Haq, Ikram-Ul

BACKGROUND: Ventricular fibrillation (VF) remains a leading cause of sudden cardiac death with an incompletely characterized electrophysiological substrate. Traditional large-animal VF models are limited by hemodynamic collapse and myocardial ischemia. This study establishes a reproducible swine model using dual mechanical circulatory devices to enable high-density electroanatomic mapping under nonischemic conditions. METHODS: Five Yorkshire swine (55–65 kg) underwent sustained VF supported by venoarterial extracorporeal membrane oxygenation (2.5–3.0 L/min) and percutaneous left ventricular unloading (Impella CP, P-2–P-4). High-density electroanatomic mapping using CARTO 7 was performed at baseline and after defibrillation. Bipolar voltage was acquired from 7 predefined ventricular regions (21 measurements per animal per time point; n=210 paired observations). Unipolar voltage mapping and continuous surface ECG monitoring were used to assess acute ischemic injury. Systemic perfusion was maintained at systolic arterial pressure ≥80 mm Hg. Linear mixed-effects modeling was used to analyze voltage changes from pre-VF to post-VF. RESULTS: Sustained VF (10±1 minutes) was reproducibly induced and maintained with consistent hemodynamics (systolic arterial pressure, 90±5 mm Hg; extracorporeal membrane oxygenation flow, 2.5±0.5 L/min). All animals were successfully defibrillated. High-density mapping was feasible in all experiments (1000±300 points per chamber). Bipolar voltage showed no change from pre-VF (5.86±2.56 mV) to post-VF (6.53±2.22 mV; mean difference, 0.67 mV [95% CI, –0.31 to 1.65]; P =0.15). Both left ( P =0.17) and right ventricles ( P =0.08) demonstrated voltage preservation. Regional analysis showed no significant changes (all P >0.05); post-VF voltages remained above viability thresholds (>1.5 mV). Unipolar voltage maps recovered toward baseline, with no ECG injury pattern identified after defibrillation. CONCLUSIONS: Dual mechanical circulatory support with venoarterial extracorporeal membrane oxygenation and Impella CP enables reproducible, high-fidelity electroanatomic mapping and preserves myocardial substrate after sustained VF in a large-animal model. This platform overcomes key technical barriers in VF research, providing a nonischemic foundation for future mechanistic and translational studies.

Abstract Background The extravascular implantable cardioverter defibrillator (EV-ICD) was designed to avoid lead-related complications associated with transvenous systems and deliver features such as anti-tachycardia pacing (ATP) and reduced generator size that provide an advantage over a subcutaneous ICD (S-ICD). As such, the EV-ICD is an attractive alternative for younger patients with genetic heart diseases (GHDs) who are not in need of permanent pacing. Objective To examine the indications, complications, and the clinical outcomes of patients with GHDs who received an EV-ICD. Methods A retrospective review of the electronic record was done for all GHD patients evaluated in genetic heart rhythm and/or cardiomyopathy clinics who had an EV-ICD implanted between 1/2021 and 2/2025. Basic demographic, ICD indications, complications, and therapy data were then extracted for all study patients. Results Overall, 23 patients (35% female; mean age 39 ± 16 years; 61% with a disease-causative genetic variant; mean LVEF 57%) with an underlying GHD (hypertrophic cardiomyopathy in 9, arrhythmogenic cardiomyopathy in 8, idiopathic ventricular fibrillation in 3, dilated cardiomyopathy in 2, and long QT syndrome in 1) had an EV-ICD implanted. For the majority, an EV-ICD was implanted for primary prevention (15/23; 65%) and represented their first ICD system (21/23; 91%). The success rate of the procedure was 96% with only one abandoned procedure because of poor R-wave sensing. Inadvertent intraprocedural lead placement in the pericardial space occurred in 1 patient with previous thoracotomy and surgically placed epicardial lead without sequelae or need for revision. Over a mean follow-up of 8±9 months, the rate of complications was low (1/23; 4%) with one electrode displacement and this patient underwent defibrillation threshold testing (DFT), the device properly detected VF and emitted a successful shock 30 J. Thus far, 2 patients have received appropriate VT/VF-terminating therapies (3 ICD shocks, 0 ATP) with successful conversion to sinus rhythm. One patient died following an electrical storm. One patient had 3 inappropriate ICD shock for sinus tachycardia while exercising followed by 1 successful shock for VF. Conclusion In this early experience, EV-ICDs appear to be safe and effective in younger patients with genetic arrhythmogenic and hypertrophic cardiomyopathies. Future studies are needed to better understand the utility of EV-ICDs in patients with cardiac channelopathies and advantages of EV-ICDs over transvenous and S-ICD systems in patients with an array of sudden death-predisposing GHDs.

Background: Atrial arrhythmia recurrence after surgical ablation remains challenging to predict and integrating novel biomarkers may improve risk stratification. Objective: To evaluate whether combining preoperative transthoracic echocardiography (TTE) with artificial intelligence-enabled ECG (AI-ECG) scores enhances prediction of atrial fibrillation/flutter (AF/AFl) recurrence post surgical ablation. Methods: We retrospectively analyzed 1,696 patients undergoing Surgical AF/AFl Ablation between 2006 and 2025 with preoperative TTE and post-blanking ECGs. Clinical variables, TTE indices, and AI-ECG scores (AF probability, ECG-estimated age, HFpEF, LV dysfunction, and aortic stenosis scores) were assessed. The primary outcome was time to AF/AFl recurrence. Univariate/multivariable Cox models and a Random Survival Forest (RSF) model (80:20, training: testing) were developed to identify predictors. Results: Of 1,696 patients (mean age 67.3±10.2 years; 61.7% male) undergoing surgical AF/AFl ablation, 949 (56%) experienced AF/AFl recurrence during a median follow-up of 3.14 years. Patients with recurrence had larger left atria (mean LA area 30.4 vs 24.5 cm 2 , p < 0.001), more diastolic dysfunction (mitral inflow E-wave velocity 1.015 m/s vs 0.896 m/s , p < 0.001), and adverse AI-ECG biomarkers. In multivariable analysis, independent predictors of recurrence included a higher ECG-AF score (p < 1 x 10 -300 ), an older AI-ECG age (p = 0.0002), LA area (p = 0.046), body mass index (p = 0.036), and elevated diastolic blood pressure (HR 1.008 per mmHg, 95% CI 1.002 – 1.014; p = 0.010). The final Cox model achieved a C-index of ~0.67 and stratified patients into risk quartiles with 3-year freedom-from-arrhythmia rates of ~85% (lowest-risk) vs ~43% (highest-risk). An RSF model yielded a slightly higher test C-index (≈0.69), suggesting modest improvement with non-linear modeling. Conclusions: Preoperative AI-ECG biomarkers (AF probability, age discordance) and TTE markers of atrial remodeling independently predicted AF/AFl recurrence after surgical AF/AFl ablation and integration of these metrics improved risk stratification.

Background: Ventricular tachycardia (VT) is a life-threatening arrhythmia frequently observed in structural heart diseases, including LMNA-related cardiomyopathy, a genetic disorder associated with high risk of sudden cardiac death and progressive systolic dysfunction. While catheter ablation is an established therapeutic option for VT, its efficacy in cardiac laminopathy remains poorly defined. Objectives: To synthesize available evidence on the role and outcomes of VT ablation in patients with cardiac laminopathy. Methods: A systematic review and single-arm meta-analysis was performed in accordance with PRISMA guidelines. PubMed, Embase, and Cochrane databases were searched for studies reporting VT ablation outcomes in LMNA-related cardiomyopathy. An inverse variance random-effects model was applied for meta-analysis of proportions. Results: Seven studies (six cohorts, one abstract) comprising 62 patients (mean age 53.2 ± 9.7 years; 85% male; 88% with implantable cardioverter-defibrillator) were included. An endocardial/endo-epicardial approach was used in 93% of cases. Acute procedural success was achieved in 37% (95% CI: 14–63%; I 2 = 27.4%), and 28% required multiple procedures. Over a median follow-up of 26 (9–35) months, VT recurrence occurred in 91% (95% CI: 76–100%; I 2 = 37.2%). All-cause mortality was 54% (95% CI: 39–70%; I 2 = 28%), predominantly from cardiac causes (51%, 95% CI: 25–76%; I 2 = 53%), and 14% (95% CI: 1–34%; I 2 = 42%) underwent heart transplantation. Conclusions: In LMNA-related cardiomyopathy, catheter ablation is associated with high VT recurrence, limited long-term success, and substantial cardiovascular mortality and transplantation rates, underscoring the importance of ICD implantation and the need for alternative strategies, including variant-specific and molecularly targeted therapies.

ABSTRACT Introduction Lead‐related venous obstruction is a significant complication of chronic indwelling transvenous leads, which poses unique challenges during cardiac device upgrades. Background The anatomical sequelae of venous occlusion are variable and carry important procedural implications. Occlusions can develop in any part of the venous system, but they most often occur in the subclavian and innominate veins, while the superior vena cava is less frequently affected. Methods In this review, we describe approaches to lead‐related venous occlusion providing step‐by‐step procedural guidance. Results Venoplasty, neovascular channel creation are two main techniques for addressing lead‐related venous obstruction. Conclusion Venoplasty in the setting of an indwelling pacemaker or defibrillator leads can be performed safely and effectively. The difficulty of the procedure lies in crossing the obstruction. Familiarity with various tools is needed for a successful outcome.

Background: Transthyretin cardiac amyloidosis (ATTR-CA) carries an elevated risk of developing ventricular arrhythmias (VA) but there remains limited evidence supporting the role of catheter ablation in this population. Purpose: To assess the safety and efficacy of catheter ablation for VA in ATTR-CA. Methods: An electronic database was used to identify all patients suspected of having ATTR-CA who underwent catheter ablation for VA at our institution between January 2010 and December 2023. Patients who did not meet the diagnosis of ATTR-CA and had a negative workup who underwent catheter ablation for ventricular tachycardia (VT) or premature ventricular contractions (PVCs) were used to form a control group matched for age, sex and left ventricular ejection fraction at a ratio of 2:1. Results: 20 controls and 10 cases of ATTR-CA were identified. Examining the two groups at baseline (Table 1), the mean age at index ablation was 67.7±7.0 and 68.6±8.1 years (p=0.359), mean follow-up time was 4.1±3.1 and 4.2±2.6 years (p=0.494), and the proportion of males was 100% and 90% respectively. The ATTR-CA group had a significantly higher proportion of chronic kidney disease (90% vs. 50%, p=0.032) and prior stroke or thrombotic events compared to the control group (50% vs. 10%, p=0.026) with similar CHA 2 DS 2 VASc scores (4.2±1.6 vs. 3.8±1.3, p=0.233). Both groups had comparable left ventricular ejection fraction (41.4%±14% vs. 46.9%±15.2%, p=0.173), VT/PVCs at presentation (40%/60% vs. 25%/75%, p=0.77), use of antiarrhythmics (70% vs. 60%, p=0.592), and high proportion of atrial fibrillation/flutter (70% vs. 90%, p=0.168). Procedural (261.2±101.2 vs. 265.7±125.6 mins, p=0.449) and total energy delivery time (1442.9±1509.1 vs. 1744.6±956.2 secs, p=0.296) was not significantly different in the two groups. Both groups had a significant decrease in PVC burden postablation with a reduction from 26.8% to 3.8% (p=0.024) and from 27.1% to 13.6% (p=0.028) in the ATTR-CA and control group respectively. A downward trend was seen in antitachycardia pacing events for VT postablation in the ATTR-CA (14.7±9.8 vs. 5.3±6.7, p =0.184) and control (193±387.6 vs. 0.67±1.2. p=0.139) groups. No major complications occurred after ablation (Table 2). Mean time to recurrence post-index ablation was similar between both groups (1620.4±483.8 vs. 1498.8±291.4 days, p=0.987, Figure 1). Conclusions: Catheter ablation appears to be safe and effective for VT and PVCs in patients with ATTR-CA.

Abstract Aims The viability of cardiac resynchronization therapy (CRT) in inotrope-dependent heart failure (HF) has been a matter of debate. Methods and results We searched Medline, EMBASE, Scopus, and the Cochrane Library until 31 December 2022. Studies were included if (i) HF patients required inotropic support at CRT implantation; (ii) patients were ≥18 years old; and (iii) they provided a clear definition of ‘inotrope dependence’ or ‘inability to wean’. A meta-analysis was performed in R (Version 3.5.1). Nineteen studies comprising 386 inotrope-dependent HF patients who received CRT (mean age 64.4 years, 76.9% male) were included. A large majority survived until discharge at 91.1% [95% confidence interval (CI): 81.2% to 97.6%], 89.3% were weaned off inotropes (95% CI: 77.6% to 97.0%), and mean discharge time post-CRT was 7.8 days (95% CI: 3.9 to 11.7). After 1 year of follow-up, 69.7% survived (95% CI: 58.4% to 79.8%). During follow-up, the mean number of HF hospitalizations was reduced by 1.87 (95% CI: 1.04 to 2.70, P &lt; 0.00001). Post-CRT mean QRS duration was reduced by 29.0 ms (95% CI: −41.3 to 16.7, P &lt; 0.00001), and mean left ventricular ejection fraction increased by 4.8% (95% CI: 3.1% to 6.6%, P &lt; 0.00001). The mean New York Heart Association (NYHA) class post-CRT was 2.7 (95% CI: 2.5 to 3.0), with a pronounced reduction of individuals in NYHA IV (risk ratio = 0.27, 95% CI: 0.18 to 0.41, P &lt; 0.00001). On univariate analysis, there was a higher prevalence of males (85.7% vs. 40%), a history of left bundle branch block (71.4% vs. 30%), and more pronounced left ventricular end-diastolic dilation (274.3 ± 7.2 vs. 225.9 ± 6.1 mL). Conclusions CRT appears to be a viable option for inotrope-dependent HF, with some of these patients seeming more likely to respond.

Background: Many cardiac implantable devices have the capability of monitoring the volume status in patients with heart failure by tracking the intra-thoracic impedance changes over time measured by OptiVol fluid index. Objective: The aim of this study is to evaluate the association between the intra-thoracic impedance measured by OptiVol fluid index and the onset of tachyarrhythmias. Methods: We searched Medline and EMBASE databases through January 2021 looking for studies evaluating intra-thoracic impedance measured by OptiVol with either ventricular tachycardia/ventricular fibrillation (VT/VF) or atrial tachycardia/atrial fibrillation (AT/AF). After extracting the data from each study, we calculated the odds ratio with 95% confidence intervals using RevMan 5 software. Results: Ten studies met our inclusion criteria with a total of 118,504 patients were included in our analysis. Seven studies measured VT/VF included 94,816 patients and 5 studies measured AT/AF included 23,688 patients. Two studies measured both AT/AF and VT/VF. The odds ratio for developing VT/VF with OptiVol fluid index crossing a threshold of 60 Ω-days was 1.55 (95% CI 1.35, 1.78) (P<0.00001) and for developing AT/AF was 1.79 (95% CI 1.43, 2.24) (P<0.00001) {Figure1} Conclusion: The decrease in intra-thoracic impedance measured by OptiVol fluid index threshold crossing of 60 Ω-days is associated with higher risk for developing new onset AT/AF and VT/VF. Key Words: intra-thoracic impedance; OptiVol; tachyarrhythmia Figure1: Forest Plot for risk of developing VT/VF Figure: Forest Plot for risk of developing AT/AF