Risk of myocardial infarction attributable to elevated levels of total cholesterol among hypertensives.

BACKGROUND

Although cholesterol is an important risk factor for coronary heart disease (CHD) among hypertensives, the burden of CHD among hypertensives that may be due to elevated cholesterol has not been well documented. This study aimed to estimate the proportion of incident myocardial infarction (MI) among hypertensives that may be attributable to elevated total cholesterol, and to investigate how well the National Cholesterol Education Program Adult Treatment Panel III (ATP III) classification method represents risk of MI among hypertensives.

METHODS

A population-based, case-control study of patients aged 30 to 79 years enrolled in a health maintenance organization, treated pharmacologically for hypertension, and who were not using lipid-lowering medication. Cases were diagnosed with an incident fatal or nonfatal MI between 1986 and 2000 (n = 1535). Controls were randomly sampled and frequency-matched to cases by sex, 10-year age category, and year of event (n = 3743). Subjects' most recent total cholesterol values were categorized according to ATP III guidelines.

RESULTS

Overall, 31% (95% confidence interval: 23-39) of incident MIs among hypertensives could be explained by total cholesterol level above the optimal level of 200 mg/dL. Among participants in the highest ATP III risk stratum, 41% (95% confidence interval: 9-62) of the incident MIs were attributable to total cholesterol levels >160 mg/dL, but total cholesterol >or=200 mg/dL accounted for the majority of these excess events.

CONCLUSIONS

The ATP III risk stratification approach improves detection of the CHD burden due to elevated total cholesterol among hypertensives at highest risk. A strategy to improve cholesterol control in hypertensive patients might prevent a substantial part of the burden of morbidity and mortality from MI.