Prediction of major arrhythmic outcomes in ischaemic cardiomyopathy: value of hibernating myocardium in positron emission tomography/computed tomography

Abstract

Abstract Aims Known predictors of major arrhythmic events (MAEs) in patients with ischaemic cardiomyopathy (ICM) include previous MAE and left ventricular ejection fraction (LVEF) ≤ 35%. Myocardial scars detected by perfusion imaging in ICM have been linked to MAE, but the prognostic significance of hibernating myocardium (HM) is unclear. The objective was to predict MAEs from combined 13N-ammonia (NH3) and 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in ICM. Methods and results Consecutive patients with ICM undergoing combined NH3- and FDG-PET/CT were included. HM was quantified in relation to total left ventricular myocardium (i.e. ≥7% is large). The primary outcome was MAEs [sudden cardiac death, implantable cardioverter defibrillator (ICD) therapy, and sustained ventricular tachycardia/fibrillation]. Among 254 patients, median baseline LVEF was 35% [interquartile range (IQR) 28–45] and 10% had an ICD. PET/CT identified ischaemia in 94 (37%), scar in 229 (90%), and HM in 195 (77%) patients. Over a median follow-up of 5.4 (IQR 2.2–9.5) years, MAE occurred in 34 patients (13%). Large HM was associated with a lower incidence of MAE (hazard ratio 0.31, 95% confidence interval 0.1–0.8, P = 0.001). After multivariate adjustment for history of MAE, LVEF ≤35%, and scar ≥10%, large HM remained significantly associated with a lower incidence of MAE (P = 0.016). LVEF improved over time among patients with large HM (P = 0.006) but did not change in those without (P = 0.610) or small HM (P = 0.240). Conclusion HM conveys a lower risk of MAE in patients with ICM. This may be explained by an increase in LVEF when a large extent of HM is present.