Exploring physiological determinants of ventilatory inefficiency in hypertrophic cardiomyopathy patients

Abstract Background The role of cardiopulmonary exercise test (CPET) in hypertrophic cardiomyopathy (HCM) has been previously examined, revealing two prognostic parameters: peak Vo2 and the VE/VCO2 slope. Specifically, individuals with a VE/VCO2 value above 31 (ventilator inefficiency) demonstrate a poorer prognosis. Purpose This study aims to analyze the physiological factors contributing to ventilatory inefficiency in individuals with HCM. Methods In this retrospective study, 43 patients HCM patients underwent resting transthoracic echocardiography, CPET combined with echocardiography during physical exertion, and cardiac magnetic resonance imaging. Ventilatory inefficiency was defined as a VE/VCO2 slope exceeding 31, leading to the identification of two groups: Group A (those with ventilatory inefficiency) and Group B (those without ventilatory inefficiency). Results Nine patients exhibited ventilatory inefficiency, while 34 had a normal VE/VCO2 slope. No statistically significant differences were found between the two groups concerning clinical and therapeutic characteristics. Subjects with ventilatory inefficiency showed reduced oxygen pulse (8.3 ± 2.6 vs 11.7 ± 4, p 0.013) and peak VO2 values (13 ± 5 vs 19 ± 5, p 0.005), lower left ventricle global longitudinal strain (-15±3 vs -17± 2, p 0,012), the exertional TAPSE/SPAP ratio (0.46 [0.32-0.48] vs 0.58 [0.47-0.80], p 0.001), exertional TAPSE (23 ± 3 vs 28 ± 4, p 0.001), and indexed stroke volume of the left ventricle assessed by cardiac magnetic resonance imaging (38±8 vs 48±10, p 0.011) (Table 1). The right ventricular function under physical exertion (peak TAPSE and TAPSE/sPAP) and left ventricular functional parameters (index stroke volume and global longitudinal strain) predicted the presence of ventilatory inefficiency. Conclusions This study highlights the role of exertional parameters in the origin of ventilatory inefficiency.Correlation tableFigure with scatter plot