Temporal variability in wall motion abnormality with stress-induced myocardial ischemia assessed by quantitative exercise echocardiography: difference between reversible and persistent myocardial ischemia

Sensitive method of detecting myocardial ischemia during dobutamine stress echocardiography

To test the hypothesis that dobutamine-induced myocardial ischemia causes early-systolic asynchrony predominantly in the regional left ventricular wall, color kinesis (CK) images during dobutamine stress echocardiography (DSE) were recorded in 13 patients with coronary artery disease and in 10 patients without, all of whom showed normal wall motion at rest. Based on the visual interpretation of DSE and the angiographic findings, 21 segments in the short-axis images at the papillary muscle level were defined as ischemic, and 60 segments of the patients without coronary artery disease were defined as normal. The incremental fractional segmental area change (IFAC) was calculated at 33-ms intervals from the CK images. At the peak dose, IFACs during the first 33 and 33-67 ms were significantly lower in the ischemic segments than in the normal ones, and IFACs during 133-167, 200-233 and 233-267 ms were significantly higher in the ischemic segments. The ratio (peak/low dose) of the cumulative fractional area change at 100 ms gave the best sensitivity (= specificity) for differentiating the 2 groups (86%). Dobutamine-induced ischemia is characterized by an early-systolic asynchrony rather than a change in overall wall excursion and CK can provide an objective assessment of ischemia developing during DSE.

The Sensitivity of Exercise Echocardiography Can Be Improved by Taking the Delayed Myocardial Contraction into Account

The purpose of this study was to test whether the systolic myocardial wall motion abnormalities at the early stages of ischemia are applicable to the diagnosis of coronary artery disease. Forty-four patients with suspected coronary artery disease were studied with the use of low-level exercise echocardiography. Exercise was stopped at the onset of first cardiac symptoms, and no patient exceeded 70% of the age-predicted maximal heart rate level. Forty patients had significant stenosis in at least one coronary artery on coronary angiography. Ten control subjects with a low probability of ischemic heart disease also were studied with exercise echocardiography. The first ischemic wall motion abnormality in systole, defined as delayed onset of the contraction (a regional delay of at least 100 milliseconds in a frame-by-frame analysis of echocardiograms) without any reduction in systolic movement, was regarded separately from hypokinesis (systolic wall motion excursion of less than 5 mm). When the delayed onset of the contraction also was taken into account, 37 of the 40 patients with coronary artery disease had an ischemic response after exercise. The sensitivity of the test thus was 93%. The reduction in systolic wall movement was detected in only 18 of these patients at the exercise level attained (70% or less of age-predicted maximal heart rate). There were two false-positive echocardiograms, but when the control group also was considered, the specificity of the test remained high at 86%. The sensitivity of exercise echocardiography can be increased by paying attention to the delayed onset of the systolic contraction, which occurs at the early stages of ischemia.