Killu, Ammar M.

Abstract Background Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM). There is limited data regarding the outcomes of AF catheter ablation in HCM patients. In this study, we aimed to synthesize all available evidence on the effectiveness of ablation of AF in patients with HCM compared to those without HCM. Methods and results We systematically reviewed bibliographic databases to identify studies published through February 2023. We included cohort studies with available quantitative information on rates of recurrent atrial arrhythmias, anti-arrhythmic drug (AAD) therapy, and repeat ablation procedures after initial AF ablation in patients with vs without HCM. Estimates were combined using random-effects meta-analysis models and reported as risk ratios (RR) and 95% confidence intervals (CI). Eight studies were included in quantitative synthesis (262 HCM and 642 non-HCM patients). During median follow-up 13–54 months across studies, AF recurrence rates ranged from 13.3% to 92.9% in HCM and 7.6% to 58.8% in non-HCM patients. The pooled RR for recurrent atrial arrhythmia after the first AF ablation in HCM patients compared to non-HCM controls was 1.498 (95% CI = 1.305–1.720; P < 0.001). During follow-up, HCM patients more often required AAD therapy (RR = 2.844; 95% CI = 1.713–4.856; P < 0.001) and repeat AF ablation (RR = 1.544; 95% CI = 1.070–2.228; P = 0.02). The pooled RR for recurrent atrial arrhythmias after the last AF ablation was higher in patients with HCM than those without HCM (RR = 1.607; 95% CI = 1.235–2.090; P < 0.001). Conclusions Compared to non-HCM patients, those with HCM had higher rates of recurrent atrial arrhythmias, AAD use, and need for repeat AF ablation after initial ablation of AF.

AbstractIntroductionData regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation in patients with aortic valve (AV) intervention (AVI) is limited. Catheter ablation (CA) can be challenging given perivalvular substrate in the setting of prosthetic valves. We sought to investigate the characteristics, safety, and outcomes of CA in patients with prior AVI and ventricular arrhythmias (VA).MethodsWe identified consecutive patients with prior AVI (replacement or repair) who underwent CA for VT or PVC between 2013 and 2018. We investigated the mechanism of arrhythmia, ablation approach, perioperative complications, and outcomes.ResultsWe included 34 patients (88% men, mean age 64 ± 10.4 years, left ventricular (LV) ejection fraction 35.2 ± 15.0%) with prior AVI who underwent CA (22 VT; 12 PVC). LV access was obtained through trans‐septal approach in all patients except one patient who had percutaneous transapical access. One patient had combined retrograde aortic and trans‐septal approach. Scar‐related reentry was the dominant mechanism of induced VTs. Two patients had bundle branch reentry VTs. In the VT group, substrate mapping demonstrated heterogeneous scar that involved the peri‐AV area in 95%. Despite that, the site of successful ablation included the periaortic region only in 6 (27%) patients. In the PVC group, signal abnormalities consistent with scar in the periaortic area were noted in 4 (33%) patients. In 8 (67%) patients, the successful site of ablation was unrelated to the periaortic area. No procedure‐related complications occurred. The survival and recurrence‐free survival rate at 1 year tended to be lower in VT group than in PVC group (p = .06 and p = .05, respectively) with a 1‐year recurrence‐free survival rate of 52.8% and 91.7%, respectively. No arrhythmia‐related death was documented on long‐term follow‐up.ConclusionCA of VAs can be performed safely and effectively in patients with prior AVI.

Background Left (LAAA) and right atrial appendage aneurysms (RAAA) are rare entities, and their natural history, management, and long-term outcomes are not well studied. Methods This retrospective review includes all patients from 2000 to 2021 with atrial appendage aneurysms at our institution identified using an electronic search tool. LAAA and RAAA were confirmed using multimodality imaging and intraoperative findings. Results We identified 13 (87%) patients with LAAA and 2 (13%) with RAAA. At diagnosis, 11 (73%) were female, mean age was 51.4 ± 18.8 years, and ejection fraction 56.5 ± 13.1%. Three (20%) patients had congenital heart disease including 2 (13%) with atrioventricular septal defects and 1 (7%) with congenitally corrected transposition. LAAA/RAAA was diagnosed due to new-onset atrial fibrillation (AF) in 6 (40%) patients and embolic stroke in 2 (13%). Ten patients had preexisting AF diagnosed 2.9 ± 1.4 years earlier at a mean age of 50.2 ± 15.5 years. Thrombus within the aneurysm was identified in 2 (15%) LAAA patients. All patients were on anticoagulation and follow-up of the cohort from diagnosis was 7.1 ± 6.2 years. Eleven (73%) patients were surgically managed with 7 (64%) lesions excised, 1 (9%) stapled, and 3 (27%) ligated. Postoperative complications occurred in 2 (18%) patients with 1 (7%) developing tricuspid regurgitation and another with pericardial effusion and tamponade. Conclusions Atrial appendage aneurysm is a rare disease and nearly half of patients present with AF. Surgical treatment with concomitant AF ablation is a reasonable and safe management option.

Background: Left ventricular outflow tract obstruction may occur following transcatheter mitral valve replacement in the setting of mitral annular calcification. Methods: We present a case series whereby preemptive septal radiofrequency ablation (RADIO-TMVR) was used to augment the left ventricular outflow tract for transcatheter mitral valve replacement in 4 patients at risk for left ventricular outflow tract obstruction despite alcohol septal ablation. Results: All patients were female, average age of 74.9 (68.8–80.4) years. Baseline ejection fraction was 71% (63%–75%). Mean mitral valve area was 1.28 (range, 1.0–1.59) cm 2 . Mean mitral valve gradient at rest was 9.5 (range, 7–11) mm Hg. New York Heart Association symptoms were III to IV at baseline. Patients underwent preemptive septal radiofrequency ablation to prevent left ventricular outflow tract obstruction with transcatheter mitral valve replacement a range between 69 and 154 days after alcohol septal ablation. Procedural time was 384 (337–424) minutes with a fluoroscopic time of 31 (14–71) minutes. Radiofrequency ablation time was 132 (100–175) minutes. As anticipated, 3 patients developed complete heart block and underwent pacemaker implantation, whereas 1 had a preexisting pacemaker. One patient developed groin hematoma and heart failure exacerbation. There were no peri-procedural deaths. Preemptive septal radiofrequency ablation to prevent left ventricular outflow tract obstruction with transcatheter mitral valve replacement resulted in septal end-diastolic wall thickness reduction compared with baseline (28.6%, 30.4%, 30.3%, and 11.1%) and following alcohol septal ablation (23.1%, 12%, 8.5%). Valve replacement in the setting of mitral annular calcification was performed in all patients 89 (range, 38–45) days after preemptive septal radiofrequency ablation to prevent left ventricular outflow tract obstruction with transcatheter mitral valve replacement. Two patients had concomitant laceration of the anterior mitral leaflet to further augment the neo-left ventricular outflow tract. Postprocedure, New York Heart Association symptoms improved to class I (3 patients) and class II (1 patient). Conclusions: In at-risk individuals, preemptive septal radiofrequency ablation may be an effective strategy at preventing left ventricular outflow tract obstruction with transcatheter mitral valve replacement.

Abstract Background The use of irreversible electroporation (IRE) for cardiac ablation in the management of cardiac arrhythmias, known as Pulsed Field Ablation (PFA), has gained the attention of many researchers, physicians and companies. Despite the demonstrated efficacy and safety profiles of the technique, there are still many open questions. One of them deals with the effective electric field thresholds necessary for cardiac tissue ablation. Contrary to radiofrequency (RF) ablation, where the thermotemporal thresholds for tissue damage are well established, the electric field thresholds for effective IRE are uncertain and depend on the tissue type and the waveform characteristics of the delivered electric field. Purpose The use of numerical models to understand the electric field distribution and the corresponding lesion for a specific electrode geometry are widely used in IRE for cancer treatment. Models can predict ablation volumes when the field thresholds are known or can be used to estimate the field thresholds when the lesion geometry is established post-treatment. The goal of the present study was to build a subject-specific realistic 3D numerical model to assess the ability of modeling to predict PFA lesions. Methods PFA experiments were performed in male mongrel dogs following a protocol approved by the Mayo Clinic Institutional Animal Care and Use Committee. Briefly, animals were sedated and intubated, and two non-irrigated deflectable catheters with an 8-mm tip were positioned on both sides of the interventricular septum under fluoroscopy guidance. Submicrosecond pulses were delivered in a bipolar fashion across both catheters. Sequences of pulses of 300 ns duration (or other durations in that range) were repetitively applied with voltage levels in the kV range. 30 days after the procedure, MRI with late gadolinium enhancement (LGE) were acquired to assess the presence of ablation lesions in the treated tissue. Ventricular areas were segmented from MRI images and 3D volumes were created. The generated 3D geometries were imported into software COMSOL Multiphysics. Realistic 3D geometries of the catheters were placed in the same positions than during the experiments, fluoroscopy videos recorded during the procedures were used as a guidance. The computed electric field intensity distributions were compared to the LGE areas to extract the range of electric field thresholds where the predicted lesion size was compatible with the real size of the LGE areas for each application site and pulsing protocol. Results and conclusions Our results show how the numerical model is able to reproduce the shape of the LGE fibrotic lesion areas observed 30 days after the procedure. Additionally, the model clearly confirms the dose-dependent lesion sizes observed experimentally. This study supports that numerical modeling is a valuable tool for understanding PFA treatments and that it could be used as patient-specific treatment planning tool. Funding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie

Background: Previous animal studies have shown no significant vascular injury from pulsed electrical field (PEF) ablation. We sought to assess the effect of PEF on swine coronary arteries. Methods: We performed intracoronary and epicardial (near the coronary artery) PEF ablations in swine pretreated with dual antiplatelet and antiarrhythmic therapy. Intracoronary PEF was delivered using MapiT catheters (Biotronik, Berlin), whereas epicardial PEF was delivered using EPT catheters (Boston Scientific, MA). PEF pulse duration was microseconds (Nanoknife 3.0, Angio Dynamics, NY) or nanoseconds (CellFX, Pulse Biosciences, CA). Results: We performed 39 intracoronary ablations in 10 swine and 20 epicardial-pericoronary ablations in 4 separate swine. Intracoronary PEF was delivered at higher energy compared with epicardial PEF (46 [interquartile range, IQR 20–85] J versus 10 [IQR 10–11] J, P < 0.01). Reversible coronary spasm occurred in 49% intracoronary ablations and 45% epicardial ablations ( P =0.80). At the end study, fixed coronary stenosis was demonstrated in 44% intracoronary ablations (80% for microsecond PEF and 18% for nanosecond PEF) and 0% epicardial ablations. Visible hemorrhagic and/or fibrotic myocardial lesions were observed at necropsy with similar frequency between intracoronary and epicardial PEF (45% versus 50%, P =0.70). Nanosecond PEF (49 ablations in 11 swine), when compared with microsecond PEF (10 intracoronary ablations in 3 swine), resulted in lower energy delivery (21 [IQR 10–46] J versus 129 [IQR 24–143] J, P =0.03) and less incidence of fixed coronary stenosis (18% versus 80%, P =0.04). Conclusions: In the swine model, intracoronary PEF resulted both in significant coronary spasm and fixed coronary stenosis. Epicardial PEF, delivered at lower energy, resulted in reversible spasm but no fixed coronary stenosis.

Background: Mitral annular disjunction (MAD) has recently been recognized as an arrhythmogenic entity. Data on the electrophysiological substrate as well as the outcomes of catheter ablation of ventricular arrhythmias in patients with MAD is limited. Methods: Forty patients with MAD (mean age 47±15 years; 70% female) underwent catheter ablation for ventricular arrhythmias. Detailed clinical, electrocardiographic, cardiac imaging, and procedural data were collected. Clinical outcomes were compared between patients who had substrate modification in the MAD area and those who did not. Results: Twenty-three (57.5%) patients had ablation for premature ventricular contractions, 10 (25%) patients for sustained ventricular tachycardia, and 7 (17.5%) patients for premature ventricular contraction-triggered ventricular fibrillation. Mean end-systolic MAD length was 10.58±3.49 mm on transthoracic echocardiography. Seventeen (42.5%) patients had preprocedural cardiac magnetic resonance imaging, and 5 (29%) patients had late gadolinium enhancement. Among the 18 (45%) patients who had abnormal local electrograms (low voltage, long-duration, fractionated, isolated mid-diastolic potentials) during electroanatomical mapping, 10 (25%) patients had abnormal electrograms in the anterolateral mitral annulus and/or MAD area. Substrate modification was performed in 10 (25%) patients. Catheter ablation was acutely successful in 36 (90%) patients (elimination of premature ventricular contraction or noninducibility of ventricular tachycardia). After a median follow-up duration of 54.08 (interquartile range, 10.67–89.79) months, premature ventricular contraction burden decreased from a median of 9.75% (interquartile range, 3.25–14) before the ablation to a median of 4% (interquartile range, 1–7.75) after the ablation ( P =0.03 [95% CI, 0.055–6.5]). Eight (20.5%) patients had repeat ablation for ventricular arrhythmias. Substrate modification of the MAD was associated with a trend toward lower rates of repeat ablation (0% versus 26.7%; P =0.16). Conclusions: Patients with MAD have a complex arrhythmogenic substrate, and catheter ablation is effective in reducing recurrence of ventricular arrhythmias. Substrate mapping and ablation may be considered in these patients.

Background: Ablation of ventricular tachycardia (VT) is limited by the inability to create penetrating lesions to reach intramyocardial origins. Intramural needle ablation using in-catheter, heated saline-enhanced radio frequency (SERF) energy uses convective heating to increase heat transfer and produce deeper, controllable lesions at intramural targets. This first-in-human trial was designed to evaluate the safety and efficacy of SERF needle ablation in patients with refractory VT. Methods: Thirty-two subjects from 6 centers underwent needle electrode ablation. Each had recurrent drug-refractory monomorphic VT after implantable cardioverter defibrillator implantation and prior standard ablation. During the SERF study procedure, one or more VTs were induced and mapped. The SERF needle catheter was used to create intramural lesions at targeted VT site(s). Acute procedural success was defined as noninducibility of the clinical VT after the procedure. Patients underwent follow-up at 30 days, and 3 and 6 months, with implantable cardioverter defibrillator interrogation at follow-up to determine VT recurrence. Results: These refractory VT patients (91% male, 66±10 years, ejection fraction 35±11%; 56% ischemic, and 44% nonischemic) had a median of 45 device therapies (shock/antitachycardia pacing) for VT in the 3 to 6 months pre-SERF ablation. The study catheter was used to deliver an average of 10±5 lesions per case, with an average of 430±295 seconds of radiofrequency time, 122±65 minute of catheter use time, and a procedural duration of 4.3±1.3 hours. Acute procedural success was 97% for eliminating the clinical VT. At average follow-up of 5 months (n=32), device therapies were reduced by 89%. Complications included 2 periprocedural deaths: an embolic mesenteric infarct and cardiogenic shock, 2 mild strokes, and a pericardial effusion treated with pericardiocentesis (n=1). Conclusions: Intramural heated saline needle ablation showed complete acute and satisfactory mid-term control of difficult VTs failing 1 to 5 prior ablations and drug therapy. Further study is warranted to define safety and longer-term efficacy. Registration: URL: https://www.clinicaltrials.gov ; Unique Identifier: NCT03628534 and NCT02994446.

Abstract Background: Atrial fibrillation (AF) is relatively less frequent in younger patients (age<50). Recently, studies have suggested that early restoration of sinus rhythm may lead to improved outcomes compared with rate control. Methods: We included all hospitalized patients between 18 and 50 years with a diagnosis of AF from the Nationwide Readmission Database 2016-2017 from the Healthcare Cost and Utilization Project. Demographic and comorbidity data were collected and analyzed. Outcomes assessed included one-year AF readmission rates, all-cause readmission, ischemic stroke, and all-cause mortality. Subgroup analyses were performed for all demographic and comorbidity variables.Results: Overall, 52,598 patients (medium age 44, interquartile range 38-48, female 25.7%) were included in the study, including 2,146 (4.0%) who underwent catheter ablation for AF. Patients who underwent catheter ablation had a significantly lower rate of readmission for AF or any cause at one year (adjusted hazard ratios (HR) of 0.52 [95% confidence interval (CI): 0.43-0.63] and HR of 0.81 [95% CI: 0.72 - 0.89], respectively). There was no difference in 1-year readmission for stroke or all-cause mortality between the two groups. Subgroup analyses showed a consistent reduction in the risk of AF readmission among major demographic and comorbidity subgroups.Conclusion: Catheter ablation in young patients with AF was associated with a reduction in 1-year AF related and all-cause readmissions. These data merit further prospective investigation for validation.