Reevaluating exercise intolerance in hypertrophic cardiomyopathy: the role of stress echocardiography combined with cardiopulmonary exercise testing

Abstract Background Dynamic left ventricular outflow tract obstruction (LVOTO) defines obstructive hypertrophic cardiomyopathy (oHCM), while mechanisms of exercise intolerance in non-obstructive hypertrophic cardiomyopathy (noHCM) remain unclear. Cardiopulmonary exercise testing combined with stress echocardiography (CPETecho) enables simultaneous assessment of LVOTO and cardiopulmonary function, providing insights into exercise limitation determinants across hypertrophic cardiomyopathy phenotypes. Objectives To assess CPETecho diagnostic yield for dynamic LVOTO detection and identify distinct exercise intolerance determinants in oHCM versus noHCM. Methods In this multicenter cohort, 195 hypertrophic cardiomyopathy patients underwent maximal semi-supine CPETecho with serial LVOT gradient, pulmonary pressure, and cardiopulmonary evaluations. Exercise intolerance (peak VO₂