Postural changes in diastolic blood pressure and the risk of myocardial infarction: the Normative Aging Study.

To assess the relationship of postural changes in blood pressure to risk of myocardial infarction, 1359 men were followed for an average of 8.7 years. The men were participants in the Normative Aging Study, a longitudinal study of aging initiated in 1963 at the Veterans Administration Outpatient Clinic in Boston. It was found that the relationship of sitting blood pressure to the subsequent incidence of myocardial infarction was modified by a variable formed by subtracting supine from standing diastolic blood pressure (delta DBP). The effect of sitting diastolic blood pressure on risk of myocardial infarction was confined primarily to men with a delta DBP of 10 mm Hg or more. The effect of sitting systolic blood pressure on risk of myocardial infarction was apparent in all categories of delta DBP (less than 1, 1 to 9, greater than or equal to 10 mm Hg), but the gradient of risk became stronger with increasing levels of delta DBP. The modifying influence of delta DBP remained even when standard coronary risk factors were included in multivariate analyses. These findings suggest a relationship of vascular responsiveness to risk of subsequent myocardial infarction and may have clinical utility.