Does subcutaneous methacholine induce coronary arterial spasm and left ventricular asynergy in patients with Prinzmetal's variant angina?
Methacholine provocation demonstrates that Prinzmetal's variant angina is associated with coronary arterial spasm and regional left ventricular asynergy, even in angiographically normal coronary arteries.
Recently, in Prinzmetal's variant angina, many cases with normal coronary arteries have been reported. The anginal attacks frequently relapse after aortocoronary bypass grafting. It is frequently possible to induce an anginal attack by parasympathomimetic agents such as methacholine and pilocarpine. In this study, methacholine (0.13 mg per kilogram) was injected subcutaneously in three cases of this disease to induce an angina attack, and coronary arteriograms and left ventriculograms were recorded. In all cases a coronary arterial spasm corresponding to the site of the ST-segment elevation in the electrocardiogram was observed. Complete occlusion due to the spasm was observed even in the normal coronary artery. Asynergy was seen in the left ventricular wall corresponding to the site of the ST-segment elevation in the electrocardiogram.
Endo et al. (1976) studied this question.