The major independent risk factors for coronary heart disease (CHD) are the same in women as in men. These risk factors include age, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol levels, high blood pressure, diabetes mellitus, and smoking. Diabetes appears to be a stronger risk factor in women. In older women, the HDL cholesterol level may be a stronger risk factor than the LDL cholesterol level. In men, risk factors for a second myocardial infarction and death include persistent ischemia, impaired left ventricular function, and ventricular arrhythmias. However, little is known about risk factors for coronary events in women with preexisting coronary disease. Vittinghoff and colleagues used data from the Heart and Estrogen/progestin Replacement Study (HERS) to assess the long-term effect of coronary risk factors and the efficacy of treatments in women with established CHD.

All HERS participants were postmenopausal women with known coronary artery disease who were younger than 80 years and had not undergone hysterectomy. Study participants were randomly assigned to receive combination hormone therapy or placebo. The primary outcome of the HERS study was CHD events (nonfatal myocardial infarction or CHD death).

Increased rates of CHD events were found to be associated with treated diabetes, angina, congestive heart failure, lack of exercise, a history of at least two myocardial infarctions, and nonwhite race. Signs and laboratory results associated with increased risk of CHD events included high blood pressure, high LDL cholesterol levels, low HDL cholesterol levels, high Lp(a) lipoprotein levels, and low creatinine clearance. Alcohol use and regular exercise were associated with lower rates of CHD events. Average annual rates of CHD events increased with the number of risk factors.

The HERS study also documented the underuse of medications for secondary prevention of CHD events in this population of women. On enrollment, most of the women were taking aspirin (83 percent), but fewer were receiving beta blockers (33 percent) or lipid-lowering agents (53 percent), primarily statins, to lower elevated cholesterol levels. By the end of the study, aspirin use had declined slightly (79 percent), beta-blocker use had remained about the same (35 percent), and use of lipid-lowering medications had increased (66 percent). Other preventive measures, including angiotensin-converting enzyme inhibitors, blood pressure and weight control, diet, exercise, and smoking cessation, also were underused. Women with five or more risk factors appeared to be least likely to receive aspirin and lipid-lowering therapy.

The authors conclude that multiple, easily assessed risk factors predict a higher rate of CHD events in women with known coronary disease, and that these risk factors differ from those in primary prevention. There is also significant underuse of preventive treatments.

In an editorial in the same issue, Miller and Oparil note that despite some limitations, HERS provided some useful information on secondary prevention strategies. Results from the study did not support the cardioprotective effects of hormone therapy in postmenopausal women. Furthermore, the study confirmed that women with CHD are being undertreated. The authors of the editorial noted various measures that have been effective in secondary prevention and urged their implementation.