Altered myocardial perfusion during dobutamine stress testing in silent versus symptomatic myocardial ischaemia assessed by quantitative MIBI SPET imaging.

The aim of the study was to compare the extent and severity of reversible underperfusion in silent versus painful myocardial ischaemia during the dobutamine stress test. A consecutive series of 85 patients with significant coronary artery disease and reversible perfusion defects on technetium-99m methoxyisobutylisonitrile single-photon emission tomography performed at rest and during high-dose dobutamine stress (up to 40 microg kg-1 min-1) were studied. The left ventricle was divided into six segments. An ischaemic perfusion score was derived quantitatively by subtracting the rest from the stress defect score. Patients with multivessel disease had a higher ischaemic score (610+/-762 vs 310+/-411, P<0. 05) and a higher number of reversible perfusion defects (2.1+/-1.2 vs 1.1+/-0.8, P<0.01) than patients with single-vessel disease. Typical angina occurred in 37 patients (44%) during the test. There was no significant difference between patients with and patients without angina with respect to age, gender, peak rate-pressure product, prevalence of previous myocardial infarction, diabetes mellitus, multivessel disease or number of stenotic coronary arteries. Stress, rest and ischaemic scores as well as the number and distribution of reversible defects were not different in patients with and patients without angina. Patients with angina more frequently had a history of typical angina before the test (43% vs 17%, P<0.01) and ST-segment depression during the test (54% vs 25%, P<0.01). It is concluded that in patients with coronary artery disease and ischaemia detected by dobutamine scintigraphy, the extent and severity of coronary artery disease and myocardial perfusion abnormalities are similar with or without angina during stress testing.