ROLE OF SPECTRAL MEASURES OF HEART-RATE-VARIABILITY AS MARKERS OF DISEASE PROGRESSION IN PATIENTS WITH CHRONIC CONGESTIVE-HEART-FAILURE NOTTREATED WITH ANGIOTENSIN-CONVERTING ENZYME-INHIBITORS

Measures of heart rate variability in the frequency domain quantify au tonomic activity. However, the relation of these measures to the sever ity of ventricular dysfunction in patients with congestive heart failu re remains uncertain. We applied spectral analysis of heart rate varia bility to 24-hour Hotter monitor recordings obtained from 20 patients with congestive heart failure who were not treated with angiotensin-co nverting enzyme inhibitors to determine whether significant changes in parameters of heart rate variability reflect the progression of sympt oms in patients with ventricular failure. Both total and low-frequency heart rate spectral power were seen to decrease with worsening New Yo rk Heart Association (NYHA) functional class. A significantly (p=0.04) higher total power was noted in NYHA class II than in class III patie nts (3.0 x 10(-3) +/- 3.6 x 10(-4) and 2.5 x 10(-3) +/- 5.9 x 10(-4) [ beats/min](2), respectively). Similarly, low-frequency heart rate spec tral power was significantly (p=0.008) higher in class II than in clas s III patients (1.7x10(-3)+/-4.6x10(-4) and 1.1x10(-3)+/-3.5x10(-4) [b eats/ min](2), respectively). Only the low-frequency component of the spectrum was directly correlated with left ventricular ejection fracti on (LVEF) (r=0.40) with a trend toward statistical significance (p=0.0 7). Measures of heart rate variability and the changes in autonomic to ne that they reflect may therefore serve as markers of the extent of d isease progression in patients with congestive heart failure.