Transient microvascular vasoconstriction: a possible cause of unstable angina.

We report the case of a 65-year-old woman who developed unstable angina 2 months after successful coronary angioplasty of the left anterior descending coronary artery. Coronary angiography failed to show angiographic restenosis, but intracoronary ergonovine caused ST segment elevation and her habitual chest pain in the absence of epicardial coronary spasm and important pressure changes in the distal left anterior descending coronary artery assessed by a pressure wire, thus suggesting that distal vessel constriction was responsible for unstable angina.