Coronary Artery Spasm Induced by Stent Implantation: Studies in a Swine Model

Mechanical stimulation is a known cause of arterial spasm. Since stent implantation in the coronary arteries imparts mechanical trauma, we investigated, in an animal model that simulates human coronary anatomy and physiology, the frequency of occurrence and factors that influence the development of spasm. In 28 Hanford miniature swine, 9 of which were atherosclerotic and 19 of which were nonatherosclerotic, spasm occurred in 15 (54%). Stent-induced spasm directly caused the death of one animal and was implicated in the death of two others. Factors that significantly contributed to coronary spasm were the stent: artery ratio (more spasm with oversized stents) and the size of the artery (more spasm with smaller arteries). There was a trend toward more spasm in atherosclerotic arteries. Spasm occurred despite the use of antispasmodic agents before, during, and after the scenting procedure. Our data suggest that coronary artery spasm may be an important clinical accompaniment to stent implantation in man and may be minimized by the judicious selection of stent size to avoid overdistention of the artery and the avoidance of stent placement in smaller arteries . (J Interven Cardiol 1993; 6:149–155)