Angina Pectoris Associated with ST Segment Elevation in the Absence of Epicardial Coronary Arterial Obstruction

Two cases are presented in which angina pectoris associated with ST segment elevation occurred during either an ergonovine provocation test or coronary angioplasty, despite the absence of epicardial coronary artery obstruction. In both cases, no epicardial coronary spasm, thromboembolic occlusion, coronary air embolus, vessel dissection, or side-branch occlusion was observed. These findings suggest that transmural myocardial ischemia without epicardial coronary artery obstruction can occur owing to abnormalities of the coronary microcirculation. Microvascular vasoconstriction leading to transmural myocardial ischemia may be induced by ergonovine or by the release of potent vasocon strictors from disrupted coronary lesions during angioplasty.