Prognostic Value of Quantitative Contrast-Enhanced Cardiovascular Magnetic Resonance for the Evaluation of Sudden Death Risk in Patients With Hypertrophic Cardiomyopathy

TLDR

Hypertrophic cardiomyopathy is the leading cause of sudden death in young people, yet many at‑risk patients are not identified, and late gadolinium enhancement on cardiovascular magnetic resonance is an emerging marker of myocardial fibrosis whose role in risk stratification remains unclear. This study evaluated whether the extent of late gadolinium enhancement predicts sudden cardiac death risk in a large cohort of HCM patients. Quantitative late gadolinium enhancement was measured by contrast‑enhanced cardiovascular magnetic resonance to assess myocardial fibrosis burden. Greater LGE extent was independently associated with higher sudden cardiac death risk—each 10% increase in LV mass raised hazard by 46%, ≥15% LGE doubled risk, and LGE improved risk reclassification, while absence of LGE conferred lower risk and predicted end‑stage HCM.

Abstract

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden death in the young, although not all patients eligible for sudden death prevention with an implantable cardioverter-defibrillator are identified. Contrast-enhanced cardiovascular magnetic resonance with late gadolinium enhancement (LGE) has emerged as an in vivo marker of myocardial fibrosis, although its role in stratifying sudden death risk in subgroups of HCM patients remains incompletely understood.We assessed the relation between LGE and cardiovascular outcomes in 1293 HCM patients referred for cardiovascular magnetic resonance and followed up for a median of 3.3 years. Sudden cardiac death (SCD) events (including appropriate defibrillator interventions) occurred in 37 patients (3%). A continuous relationship was evident between LGE by percent left ventricular mass and SCD event risk in HCM patients (P=0.001). Extent of LGE was associated with an increased risk of SCD events (adjusted hazard ratio, 1.46/10% increase in LGE; P=0.002), even after adjustment for other relevant disease variables. LGE of ≥15% of LV mass demonstrated a 2-fold increase in SCD event risk in those patients otherwise considered to be at lower risk, with an estimated likelihood for SCD events of 6% at 5 years. Performance of the SCD event risk model was enhanced by LGE (net reclassification index, 12.9%; 95% confidence interval, 0.3-38.3). Absence of LGE was associated with lower risk for SCD events (adjusted hazard ratio, 0.39; P=0.02). Extent of LGE also predicted the development of end-stage HCM with systolic dysfunction (adjusted hazard ratio, 1.80/10% increase in LGE; P<0.03).Extensive LGE measured by quantitative contrast enhanced CMR provides additional information for assessing SCD event risk among HCM patients, particularly patients otherwise judged to be at low risk.