Resting heart rate and cardiac function in dilated cardiomyopathy.

We hypothesized that, within the normal range of resting heart rate, heart rate and left ventricular ejection fraction would be inversely correlated and heart rate and left ventricular filling would be correlated in patients with dilated cardiomyopathy and not correlated in patients with normal cardiac function. At rest, heart rate, left ventricular ejection fraction, and three measures of diastolic filling (time to peak filling rate, peak filling rate, and first half filling fraction) were recorded using radionuclide ventriculography in subjects with no cardiac disease, patients with idiopathic dilated cardiomyopathy, and patients with dilated cardiomyopathy associated with ischemic heart disease. Heart rate had significant inverse correlations with left ventricular ejection fraction (r=-0.55, P=0.0007) and time to peak filling rate (r=-0.47, P=0.005) and a positive correlation with peak filling rate (r=0.73, P<0.0001) in patients with idiopathic dilated cardiomyopathy; heart rate was correlated only weakly with these measures in the absence of cardiac disease and essentially was not correlated in dilated cardiomyopathy due to ischemic heart disease. The change in resting heart rate with left ventricular ejection fraction and time to peak filling rate were significantly (P<0.05) different between patients with no cardiac disease and those with idiopathic dilated cardiomyopathy. Thus, resting heart rate correlated significantly with left ventricular ejection fraction and diastolic filling in patients with idiopathic dilated cardiomyopathy.