Abstract
BACKGROUND: Male and female patients with hypertrophic cardiomyopathy (HCM) differ in physiologic characteristics and hemodynamics. Little is known about gender-related differences in left atrial (LA) strain and exercise capacity. The aim of this study was to assess the gender-related differences in the relationship between exercise capacity and cardiac function including LA function in patients with HCM. METHODS: Five hundred and thirty-two patients with HCM undergoing exercise stress echocardiography and cardiopulmonary exercise testing (CPET) were prospectively recruited between October 2015 and April 2019 as part of a cohort study in a quaternary referral center. To reduce potential confounding factors, propensity score (PS) matching was performed in 420 patients. LA strain mechanics were evaluated using speckle-tracking echocardiography. RESULTS: The majority of patients were male, comprising 58% of the total. Female HCM patients were older (54±14 vs. 50±15 years, P=0.002). After PS matching, percent-predicted peak VO(2) was similar between the genders (67.5%±20.7% vs. 65.8%±21.8%, P=0.41), even though female HCM patients had lower peak VO(2) (17.7±5.9 vs. 24.1±8.3 mL/kg/min, P<0.001). Left ventricular (LV) diastolic function was worse for female HCM patients. This is shown by worse E/e' ratio (15.0±5.9 vs. 12.9±6.4, P<0.001) and larger LA volume in respect to LV (0.88±0.35 vs. 0.74±0.31, P<0.001), compared with male HCM patients. The gender-related differences in LA reservoir strain were more evident for patients aged 60 years and older (27.5%±8.8% vs. 30.9%±9.1%, P=0.03). LA reservoir strain was found to have a significant association with exercise capacity in both male and female HCM patients (for females, β=0.27, P=0.001; for males, β=0.27, P<0.001), independent of LV diastolic dysfunction and stroke volume. CONCLUSIONS: Gender-related differences in LA reservoir strain were increasingly evident for older HCM patients aged 60 years and older. LA reservoir strain was an independent determinant of percent-predicted peak VO(2) in male and female patients, underpinning the importance of LA function in determining exercise capacity in HCM.