Nitroglycerin-resistant coronary spasm treated with intracoronary linsidomine chlorhydrate (SIN-1)

Spontaneous left anterior descending coronary artery spasm occurred in two patients during coronary angiography. After intravenous injection of 0.75 mg of nitroglycerin, the narrowing was unchanged in one patient and only partially relieved in the other. The coronary narrowing completely disappeared after intracoronary injection of 1 mg of the active metabolite of molsidomine, linsidomine chlorhydrate (SIN-1). In the first patient, this injection was performed just prior to the initiation of coronary balloon dilatation, which was then cancelled. Although rare, these two observations demonstrate the limitations of the intravenous use of nitroglycerin during diagnostic coronary angiography and point out the efficacy of intracoronary administration of SIN-1.