BACKGROUND:Catheter ablation (CA) is a widely used therapy for atrial fibrillation (AF), but limited research compares the effectiveness of CA with antiarrhythmic drugs (AADs) in an elderly population. OBJECTIVE:This study aimed to compare AF recurrence and other clinical outcomes for CA with AADs in an elderly population with drug-refractory AF. METHODS:A large nationally representative sample of elderly patients (aged ≥65 years) was studied using the Optum Clinformatics database from 2016 to 2022. The primary outcome was atrial tachyarrhythmia recurrence. Secondary outcomes included direct current cardioversions, heart failure (HF) hospitalizations, myocardial infarctions, ischemic strokes, and death. Propensity score matching was used to balance cohorts. RESULTS:13,311 patients were identified, with 7230 in the AAD cohort and 6081 in the CA cohort. Patients who underwent CA were 24% less likely to experience recurrence compared with those treated with AADs (hazard ratio [HR] 0.76; 95% confidence interval [CI] 0.65-0.89). The risk of direct current cardioversion (HR 0.74; 95% CI 0.60-0.91), HF hospitalization (HR 0.63; 95% CI 0.45-0.90), and ischemic stroke (HR 0.45; 95% CI 0.28-0.72) was significantly reduced, without differences in death or myocardial infarction. The rate of complications was 5.9% in the CA cohort, whereas adverse events were frequent in the AAD cohort (45.4%). CONCLUSION:CA treatment was associated with a lower risk of atrial tachyarrhythmia, cardioversion, HF hospitalization, and ischemic stroke than AADs. AADs were poorly tolerated in this cohort, and complication rates from CA were similar to those of younger groups. Favorable safety and efficacy support consideration of CA in elderly patients.

BACKGROUND:The left atrial appendage (LAA) is a trigger for atrial fibrillation (AF) in nearly one-third of patients with persistent AF undergoing repeat ablation, and LAA isolation (LAAI) has been shown to improve arrhythmia outcomes. Previous studies of LAAI using an ostial approach without vein of Marshall ethanol ablation (VOM) resulted in variable rates of acute and durable LAAI and an elevated risk of stroke. OBJECTIVE:This study aimed to assess the feasibility and effect of LAAI using an anterior mitral isthmus line (AML) and posterior mitral isthmus line (PML), with adjunctive VOM, in patients with persistent AF undergoing repeat ablation. METHODS:We prospectively identified 23 patients undergoing repeat ablation for persistent AF in whom LAAI was intentionally performed via AML and PML ± VOM from 2023 to 2024. Patients were systematically remapped at the time of LAA occlusion to assess LAAI durability. Arrhythmia-free survival was assessed using Kaplan-Meier analysis. RESULTS:The mean age was 72 years, 74% of patients were male, and 87% were white. VOM was successfully performed in 74% of cases, and LAAI was achieved acutely in all. The rate of durable LAAI was 61% and the arrhythmia recurrence rate was 61% at 1 year, with atrial tachycardia occurring more frequently than AF. There was no evidence of acute thrombus, and no strokes or transient ischemic attacks occurred. CONCLUSION:LAAI using a linear approach of AML and PML with VOM is feasible and reproducible and results in a low rate of arrhythmia recurrences, most of which are self-limited.

BACKGROUND:The boundaries of critical isthmuses for re-entrant ventricular tachycardia (VT) are formed by wavefront discontinuities (fixed lines of block, slow propagation, and rotational propagation) seen during baseline rhythm. It is unknown whether wavefront discontinuities can be automatically identified and targeted for ablation using electroanatomic mapping systems. OBJECTIVES:The purpose of this study was to assess the electrophysiologic characteristics of automatically projected wavefront discontinuity lines (WADLs) and outcomes of an ablation strategy targeting WADLs in a mixed cohort of VT patients. METHODS:Late activation substrate maps were analyzed from 1 or more baseline rhythm wavefronts. WADLs were identified using the Carto Extended Early Meets Late module. Number, total length, and distance to critical VT sites were measured. VT recurrence and VT-free survival were followed. RESULTS:In total, 49 patients underwent 52 ablations with 71 unique substrate maps analyzed (18.8% epicardial; 62.0% right ventricular paced, 28.2% sinus rhythm, 9.9% left ventricular paced). A total of 28 VT critical sites were identified in 24 patients. WADLs were present in 49 of 71 (69.0%) maps. WADLs were present regardless of cardiomyopathy etiology, mapping wavefront, or surface. At a WADL threshold of 30%, 73.9% of critical VT sites were in close proximity (≤15 mm) to a WADL. VT-free survival was 62% at 1 year, with a competing risk model estimating a 1-year risk of VT recurrence of 23%. CONCLUSIONS:WADLs can be automatically projected in a majority of patients in a mixed cohort of cardiomyopathy etiology, mapped wavefronts, and myocardial surfaces mapped. Targeting WADLs results in low rate of VT recurrence at 1 year.

With the expanding use of cardiac implantable electronic device (CIED) therapy, intravascular device infections are becoming more common. In the case of transvenous implantable cardioverter-defibrillator (ICD) infections requiring extraction for bacterial clearance, there remains no standard method to deliver temporary ICD therapy following device removal. We present a case of persistent bacteremia complicated by monomorphic ventricular tachycardia (VT) electrical storm where biventricular ICD system extraction was performed and a temporary transvenous dual-coil lead with an externalized ICD generator was used to treat VT episodes prior to the re-implantation of a new permanent system. This case demonstrates the utility of a temporary externalized transvenous ICD system in the successful detection and pace-termination of VT, thereby reducing episodes of painful and potentially harmful external defibrillator shocks during the treatment of CIED infection.

Posterior wall isolation (PWI) can be a useful adjunct to pulmonary vein isolation (PVI) for the management of persistent atrial fibrillation (AF). Successful isolation of the posterior wall is challenging, with first-pass isolation rates under 40%. Difficulties in achieving block may be due to inability to create transmural lesions due to complex posterior wall architecture from septopulmonary (SPB) and septoatrial (SAB) bundle insertion. Activation mapping using omnipolar technology (OT) may allow identification of areas of anisotropic conduction that represent atrial fiber and bundle insertion points to target for additional ablation.

Pilot clinical studies suggest that very high power–very short duration (vHPvSD, 90 W/4 s, 360 J energy) is a feasible and safe technique for ablation of atrial fibrillation (AF), compared with standard applications using moderate power–moderate duration (30 W/30 s, 900 J energy). However, it is unclear whether alternate power and duration settings for the delivery of the same total energy would result in similar lesion formation. This study compares temperature dynamics and lesion size at different power-duration settings for the delivery of equivalent total energy (360 J). An in silico model of radiofrequency (RF) ablation was created using the Arrhenius function to estimate lesion size under different power-duration settings with energy balanced at 360 J: 30 W/12 s (MPSD), 50 W/7.2 s (HPSD), and 90 W/4 s (vHPvSD). Three catheter orientations were considered: parallel, 45°, and perpendicular. In homogenous tissue, vHPvSD and HPSD produced similar size lesions independent of catheter orientation, both of which were slightly larger than MPSD (lesion size 0.1 mm deeper, ~ 0.7 mm wider, and ~ 25 mm3 larger volume). When considering heterogeneous tissue, these differences were smaller. Tissue reached higher absolute temperature with vHPvSD and HPSD (5–8 °C higher), which might increase risk of collateral tissue injury or steam pops. Ablation for AF using MPSD or HPSD may be a feasible alternative to vHPvSD ablation given similar size lesions with similar total energy delivery (360 J). Lower absolute tissue temperature and slower heating may reduce risk of collateral tissue injury and steam pops associated with vHPvSD and longer applications using moderate power.

Precise localization of the slow atrioventricular nodal pathway (SP) is crucial to safe and successful ablation of atrioventricular nodal re-entrant tachycardia (AVNRT). However, interpatient anatomic variability can limit ablation efficacy and increase risk for heart block. Activation mapping in sinus rhythm using omnipolar technology (OT) can delineate areas of abrupt change in propagation direction, which may reflect connections between fast and slow pathways of the AVN (Fig 1). As such, OT may offer a novel way to identify the SP and guide ablation of AVNRT.

With the expanding use of CIED therapy, intravascular device infections are becoming more common. In the case of transvenous ICD infections requiring extraction for bacterial clearance, there remains no standard method to deliver temporary ICD therapy following device removal. We present a case of bacteremia and VT storm where CRT-D system extraction is performed to facilitate bacterial clearance. Given active ventricular arrhythmias, a temporary externalized ICD with a transvenous dual-coil lead is used to treat VT episodes prior to reimplantation of a new permanent device. N/A A 78-year-old man presented with dyspnea, hypotension, and VT storm. His past medical history includes a nonischemic cardiomyopathy, chronic HFrEF, recurrent monomorphic VT status post LV summit VT ablation in April, 2022, and initial implant of a right-sided single chamber dual-coil ICD in 2007 followed by CRT-D upgrade in 2016 with improvement in LVEF from 15% to 40%. He was found to have enterococcus faecalis bacteremia. Despite ongoing amiodarone therapy, he had 5 episodes of monomorphic VT in a 6-hour period. Four episodes of VT (CL 380-420msec) were successfully treated with a single round of ATP and one episode of VT (CL 300msec) was successfully terminated with an ICD shock. TEE was without evidence of endocarditis. Despite appropriate antibiotic therapy, blood cultures remained positive suggesting device infection. Laser-assisted device extraction was performed to facilitate bacterial clearance. Concurrently, a temporary transvenous RV dual-coil DF1 lead was placed via the right axillary vein with programming set to bipolar sensing / ATP delivery and shock vector involving only the SVC and RV coils. All therapy vectors incorporating the externalized ICD can were deactivated. The patient had multiple successful ATP therapies utilizing the temporary ICD system (Figure) without the need for external defibrillation. CRT-D reimplant was successful 7 days after extraction. He was discharged with plans to complete a six week course of antibiotics. Management of active ventricular arrhythmias resistant to pharmacologic therapy can be challenging in the setting of transvenous ICD infections requiring device extraction. This case demonstrates the utility of a temporary transvenous ICD in detection and pace-termination of VT, thereby avoiding the need for external defibrillator therapy.

Patients with incessant ventricular tachycardia (VT), sustained VT despite treatment with antiarrhythmic drugs, or shocks from implantable defibrillators are candidates for catheter ablation (CA).1–3 Although ablation can be efficacious, mortality is higher in patients with structural heart disease owing to hemodynamic instability from anesthesia and arrhythmia induction.1,3,4 The PAINESD risk score helps to identify patients at risk of acute hemodynamic decompensation, permitting selection of those likely to benefit from intraprocedural mechanical circulatory support (MCS).

Strategies to prevent right phrenic nerve (PN) injury during catheter ablation can be difficult to employ, ineffective, and risky. A novel PN-sparing technique involving single lung ventilation followed by “intentional pneumothorax” was prospectively evaluated in patients with multidrug refractory periphrenic atrial tachycardia (AT). This hybrid technique, termed PHRENICS (Phrenic Relocation by Endoscopy & Intentional Pneumothorax using Carbon Dioxide & Single Lung Ventilation), resulted in effective PN relocation away from the target site in all cases, allowing successful catheter ablation of AT without procedural complication or arrhythmia recurrence. The PHRENICS hybrid ablation technique can effectively mobilize the PN, avoiding unnecessary invasion of the pericardium, and can expand the safety of catheter ablation for periphrenic AT.

Deep brain stimulation (DBS) is a critical tool for the treatment of advanced, drug-refractory Parkinson's disease using high-frequency stimulation of the subthalamic nucleus and globus pallidus internus. In patients with cooccurring needs for cardiac pacing, there is risk of electrical interference leading to oversensing. To minimize interaction, device manufacturers recommend a minimum distance of 6 inches between generators, which is not feasible with standard pacemaker (PPM) placement in the setting of bilateral DBS.