What underlies NYHA class in elderly patients with heart failure? role of diastolic dysfunction, functional mitral regurgitation and abnormal ventilation during exercise

Abstract

Color-Doppler ecocardiography and cardiopulmonary stress test are pivotal in the evaluation of patients with heart failure. Besides determining systolic function through left ventricular ejection fraction (EF), color-Doppler ecocardiography evaluates the presence and degree of functional mitral regurgitation and the severity of diastolic dysfunction. Moreover, in addition to the aerobic capacity indicated by peak O2 consumption, other parameters of cardiopulmonary stress have proven useful for diagnostic purposes, such as the peak VE/VCO2 ratio or ventilatory efficiency. Since in elderly patients with heart failure the functional impairment often is a combination of the effects of aging with those of disease, the relationship between symptoms, i.e. the NYHA class, ventricular pump function and aerobic performance is sometimes difficult to estabilish. In 60 elderly with systolic heart failure (75 +/- 3 years, EF 30 +/- 6%), we correlated symptoms (i.e. NYHA class) with [1] degree of functional mitral regurgitation (FMR) determined by color-Doppler echocardiography; [2] degree of left ventricular diastolic dysfunction, measured by Doppler analysis of transmitralic and pulmonary veins flow; [3] VO2 and VE/VCO2 at peak exercise at cardiopulmonary test. In all patients, NYHA class was only weakly related with EF and peak VO2, with wide overlap of individual values among patients with different NYHA class. Instead, we observed a tight relationship between NYHA class, FMR degree, and severity of diastolic dysfunction and VE/VCO2 ratio at peak exercise (p<0.001), with a more evident partition among patients in different NYHA classes. In elderly heart failure patients, the reduced effort tolerance expressed by the NYHA classification is only weakly associated with reduced aerobic capacity and pump function, but rather is related with the presence of mitral regurgitation, left ventricular diastolic dysfunction, and a poor ventilatory efficiency during exercise.