Jonathan Chrispin

Ventricular tachycardia and sudden cardiac death remain the principal late causes of mortality in repaired tetralogy of Fallot. Clinical practice is evolving from a “reactive” paradigm centered on defibrillator therapy and post-event ablation toward a “proactive” paradigm targeting slowly conducting anatomical isthmuses before clinical arrhythmias become manifest. Monomorphic ventricular tachycardia in this population typically occurs due to a discrete, anatomically defined set of slowly conducting isthmuses bounded by surgical patches or incisions and valve annuli. Substrate-targeted catheter and surgical ablation are technically feasible, safe, and associated with high arrhythmia-free survival when complete bidirectional block is achieved. The current indication for “proactive” ablation is for substrate evaluation before transcatheter pulmonary valve replacement, after which endocardial access to the dominant isthmus may be permanently obscured. Pulmonary valve replacement alone does not abolish the arrhythmogenic substrate, thus providing the rationale for combining valve intervention with proactive ablation. This narrative review discusses substrate biology, risk stratification, comparative outcomes of reactive and proactive ablation strategies, and the role of pulmonary valve replacement. It also proposes an operational pathway integrating both approaches within shared decision-making. The ongoing CATAPULT-TOF study and subsequent multicenter work will determine the populations in which proactive substrate evaluation should become routine.

Objectives: To evaluate the clinical outcomes of patients with cardiac sarcoidosis (CS) undergoing cardiac resynchronization therapy (CRT) among a cohort of patients with CS and cardiac implantable electronic devices. Background: CS manifests with conduction abnormalities, ventricular arrhythmias (VA), and heart failure (HF). While CRT improves outcomes in select nonischemic cardiomyopathies, its specific role in CS-related cardiomyopathy remains unclear. Methods: This retrospective cohort study included patients from the Johns Hopkins Cardiac Sarcoidosis Program (2004–2024) with a clinical or histological CS diagnosis who underwent ICD or pacemaker implantation, with or without CRT. Outcomes assessed included HF hospitalizations, appropriate anti-tachycardia pacing (ATP) or ICD shocks, heart transplantation, all-cause mortality, and a composite of these measures. Results: Among 212 patients (40.1% female, mean age 52.8 ± 11.1 years), 85 received CRT (82 CRT-D, 3 CRT-P). CRT recipients had significantly lower baseline left ventricular ejection fraction (LVEF) than non-CRT patients (mean difference: 11%; P < .01) but demonstrated greater LVEF improvement over time (1.43%; P = .03). During a follow-up of 6.15 ± 4.43 years, HF hospitalizations occurred in 12.7%, ATP/ICD shocks in 40.6%, and death in 8.0%. Composite outcomes occurred in 48.5% with no significant differences between CRT and non-CRT groups ( P = .50). CRT patients had lower freedom from HF hospitalizations ( P = .01) but similar arrhythmia treatment rates ( P = .70). Conclusions: CRT in CS was associated with improved LVEF but higher HF hospitalization rates and comparable VA treatment outcomes. These findings highlight the need for further research to optimize CRT utilization in this population.