigate stroke risk in atrial fibrillation patients with contraindications to oral anticoagulation. However, these devices present with their own risks, including the risk of device-related thrombus (DRT). This case highlights the importance of continued device monitoring for unfavorable evolution of DRT beyond the recommended 45-day to 1-year monitoring period.

INTRODUCTION/BACKGROUND:Sphere-9 is a lattice tip ablation catheter (Medtronic, USA) capable of delivering both pulsed field and radiofrequency ablation. It is approved for the treatment of atrial fibrillation. Adverse events related to this device have been reported to national databases. A systematic assessment of these reports is needed to understand the nature of device-related complications. METHODS:We queried the FDA Manufacturer and User Facility Device Experience (MAUDE) database between October 24, 2024 and October 24, 2025 to identify reports related to the Sphere-9 catheter. A total of 222 reports were included in the final analysis. RESULTS:Of 222 reports, 148 (67%) resulted in clinical events. Of these, 107 were suspected to be related to the Sphere-9, including: VT/VF during/following energy delivery (n = 30), Stroke/TIA (n = 25), sinus node dysfunction/AV block (n = 23), pericardial effusion (n = 7), coronary spasm (n = 9), and phrenic nerve injury (n = 2). Catheter/defibrillator (ICD) related interactions were suspected in 10 of the VT/VF reports. There were 65 catheter related reports that did not appear to be associated with adverse clinical events, which included tissue/char formation on the catheter tip (n = 24), steam pop (n = 25), and mechanical entrapment (n = 7). CONCLUSION/CONCLUSIONS:This early analysis of adverse events reported for the Sphere-9 catheter highlights complications including arrhythmias, such as VT/VF and AV block, and the risks associated with ICD-catheter related interactions.

BACKGROUND:Pulmonary vein isolation (PVI) and posterior wall isolation (PWI) are frequently used in the treatment of persistent atrial fibrillation (AF). Minimal data support adjunct PWI, possibly due to lack of durability via epicardial reconnections. OBJECTIVE:To determine the impact of very high output PW pace-capture testing in patients with persistent AF on AF/AT recurrence. METHODS:We performed a retrospective study of consecutive patients who underwent radiofrequency ablation for persistent AF and received PVI and PWI, as well as a cavotricuspid isthmus line (CTI). After the creation of three linear PW lesions (roof, carina-to-carina, and inferior PV levels), pace-capture testing was performed on the PW. The first cohort confirmed PWI using 10 mA at 2 ms (10 × 2) to pace capture. Sequentially, the second cohort utilized 20 mA at 10 ms (20 × 10). If the PW was captured, additional lesions were performed. Patients were excluded if additional lesion sets beyond PVI, PWI, and CTI were performed. RESULTS:A total of 232 patients were included. Of these, 129 (56%) patients were in the 20 × 10 group, and 103 (44%) patients were in the 10 × 2 group. The two groups did not differ in age, sex, proportion of comorbidities, presenting rhythm, left ventricular ejection fraction, or left atrial size. Despite the increase in procedure time and lesion number, in the time-to-event analysis, patients in the 20 × 10 group experienced recurrent AF/AT more frequently than those in the 10 × 2 group (log rank p = 0.01). CONCLUSION/CONCLUSIONS:Testing PWI in persistent AF with pace capture at 20 mA at 10 ms did not improve freedom from arrhythmia and may paradoxically be associated with harm. Our findings question whether PWI, regardless of durability, is effective in treating persistent AF.

INTRODUCTION/BACKGROUND:A lower frequency early electrogram (EGM) or broad area of early activation during premature ventricular contraction (PVC) mapping may be associated with a PVC origin in an opposing chamber or deep within the mapped surface. The utility of quantifying EGM frequency at early activation sites and isochronal activated surface area (IASA) is unclear. Our study aimed to investigate the utility of EGM frequency analysis and IASA mapping to complement activation mapping during PVC ablation. METHODS:High density PVC activation and IASA maps were created using a multi-electrode mapping catheter in 25 patients undergoing PVC ablation. EGMs in early activation regions were retrospectively studied. IASAs in each mapped chamber were analyzed. RESULTS:within 10 ms was unsuccessful. CONCLUSION/CONCLUSIONS:Higher EGM frequency and smaller IASA were associated with successful ablation of PVCs. Ablation at sites with EGM frequency > 325 Hz was successful in all patients. The utility of identifying higher frequency EGMs at early activation sites requires further study.

BACKGROUND:Identifying nearfield and farfield signals is critical to mapping and ablating cardiac arrhythmias. This assessment is qualitative, depending on the "sharpness" of pulmonary vein (PV) electrograms. Electrogram peak frequency (PF) analysis is hypothesized to be a quantitative measure of signal proximity. OBJECTIVE:To confirm if PF defines nearfield versus farfield electrical signals and if it can be used during ablation to establish pulmonary vein isolation (PVI). METHODS:We created a cohort of 30 patients with AF undergoing PVI. Left atrial and PV maps of PF were generated before and after PVI. In the first 10 patients with paroxysmal AF (cohort 1), a cutoff value was selected to predict nearfield versus farfield signals. This cutoff was validated in a cohort of 10 patients with paroxysmal AF (cohort 2) and a cohort of 10 patients with persistent AF (cohort 3). RESULTS:PF was lower in farfield electrograms than nearfield electrograms. A PF cutoff of 300 Hz had a sensitivity of 93.2% (95% CI 81.3% - 98.6%) in cohort 1, 90.0% (95% CI 76.3 - 97.2) in cohort 2, and 98.6% (95% CI 90.1 - 99.7%) in cohort 3 for differentiating farfield from nearfield electrograms. The specificity was 100.0% (95% CI 98.2% - 100.0%) and the AUC was 0.99 (95% CI 0.97 - 1.00) in all patients. CONCLUSIONS:We confirmed the hypothesis that PF distinguishes nearfield from farfield electrograms. PF analysis improves the recognition of PV isolation. Mapping and ablation strategies utilizing PF should be pursued to improve ablation outcomes.