The natural history of borderline isolated systolic hypertension

Abstract

Background: Patients with isolated systolic hypertension are at increased risk for cardiovascular disorders. We attempted to determine whether those with borderline isolated systolic hypertension (defined as a systolic blood pressure of 140 to 159 mm Hg and a diastolic blood pressure below 90 mm Hg) have a greater risk of progression to definite (more severe) hypertension and of major morbid or fatal events than people with normal blood pressure (< 140/90 mm Hg).

Methods: A total of 2767 of the original participants in the Framingham Heart Study were monitored with biennial examinations for up to 34 years for the development of definite hypertension (defined as a systolic blood pressure of > or = 160 mm Hg, a diastolic blood pressure of > or = 90 mm Hg, or the initiation of antihypertensive therapy) and for major cardiovascular events.

Results: Borderline isolated systolic hypertension was the most common type of untreated hypertension among adults over the age of 60. After 20 years of follow-up, 80 percent of those with borderline isolated systolic hypertension had progression to definite hypertension, as compared with 45 percent of the normotensive participants (P < 0.001). After adjustment for age, sex, and risk factors for cardiovascular disease, participants with borderline isolated systolic hypertension had an excess long-term risk of cardiovascular disease (hazard ratio, 1.47; 95 percent confidence interval, 1.24 to 1.74) and death from cardiovascular disease (hazard ratio, 1.57; 95 percent confidence interval, 1.24 to 2.00), as compared with normotensive participants. In an analysis of pooled data from biennial examinations to study short-term sequelae, subjects with borderline isolated systolic hypertension had an increased risk of progression to definite hypertension (odds ratio, 3.84; 95 percent confidence interval, 3.35 to 4.41) and of cardiovascular disease (odds ratio, 1.39; 95 percent confidence interval, 1.06 to 1.82).

Conclusions: In both the short term and the long term, subjects with borderline isolated systolic hypertension are at increased risk of progression to definite hypertension and the development of cardiovascular disease.