Subsets of ambulatory myocardial ischemia based on heart rate activity. Circadian distribution and response to anti-ischemic medication. The Angina and Silent Ischemia Study Group (ASIS)

Abstract

Most episodes of ambulatory ischemia are associated with a preceding period of increased heart rate. The likelihood of developing ischemia is predicted by heart rate variables and unaffected by time of day. Anti-ischemic efficacy is generally a result of the medication's efficacy in reducing heart rate variables. A minority of ischemic episodes are not associated with preceding periods of increased heart rate, may be caused by episodic coronary vasoconstriction, and are more effectively reduced by nifedipine than propranolol.