[Spasm of the coronary arteries]

Spontaneous spasm and methylergometrine maleate-provoked spasm are defined, the latter being observed in nearly all cases of so-called Prinzmetal angina, in approximately one out of three cases of angina at rest, and a certain number of cases of unstable angina: it has even been demonstrated during effort tests with coronarography. Several studies have demonstrated its possible implication in myocardial infarction. Continuous electrocardiogram recordings and isotopic studies have also shown the frequency of silent spasms, or those associated with other ECG modifications than an increased STT latency period. It is now well-established that this type of angina is provoked by reduction in myocardial oxygen supply. To explain the triggering mechanism of the spasm, various factors have been successively evoked: alpha- and beta-receptor disequilibrium, a vagal effect, the very important role played by thromboxane A2 of platelet origin. Emphasis is also placed on circadian variations observed during the spasm, but the course of spastic angina is often unpredictable, leading to necrosis or sudden death in a fairly large number of cases. Medical treatment is essentially by long-acting nitrate derivatives and calcium inhibitors (beta-blockers are considered, according to different teams, as being useless or even dangerous). Surgical treatment may be by aortocoronary shunt or transluminal angioplasty in cases that are stable with trinitrate compounds; associated plexectomy has given good results according to teams in Lille; while heart transplantation has been performed in rare cases. Choice of therapy is difficult in cases with apparently non-surgical moderate stenosis and recurrent spastic angina.