49Tachyarrhythmias in adults with previous rastelli repair: mechanistic insights from single center expereince.

INTRODUCTION: Late arrhythmias are common in adults undergoing Rastelli repair with a right ventricle (RV) to pulmonary artery (PA) conduit. The mechanism of arrhythmias has not been described. We sought to describe the prevalence, clinical predictors and mechanisms of supraventricular (SVT) and ventricular tachycardia (VT) in this population.

METHODS: We retrospectively reviewed charts for adults (age >18 years) with discordant ventriculo-arterial connection (d-TGA (and double outlet RV), VSD and pulmonary stenosis (PS) that underwent Rastelli operations who were seen in our clinic. Twenty-nine patients (pts) [median age 28 (IQR 15) yrs, 59% male] were included.

RESULTS: Over median post-operative follow-up of 22 (IQR 9) yrs, 10 pts had arrhythmia (SVT=7, VT=1, both= 2). The median age at arrhythmia onset was 28 (IQR 11) yrs. Pts with arrhythmias were older than those without [36 (14) vs 24 (12) yrs, p=0.005] with greater time since surgery [26 (9) vs 19 (7) yrs, p=0.01]. The number of surgical interventions post-Rastelli [2 (2) vs 2 (1)], the LV and RV systolic function at last follow-up, the right ventricular size and systolic pressure, and the severity of pulmonary regurgitation grade were similar between pts with and without arrhythmias. The median follow-up time from arrhythmia onset was 4.5 (IQR 11) yrs. The majority of pts with SVT (7/9) were managed with medications. Two pts with SVT had catheter ablation. Both pts had multiple intra-atrial reentrant tachyarrhythmia (IART) (cavo-tricuspid isthmus dependent and incisional IART); more than one procedure was required to eliminate all IART. Two pts with VT were drug refractory and had ablation. One pt had a macro-reentrant VT around the RV-PA conduit (Figure 1A); the VT terminated during ablation with no recurrence after 9 years. The second pt underwent ablation twice with a focal/micro-reentrant VT- source from scar at the base of RV-PA conduit (Figure 1B) with no recurrence 8 months after the 2(nd) procedure.

CONCLUSIONS: Tachyarrhythmias were seen in ≥ 1/3 of adults with Rastelli repair. The prevalence of arrhythmias increased with age. The mechanisms of SVT included CTI-dependent and incisional RA scar IART. The mechanisms of VT were macro-reentrant and focal, both originating around RV-PA conduit junction.