Noninvasive assessment of left ventricular performance in patients with ischemic heart disease: ear densitographic study during uninterrupted treadmill exercise.
Among 738 consecutive patients with chest pain referred for exercise testing, only 17 men fulfilled strict criteria for this pilot study: (1) achievement of at least 90 percent of age-predicted maximal heart rate or electrocardiographic criteria for a positive test; (2) subsequent coronary angiography; (3) exclusion of prior heart disease; and (4) absence of medication. Measurements of systolic time intervals obtained with ear densitography during early exercise differentiated 10 patients with coronary artery disease (Group 1) from 17 men (7 patients plus 10 normal volunteers) with normal coronary arteries (Group 2). Despite nearly identical heart rate and blood pressure responses in both groups, men in Group 1 had a significantly greater reduction of preejection period (PEP) at 1 minute and 4 minutes as well as a greater decrease in PEP/LVET (left ventricular ejection time) ratio. Differences were most significant when expressed as percent change of PEP/LVET ratio from control value (p less than 0.001 at both 1 minute and 4 minutes). After 4 minutes, men in Group 1 had no further decrease in PEP/LVET ratio and in 8 of the 10 men PEP/LVET ratio then increased to peak exercise. By contrast, PEP/LVET ratio continued to decrease to peak exercise in men in Group 2. The early floor in PEP/LVET ratio in Group 1 represents limited functional reserve and the subsequent increase suggests functional deterioration. Thus, densitographic systolic time interval measurements during uninterrupted exercise in unmedicated subjects appear to improve the sensitivity and specificity of the conventional treadmill test.