Repetitive squatting exercise as a diagnostic predictor in patients with dilated cardiomyopathy

OBJECTIVES: Non-ischaemic dilated cardiomyopathy (DCM) is characterised by a highly variable disease progression. Stress echocardiography and cardiopulmonary exercise testing (CPET) are beneficial in risk assessment, but are labour intensive. Repetitive squatting and standing without weights is a simple exercise (EX). The aim of this study was to investigate the prognostic role of left ventricular (LV) contractile recruitment (CR) after a simple EX of repetitive squatting through three-dimensional (3D) echocardiography. METHODS: Patients with DCM (LV ejection fraction (EF)<50%, n=68) and age-matched healthy volunteers (n=25) received a 3D echocardiographic evaluation of LV EF before and after 30 repetitions of squatting-standing EX. CR was defined by the change of LV EF (Δ>4%). Patients were followed up prospectively (2 years) for cardiac death and deteriorating heart failure. RESULTS: During follow-up, 14 cardiac events occurred (21%) with six deaths and eight severe heart failure deteriorations. A poor CR after squatting EX differentiated DCM patients with cardiac events during follow-up as accurately as a reduced peak oxygen consumption (peak VO (2)<20 mL/kg/min) (sensitivity: 0.97 and 0.95). Both had a significant incremental diagnostic value over clinical (age, dyspnoea and natriuretic peptide level) or resting echocardiographic parameters (E/E’ ratio, LV EF and end-diastolic LV volume) to predict cardiac events (global χ(2): 16.0 vs 5.3; 19.5 vs 6.1; P<0.01 for all). CONCLUSIONS: The presence of LV CR after EX of repetitive squatting without weights can stratify risk and predict cardiac events in patients with DCM as correct as CPET.