Abstract: The present invention relates to the prevention of coronary artery spasm in mammals by the administration of an effective amount of an antiestrogen compound to block estrogen receptors for the reduction or prevention of the formation of an estrogen--estrogen receptor complex so that estrogen response elements in the DNA of the smooth muscle of the coronary arteries is not activated by the complex. The method of the invention is used to reduce the risk of spasm induced cardiac problems such as sudden infant death syndrome. The antiestrogen is selected from the group consisting of progestins and nonsteroidal antiestrogen compounds.