Introduction: The clinical course of hypertrophic car-diomyopathy (HCM) is characterized by an extreme heterogeneity with the unpredictable development of heart failure (HF) symptoms in the presence of normal or supranormal left ventricular (LV) ejection fraction (EF). Beyond structural and functional myocardial abnormalities leading to increased LV chamber stiff-ness, impaired LV relaxation, and decreased left atrial (LA) function with elevated LV filling pressures, con-traction dyssynchrony – measurable as LV mechanical dispersion – may play a role in the occurrence of HF symptoms in these patients.
Objective: The aim of our study is to identify the main correlates of heart failure symptoms in patients (pts) with HCM in sinus rhythm and with normal LVEF.
Methods: We have prospectively enrolled 134 patients (52±16 years, 61 men) with HCM. A comprehensive echocardiogram was performed in all, including the measurements of maximal LV and RV wall thickness (WT) and indexed left atrial volume (LAVi). LV filling pressures were assessed using the E/average e’ ratio. Global longitudinal LV strain (GLS), right ventricular strain (RV , using a 6 segments model) and LA strain (LA ) were assessed by speckle tracking echocardio-graphy. LV mechanical dispersion (MD) was calculated as the standard deviation of the time measured from the beginning of the QRS complex to the peak longitu-dinal segmental strain (using the 17 segments LV mo-del). The functional status was defined according to the New York Heart Association (NYHA) classification.
Results: T irtyh-six patients were asymptomatic (NYHA class I), and 98 patients were symptomatic (NYHA class II in 67, class III in 30, and class IV in 1). There were no significant differences between patients with and without HF symptoms regarding: LVWT and RVWT (p>0.05 for both). Symptomatic patients were older (56±16 vs. 43±14, p<0.001), had lower values for LA (p=0.003), RV (p=0.02), GLS (p=0.054), and hi-gher values for LAVi (61±23 vs. 52±18 ml/m2, p=0.03), E/average e’(18.0±8.2 vs. 14.2±6.8, p=0.01), and LVMD (79±31 vs. 63±21ms, p=0.005) compared to asympto-matic patients. Symptomatic patients had more freque-ntly LV outflow tract obstruction than asymptomatic patients (63% vs. 41%, p=0.02). In multivariable ana-lysis, age (OR=1.03, 95% CI 1.001 to 1.070, p=0.04) and LVMD (OR=1.03, 95% CI 1.006 to 1.069, p=0.02) were the only parameters independently correlated with the presence of HF symptoms.
Conclusions: HCM patients with HF symptoms are older and have a more severe LV, RV and LA dysfunc-tion. LVMD was the only echocardiographic parame-ter (structural or functional) related to the presence of HF symptoms. This finding suggests that LVMD may better reflect the complex structural and functional abnormalities seen in HCM.