Only 17 percent of sudden deaths occurred in the workplace. The authors noted other studies showing coronary artery spasm may be common in Japanese men of middle age and may account for the circadian late night or early morning patterns. Earlier studies have noted the incidence of coronary artery spasm is relatively high in Japanese compared to Caucasians. Coronary spasm occurs most frequently in times of rest, between midnight and early morning, and does not usually occur during daytime exercise. During such spasms, the coronary artery smooth muscle may undergo sudden intense localized contraction, rupturing and extruding vulnerable plaque.
Cigarette smoking is a major risk factor.
As a component in stabilizing heart rhythm and reducing the frequency of coronary artery spasm, the investigators recommended regular exercise. Many have opined that outward displays of hostility or aggression provide healthy outlets for relief of tension and anger. A recent study in the American Heart Association's scientific publication Stroke, calls this advice strongly into question, at least for some individuals. The study involved over 2,000 men in Finland, and the conclusions were made after statistically eliminating other risk factors such as age, smoking, socioeconomic status, etc. One component of anger control may be to avoid routine trigger situations.