Systolic and Diastolic Blood Pressures and Cardiovascular Outcomes
- In a retrospective re-analysis of data from ALLHAT, the risks for adverse cardiovascular events associated with SBP and DBP varied based on the specific cardiovascular event.
- A U-shaped association was observed between SBP and DBP and a composite outcome (all-cause mortality, MI, CHF, or stroke), all-cause mortality, MI, and CHF; but the lowest hazards differed for each outcome.
- For example, the lowest hazard ratio for all-cause mortality was associated with BPs of 140-155/70-80 mm Hg, for MI with 110-120/85-90 mm Hg, and for CHF with 125-135/70-75 mm Hg.
What are the specific effects of systolic blood pressure (SBP) and diastolic blood pressure (DBP) on various cardiovascular outcomes?
ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial) enrolled patients ≥55 years of age with hypertension and ≥1 other cardiovascular risk factor during 1994–2002; excluding patients with a history of heart failure, left ventricular ejection fraction <35%, or serum creatinine >2 mg/dl. Patients were randomized to receive chlorthalidone, amlodipine, or lisinopril with a target BP of <140/90 mm Hg; a fourth doxazosin arm was terminated early and excluded from this analysis. Publicly available ALLHAT data from the National Heart, Lung, and Blood Institute Biologic Specimen and Data Repository Information Coordinating Center (BioLINCC) were analyzed for simultaneous associations between repeated SBP and DBP measurements on a primary composite outcome of all-cause mortality, myocardial infarction (MI), congestive heart failure (CHF), or stroke; and on each individual outcome.
During a median follow-up of 4.4 years (interquartile range, 3.6-5.4 years), 33,357 participants experienced 2,636 MIs, 866 CHF events, 936 strokes, and 3,700 deaths; 8,138 patients (24.4%) had ≥1 event. For the composite outcome, all-cause mortality, MI, and CHF, a U-shaped association was observed with SBP and DBP, but the SBP and DBP associated with the lowest hazards differed for each outcome. For example, SBP/DBP of 140-155/70-80 mm Hg was associated with the lowest hazard ratio for all-cause mortality, compared with 110-120/85-90 mm Hg for MI and 125-135/70-75 mm Hg for CHF. In contrast, the association of SBP and stroke was linear.
The risk pattern of SBP and DBP differs by clinical outcomes. The authors suggest that individualization of BP targets may be appropriate in part depending on the cardiovascular event for which the patient is most at risk.
This study retrospectively re-analyzed observational data from ALLHAT, in which patients with hypertension and ≥1 additional cardiovascular risk factor were randomized to antihypertensive therapy with chlorthalidone, amlodipine, or lisinopril and a target BP <140/90 mm Hg. The study found that the optimal measured BP for cardiovascular risk reduction varied by the specific outcome—with a BP of 140-155/70-80 mm Hg associated with the lowest all-cause mortality, 110-120/85-90 mm Hg associated with the lowest risk of MI, and 125-135/70-75 mm Hg with the lowest risk for CHF. As a retrospective re-analysis of observational data, it is uncertain whether these findings reflect a causal relationship or a coincidental association between BP and outcomes. (The lowest risk for all-cause mortality associated with a BP range of 140-155/70-80 mm Hg is suspicious, and counter to current targets for BP control.) Although the study is thought provoking, any changes in the management of hypertension should await prospective reassessment of cardiovascular outcomes using current antihypertensive strategies.
Keywords: Amlodipine, Antihypertensive Agents, Blood Pressure, Chlorthalidone, Diastole, Heart Failure, Hypertension, Lipids, Lisinopril, Myocardial Infarction, Primary Prevention, Risk Factors, Stroke, Stroke Volume, Systole, Vascular Diseases
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