Left atrium (LA) size has an important role in determining prognosis and risk stratification in hypertrophic cardiomyopathy (HCM). Cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) is a novel technique for the quantification of LA function. Our aim was first to evaluate LA function by CMR-FT and volumetric analysis in patients with HCM; and secondly we sought to determine the association of LA-longitudinal strain (LA-LS) with major cardiovascular outcomes, particularly all cause mortality and heart failure. 75 patients with HCM and 75 control subjects underwent a conventional CMR study including assessment of LA function by CMR-FT (LA-LS) and volumetric analysis. A primary endpoint of all-cause mortality and secondary combined endpoint of hospital admission related to heart failure, lethal ventricular arrhythmias or cardiovascular death were defined. Compared to controls, LA-LS and all volumetric indices of LA function were significantly impaired in HCM even in patients with normal LA volume and normal LV filling pressures. LA-LS showed moderate-high correlation with LA-emptying fraction (total, active and passive LA-EF, r = 0.68, r = 0.67, r = 0.31, p < 0.001 for all) and with parameters of diastolic function (E/é, r = 0.4, p < 0.001). The age, minimum LA volume and % of LGE were independent predictors of LA-LS (p < 0.01 for all). During a mean follow-up of 3.3 ± 1.2 years LA-LS was associated with the primary (HR: 0.85 (0.73-0.98), p = 0.02) and the secondary end-point (HR: 0.88 (0.82-0.96), p = 0.003). LA-LS by CMR-FT provides accurate measurements of LA function in HCM patients. LA-LS may become a novel potential predictor of poor cardiac outcomes, particularly cardiovascular mortality and HF.
Keywords: Cardiac magnetic resonance; Heart failure; Hypertrophic cardiomyopathy; Left atrial strain; Outcomes.