Transient reduction of regional myocardial perfusion during angina at rest with ST-segment depression or normalization of negative T waves.

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Abstract
Previous studies showed localized 201Tl defects during resting anginal episodes with ST-segment elevation. Findings of 201Tl during spontaneous angina in 14 patients with ST-segment depression and 7 with normalization of negative T waves are reported. One millicurie of 201Tl was injected i.v. during the ischemic episode and scintigrams were taken within 5-10 min and after 4 h. One week later a new injection of 201Tl in a basal state provided control scintigrams. Early scintigrams showed a regional reduction of 201Tl uptake in all patients with normalization of negative T waves and a close correspondence between the location of the defect and the site of the ECG changes. Scintigrams in patients with ST-segment depression showed a lesser relatively milder reduction of 201Tl activity in 12 and no defect in 2. In these patients the defect, when present, was localized in 8 and diffuse in 4 patients. The site of the 201Tl defect did not always correspond to the location of ST-segment depression. Overall, 4-h scintigrams were similar to those taken in the absence of symptoms. Heart rate and systolic blood pressure measured at the onset of the ECG changes were not significantly different from asymptomatic periods but were significantly lower than during effort-induced angina, so the defects should be related to a reduction of myocardial perfusion, as documented in variant angina, rather than to an inadequate increase of coronary blood flow. Angina at rest with normalization of negative T wave appears related to localized uniform reduction of myocardial perfusion, while angina with ST-segment depression is associated with a less uniform reduction of perfusion, probably located in the subendocardial layers, in the presence of severe coronary lesions.