• stress
• myocardial infarction

Myocardial infarction (MI) is a serious health problem which causes substantial morbidity and mortality. The seriousness of coronary artery disease is heightened by the fact that approximately a third of patients present with sudden death as their first manifestation,¹ and efforts to prevent infarctions before they occur have fuelled an area of research which investigates inciting events, or “triggers”, of MI, arrhythmias, and sudden death. The idea that an MI can be incited by an identifiable event is an old one, but research into cardiovascular triggers has only recently begun to elucidate specific culprits. Triggering research continues to evolve in concert with our understanding of the pathophysiological mechanisms involved in MI, with the eventual hope of developing effective preventive strategies.

The circadian rhythm in the incidence of cardiac events was one of the first triggering patterns to be discovered; peak frequencies of MI and sudden cardiac death were observed in the morning hours after waking.^2,3 Routine activities of daily life such as physical exertion and smoking,⁴ as well as a variety of negative emotions such as anger, tension, and sadness,⁵ were found to induce myocardial ischaemia. Sexual activity doubles the risk of MI, but because of a low absolute baseline risk and infrequent risk exposure, the proportion of MIs actually triggered by sexual activity is low at about 1%.⁶ Investigations into triggering have also extended into disasters, both man-made and natural. Studies have found an increased frequency of sudden cardiac death and MI in relation to catastrophes such as an earthquake⁷ or war,⁸ suggesting that psychological and emotional stress brought on by such disasters can trigger …