MP-453090-11 HIBERNATING MYOCARDIUM IS ASSOCIATED WITH A LOWER INCIDENCE OF SUSTAINED VENTRICULAR ARRHYTHMIAS IN PATIENTS WITH ISCHEMIC CARDIOMYOPATHY

Abstract

Prognostic markers for the prediction of major arrhythmic events (MAE) in patients with ischemic cardiomyopathy (ICM) are scarce. Although myocardial scar is associated with ventricular arrhythmias (VA), the role of hibernating myocardium (HM) is unclear. The aim of this study was to identify prognostic markers for MAE using positron emission tomography (PET) in patients with ICM. In this retrospective single-center study, consecutive patients with ICM confirmed by invasive coronary angiography undergoing both 13N-ammonia (NH3) and 18F-fluorodeoxyglucose (FDG) scan for evaluation of myocardial ischemia and HM were assessed for the occurrence of MAE after PET scan of sudden cardiac death (SCD), survived SCD, VA requiring external or ICD shock, antitachycardia pacing (ATP) or sustained VA during follow-up. PET scan was performed in 254 with ICM and they were followed up for a median of 5.4 years (IQR 3.6-9.8). Mean age was 65.6 years (±10.9), mean ejection fraction was 36.2% (±12.1), 69 patients (27%) had an ICD at baseline, 39 (56.5%) for primary prevention. PET scan revealed myocardial ischemia, scar (=NH3-PET resting perfusion defect) and HM in 94 (37%), 229 (90.2%) and 121 (47.6%) patients, respectively. Mean left ventricular (LV) scar size was 23.5% (±13.5) and mean HM size 8.1% (±7.6). MAE after PET scan occurred in 34 patients (13.4%); 18 patients (7%) suffered SCD, 19 patients had sustained VA, 4 (1.6%) an external, 4 (1.6%) an ICD shock and 12 (4.7%) received ATP. Median time to MAE was 2.5 years (IQR 1-3.9). Scar >10% detected by NH3-PET scan was associated with a higher incidence of MAE (HR 1.24, CI 1.21-9.82, p=0.02) compared to ≤10%. HM >10% detected by FDG-PET scan in patients with scars >10% had lower incidence of MAE (HR 0.89, CI 0.18-0.93, p=0.033) compared to HM ≤10% or scar ≤10%, even after adjusting for LVEF ≤35%. This association remained significant when patients (n=49) revascularized within 90 days of PET scan were censored at the time of revascularization. There was no significant association between MAE and myocardial ischemia (HR 0.84, CI 0.42-1.7, p=0.63), independent of any revascularization. Patients with large and non-viable myocardial scars are at increased risk for MAE. Large (>10% of LV), but viable scars carry similar risk of MAE as smaller (≤10% of LV) scars. The combination of cardiac NH3 and FDG PET scans may serve as a prognostic tool for the prediction of clinically important endpoints such as SCD and sustained VA.