Left atrial morpho-functional parameters and their correlation with other phenotypic and functional characteristics of hypertrophic cardiomyopathy

Abstract Background Left atrial (LA) volume index (LAVI), LA reservoir strain (LARS) and total atrial conduction time (TACT) (estimated by tissue Doppler imaging) are morphological and functional parameters reflecting LA structural and electrical remodeling, connected to atrial fibrillation development and heart failure progression in various substrates. In hypertrophic cardiomyopathy (HCM), correlation of the above-mentioned parameters with other disease characteristics is not fully investigated. Purpose Aim of this study was to estimate the prevalence of atrial myopathy characteristics such as increased LAVI, impaired LARS and elongated TACT in a cohort of HCM patients without AF history and investigate their correlation with other phenotypic and functional characteristics of the disease such as left ventricular (LV) hypertrophy magnitude, fibrosis extent and diastolic dysfunction grade. Methods We included 100 HCM patients (54±21 years, 75% male, maximum wall thickness 19±3.4mm) without history of atrial fibrillation who have consecutively undergone 2D-speckle tracking echocardiography and cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE). TACT and LARS measurement is shown on left panel. Burden of fibrosis (percentage of LV mass) was defined by LGE extent (>5 standard deviations compared to nulled myocardium) in CMR slices. Results All HCM patients had preserved EF (60±7.5%), while 28 (28%) presented outflow tract obstruction and 10 (10%) diastolic dysfunction stage≥2. LGE was observed in 64 patients (64%) occupying 8±5% of left ventricular (LV) mass. Mean TACT was 140±22 msec, with LAVI being 32±16 mL/m2 and LARS 26±14%. Among HCM demographic, phenotypic and functional characteristics tested, age and LV mass index were found to be the only independent regressors of TACT (r=0.54, p<0.0005 and r=0.44, p=0.002 respectively, right upper panel), while E/E’ (r=-0.44, p=0.003) and fibrosis extent (r=0.36, p=0.02) were the strongest predictors of LARS and LAVI values respectively (right lower panel). Conclusions Atrial myopathy parameters seem to correlate with various morphological and functional characteristics of HCM. Atrial electro-mechanical delay assessed through TDI based TACT correlates significantly with LVMI, whereas LARS and LAVI are strong regressors of elasticity properties, partially expressed through diastolic function and underlying fibrosis.