Slow filling period/rapid filling period ratio in the apexcardiogram: relation to the diagnosis of coronary artery disease.

Apexcardiograms were performed in 68 consecutive patients who had either normal findings or coronary artery disease on cardiac catheterization. The height of the a wave in relation to the total apexcardiographic deflection (a/H) and the duration of both the rapid (RFW) and the slow (SFW) filling periods were determined in each case. The patients were classified into three gorups: I, no evidence of heart disease on catheterization; II, significant coronary artery disease with elevated left ventricular end-diastolic pressure; and III, coronary artery disease with normal filling pressure. There was a significant difference (P less than 0.001) between the SFW/RFW values (mean +/- 1 standard deviation) in control subject (group I, 2.3 +/- 0.5) and in subjects with coronary artery disease (group II, 4.7 +/- 1.6 and group III, 4 +/- 1.7). Setting the upper limit of normal for SFW/RFW at 2.8 (mean + 1 standard deviation) identified 94 percent of patients, in group II, 71 percent of patients in group III and 86 percent of all patients with coronary disease (group II plus group III). This sensitivity appeared greater than that of the a/H ratio. Only 2 of 17 patients (12 percent) without coronary atherosclerosis had an SFW/RFW ratio greater than 2.8. It is concluded that (1) the slow/rapid filling period ratio is a useful noninvasive measurement for identifying subjects with ischemic heart disease; (2) the increased values for slow/rapid filling period ratio associated with obstructive coronary lesions may be caused by impairment of early left ventricular distensibility; and (3) this ratio should be determined in patients with other forms of heart disease to determine its specificity.