Ventricular arrhythmias associated with left ventricular noncompaction: Electrophysiologic characteristics, mapping, and ablation

BACKGROUND Left ventricular noncompaction (LVNC) is a primary cardiomyopathy that can present with recurrent ventricular arrhythmias (VAs). Data on the benefit of catheter ablation of VAs in LVNC are lacking. OBJECTIVE The purpose of this study was to describe the electrophysiologic features and outcomes of catheter ablation of VAs in LVNC. METHODS The cohort consisted of 9 patients (age 42 +/- 15 years) with diagnosis of LVNC based on established criteria and VA (ventricular tachycardia [VT] in 3 and frequent premature ventricular contractions (PVCs) in 6) despite treatment with a mean of 2 +/- 1 antiarrhythmic drugs. Ablation sites were identified using a combination of entrainment, activation, late/fractionated potential ablation, and pace-mapping. RESULTS A total of 8 patients (89%) had left ventricular (LV) systolic dysfunction (mean ejection fraction 40% +/- 13%). Patients who presented with VT had evidence of abnormal electroanatomic substrate involving the mid- to apical segments of the LV, which matched the noncompacted myocardial segments identified by preprocedural magnetic resonance imaging or echocardiography. In patients presenting with frequent PVCs, the site of origin was identified at the papillary muscles (50%) and/or basal septal regions (67%). After median follow-up of 4 years (range 1-11) and a mean of 1.8 +/- 1.1 procedures, VAs recurred in 1 patient (11%). Significant improvement in LV function occurred in 4 of 8 cases (50%). No patients died or underwent heart transplantation. CONCLUSION The VA substrate in patients with LVNC and VT typically involves the mid-apical LV segments, whereas focal PVCs often arise from LV basal-septal regions and/or papillary muscles. Catheter ablation is safe and effective in achieving good VA control over long-term follow-up in most patients.