Abstract 12440: Does Low Diastolic Blood Pressure Contribute to the Risk of Recurrent Cardiovascular Disease Events? The Framingham Heart Study

Abstract

Background: The clinical significance of low diastolic blood pressure (DBP) as a risk for recurrent cardiovascular disease (CVD) events in persons with isolated systolic hypertension (ISH) is controversial. Methods: We examined risk for recurrent CVD events in 791 individuals (age 75 years, 47% female, mean follow-up time: 8±6 years) with DBP<70 (N=225) versus 70-89 mmHg (N=566) following initial CVD events in the original and offspring cohorts of the Framingham Heart Study. Results: Recurrent CVD events occurred in 153 (68%) participants with lower DBP and 271 (48%) with higher DBP (p<0.0001). Risk of recurrent CVD events in risk factor-adjusted Cox regression was higher in those with DBP<70 mmHg versus DBP 70-89 mmHg in both treated [HR, 5.1 (95% CI: 3.8-6.9) p<0.0001] and untreated individuals [HR, 11.7 (6.5-21.1) p<0.0001] (treatment interaction: p=0.10). Individually, coronary heart disease, heart failure, and stroke recurrent events were more likely with DBP<70 mmHg versus 70-89 mmHg (p<0.0001). To judge the potential modifying effect of wide pulse pressure (PP) on excess risk associated with low DBP, we defined 4 binary groupings of median PP (≥ 68 verses <68 mmHg) and categorical DBP (<70 versus 70-89 mmHg), and found that CVD event rates were higher only in the group with wide PP and DBP<70 mmHg (Chi Square = 32.6, p<0.001, see Figure). Conclusions: Persons with ISH and initial CVD events have increased risk for recurrent CVD events in the presence of DBP<70 mmHg versus DBP 70-89 mmHg, supporting wide PP as an important risk modifier of the adverse effect of low DBP; we postulate increased CVD risk is related to the pernicious effects of faulty microvascular function resulting from increased elastic artery stiffness in combination with low diastolic perfusion pressure.