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 greater-than-or-equal-to 160 mm Hg, a diastolic blood pressure of greater-than-or-equal-to 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, 147; 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.