Heart rate variability and haemodynamic function in individuals with hypertrophic cardiomyopathy

Heart rate variability (HRV) is a measure of cardiac autonomic function. This study: (1) evaluated the differences in HRV and haemodynamic function between individuals with hypertrophic cardiomyopathy (HCM) and healthy controls, and (2) determined the relationship between HRV and haemodynamic variables in individuals with HCM. Twenty-eight individuals with HCM (n=7, females; age 54±15 years; body mass index: 29±5 kg/m ) and 28 matched healthy individuals (n=7 females; age 54±16 years; body mass index: 29±5 kg/m ) completed 5-minute HRV and haemodynamic measurements under resting (supine) conditions using bioimpedance technology. Frequency domain HRV measures (absolute and normalised low frequency power (LF), high frequency power (HF) and LF/HF ratio) and RR interval were recorded. Individuals with HCM demonstrated higher vagal activity (i.e., absolute unit of HF power (7.40±2.50 vs. 6.03±1.35 ms , p=0.01) but lower RR interval (914±178 vs. 1014±168 ms, p=0.03) compared to controls. Stroke volume (SV) index and cardiac index were lower in HCM compared to healthy individuals (SV, 33±9 vs. 43±7 ml‎/beat‎/m², p