Transitory appearance of collateral circulation during coronary spasm .

The authors report the case of a patient with coronary spasm characterised on exercise stress testing by an initial depression of the ST segment followed by ST elevation at the 3rd minute of recovery. Coronary angiography showed an important, transient collateral system arising from the left coronary artery, probably minimising the effects of complete occlusion of a dominant right coronary artery. The authors discuss effort-induced spasm and collateral circulation.