Relationship between components of heart rate variability and Doppler echocardiographic indices of left ventricular systolic performance in patients with coronary artery disease

Decreased heart rate variability (HRV) has been reported as prognostic predictor in coronary artery disease population. The aim of the study was to assess the relationship between cardiac autonomic tone disturbances and the degree of left ventricular dysfunction, estimated by 2-dimensional and Doppler echocardiography, in patients with coronary artery disease. Forty patients with angiographically proven coronary artery disease and 15 age- and sex-matched healthy subjects were included into the study (Group I and II, respectively). Routine clinical examinations, electrocardiography, coronary angiography, and 2-dimensional and Doppler echocardiography with assessment of LV systolic performance were done in all the patients and control subjects. Cardiac autonomic function was assessed by means of frequency- domain analysis of heart rate variability. The powers of LF and HF bands (P1 and P2), their ratio (P1/P2), and the logarithmic expression of powers were measured. The patients (Group I) had lower values of parasympathetic band of HRV and higher sympathetic activity than the healthy population (Group II) (p < 0.0002 for P2 and p < 0.04 for P1/P2 ratio). A positive significant correlation was seen between parasympathetic band of HRV and ejection fraction (r = 0.61, p < 0.0001), and mean acceleration of aortal flow (r = 0.56, p < 0.0001), whereas P1/P2 ratio inversely and significantly correlated with the same parameters (r = -0.46, p < 0.002 and r = -0.41, p < 0.008)