Cardiac magnetic resonance-derived left atrial strain restratifies patients with hypertrophic cardiomyopathy at low-risk of sudden cardiac death

AIMS: Hypertrophic cardiomyopathy (HCM) is associated with diverse cardiovascular outcomes. Whilst the HCM Risk-SCD score effectively stratifies sudden cardiac death (SCD) risk, it provides limited insight into global cardiovascular prognosis, particularly amongst low-risk patients (HCM Risk-SCD score <4%). Left atrial global longitudinal strain (LA-GLS), derived from cardiovascular magnetic resonance (CMR), may enhance risk stratification. This study aimed to assess the prognostic value of CMR-derived LA-GLS in predicting major adverse cardiovascular events (MACE) in a cohort of low-risk HCM patients. METHODS AND RESULTS: In this retrospective longitudinal single-centre study, 183 low-risk HCM patients underwent CMR with LA-GLS assessment via feature tracking. The primary endpoint was a composite of MACE, including ventricular arrhythmias, heart failure, thromboembolic events, or all-cause death. The mean age was 64 ± 19 years; 47% were female. Over a median follow-up of 6.1 (2.8-8.5) years, 67 patients (37%) experienced MACE. The variables associated with MACE after adjustment were LA-GLS (HR 2.17, 95% CI 1.31-3.58, P = 0.002), maximal left ventricular (LV) wall thickness (HR 1.10, 95% CI 1.02-1.18, P = 0.015), late gadolinium enhancement (LGE) > 5% of total myocardial mass (HR 2.00, 95% CI 1.01-3.97, P = 0.049), and LV ejection fraction (LVEF) < 50% (HR 12.86, 95% CI 5.91-33.66, P < 0.001). Patients with LVEF >50%, LGE <5%, and an LA-GLS >37.6% had a MACE rate of only 2%, identifying an overall low-risk subgroup. The prognostic value of LA-GLS was validated in an external cohort of 202 low-risk HCM patients. CONCLUSION: CMR-derived LA-GLS improves risk stratification in HCM patients at low-risk of SCD and may refine management strategies and optimize resource allocation.