In a long-term study of the health of the people of in the United States, the U.S. Public Health Service documented the chances of developing heart disease among various groups in the population. Long before the any symptoms appeared, epidemiological research could identify high-risk groups.

Among the highest risk factors are male sex, age over 35, cigarette smoking, high blood pressure, high levels of certain blood fats, and a family history of cardiovascular disorders.

Other researchers have added to this list another risk factor: the compulsive, hard-driving, highly anxious personality. The greater the number of severity, the greater the person’s overall risk.