Late-gadolinium enhancement predicts appropriate device therapies in non-ischemic recipients of primary prevention implantable cardioverter-defibrillators.

Background: Better risk stratification is needed to evaluate patients with non-ischemic cardiomyopathy (NICM) for prophylactic implantable cardioverter-defibrillators (ICD). Growing evidence suggests cardiac magnetic resonance imaging (CMR) may be useful in this regard.

Objective: We aimed to determine if late-gadolinium enhancement (LGE) seen on CMR (dichotomized as none/minimal <2% vs significant ≥2%) predicts appropriate ICD therapies (primary endpoint) and/or all-cause mortality/transplant/left-ventricular assist device (LVAD) implantation (secondary endpoint) in NICM patients.

Methods: We identified 344 patients with NICM who underwent primary prevention ICD implantation at Cleveland Clinic between 2003-2021 with CMR within 12 months before implant. LGE was calculated as percentage myocardium with pixel intensity ≥5 standard deviations higher than that of reference myocardium. Endpoints were adjudicated retrospectively by chart review.

Results: 125 of 344 patients (36%) had none/minimal LGE and 219 (64%) had significant LGE. Over a median follow-up of 61 months, 53 patients (24%) with significant LGE vs 10 (8%) with none/minimal LGE met the primary endpoint, and 56 patients (26%) vs 21 (17%) met the secondary endpoint, respectively. Significant LGE predicted the primary outcome in multivariable competing-risks regression (hazard ratio 2.99, 95% CI 1.48-6.02, p=0.002), but did not predict the secondary outcome in multivariable Cox regression (hazard ratio 1.34, 95% CI 0.78-2.29, p=0.287).

Conclusion: In patients with NICM and a primary prevention ICD, LGE ≥2% is predictive of appropriate device therapies but not all-cause mortality/LVAD/transplant. LGE may be a relatively specific predictor of sudden cardiac arrest risk and therefore could potentially be used during evaluation for prophylactic ICD implantation.