Systolic blood pressure levels among adults with hypertension and incident cardiovascular events: the atherosclerosis risk in communities study.

Abstract

Studies document a progressive increase in heart disease risk as systolic blood pressure (SBP) rises above 115 mm Hg, but it is unknown whether an SBP lower than 120 mm Hg among adults with hypertension (HTN) lowers heart failure, stroke, and myocardial infarction risk. To examine the risk of incident cardiovascular (CV) events among adults with HTN according to 3 SBP levels: 140 mm Hg or higher; 120 to 139 mm Hg; and a reference level of lower than 120 mm Hg. A total of 4480 participants with HTN but without prevalent CV disease at baseline (years 1987-1989) from the Atherosclerosis Risk in Communities Study were included. Measurements of SBP were taken at baseline and at 3 triennial visits; SBP was treated as a time-dependent variable and categorized as elevated (≥140 mm Hg), standard (120-139 mm Hg), and low (<120 mm Hg). Multivariable Cox regression models included baseline age, sex, diabetes status, BMI, high cholesterol level, smoking status, and alcohol intake. Incident composite CV events (heart failure, ischemic stroke, myocardial infarction, or death related to coronary heart disease). After a median follow-up of 21.8 years, a total of 1622 incident CV events had occurred. Participants with elevated SBP developed incident CV events at a significantly higher rate than those in the low BP group (adjusted hazard ratio [HR], 1.46; 95% CI, 1.26-1.69). However, there was no difference in incident CV event-free survival among those in the standard vs low SBP group (adjusted HR, 1.00; 95% CI, 0.85-1.17). Further adjustment for BP medication use or diastolic BP did not significantly affect the results. Among patients with HTN, having an elevated SBP carries the highest risk for cardiovascular events, but in this categorical analysis, once SBP was below 140 mm Hg, an SBP lower than 120 mm Hg did not appear to lessen the risk of incident CV events.