Left atrial strain predicts adverse events in hypertrophic cardiomyopathy: preliminary results from a CMR study

Abstract

Abstract Background Hypertrophic cardiomyopathy (HCM) is associated with an increased risk of major adverse cardiovascular events (MACE), however, current risk stratification methods are imperfect. Left atrial global longitudinal strain (LA GLS) is an increasingly acknowledged predictive parameter, yet its potential role in HCM is not well defined. Purpose This study aims to investigate the prognostic role of cardiac magnetic resonance (CMR)-derived LA GLS for the occurrence of MACE in patients with HCM. Methods A retrospective, single-centre, CMR study of HCM patients was conducted. Clinical data was collected from electronic medical record and CMR images were analysed by two blinded investigators. LA GLS was derived from CMR two-chamber cine images by a semiautomatic method, and was categorized according to its median value. The endpoint was a composite of MACE, including all-cause death, sudden cardiac death (SCD), sustained and non-sustained ventricular tachycardias (VT), appropriate implantable cardiac defibrillator (ICD) shocks, heart failure (HF) hospitalization, and new-onset atrial fibrillation (AF). Cox regression analysis was performed. The preliminary results of the study are now reported. Results A total of 54 HCM patients were included, mean age was 58.5 years ± 15.9 and 38.9% were female. Average maximal wall thickness (MWT) was 18.0 mm ± 3.9, 37% had left ventricular outflow obstruction (LVOTO) and 45.1% had positive late gadolinium enhancement (LGE). After a mean follow-up of 6.9 ± 3.0 years, 26 patients (48.1%) experienced the composite endpoint. Figure 1 shows the clinical and CMR differences according to the occurrence of MACE. LA GLS was significantly lower in patients with MACE compared to those without (26.5 ± 19% vs 36.7 ± 13%, p=0.026), with a moderate predictive value (AUC = 0.68, Figure 2A). Multivariate Cox regression analysis revealed that a decrease in LA GLS (HR 1.09 per each 1% decrease, 95% CI 1.03-1.15, p=0.002), the presence of LGE (HR 6.9, 95% CI 1.7-28, p=0.007), the presence of LVOTO (HR 3.4, 95% CI 1.12-10.2, p=0.031) and an increase in MWT (HR 1.23 per each 1mm increase, 95% CI 1.05-1.45, p=0.011) were independently associated with MACE. Among low-risk HCM patients (absence of LGE or LVOTO, or MWT below our median value), LA GLS had an additional prognostic role, and those with an LA GLS above the median value (LA GLS>29.7%) presented a remarkably favourable prognosis (Figure 2B-D). Conclusions CMR-derived LA GLS is a predictor of outcomes in HCM beyond established imaging prognostic factors. Particularly, LA GLS appears to be useful in risk-stratifying low-risk HCM patients: those with normal LA GLS show an excellent prognosis. If confirmed in larger studies, LA GLS could be used to individualise HCM management.Figure 2