In patients with hypertension and coronary artery disease, a J-curve was evident for the relation between BP and adverse outcomes, but the relation was attenuated after adjustment for baseline factors.
Given that coronary blood flow occurs during diastole, hypertensive people with coronary artery disease (CAD) might be more sensitive than those without CAD to diastolic blood pressure reductions. In a secondary analysis of data from an earlier study (Journal Watch Dec 23 2003), researchers evaluated the relation between BP and cardiovascular outcomes among 22,576 patients with CAD and hypertension who were treated with atenolol or sustained-release verapamil.
At baseline, patients with lower diastolic BP (DBP) were older and had higher rates of previous myocardial infarction, heart failure, and diabetes than those with higher DBP. After a median follow-up of 2.7 years, a J-shaped curve — with worse outcomes both above and below an optimal BP — was evident for the relation between both systolic BP (SBP) and DBP and for the primary outcome of all-cause mortality, nonfatal MI, or nonfatal stroke; the optimal BP was 119/84 mm Hg. After adjustment for baseline characteristics, the relation between SBP and outcome failed to show evidence of a substantial J-curve; for DBP, the J-curve was drastically attenuated, and the nadir moved to 74 mm Hg.
Comment: In a recent study, middle-aged men with optimal BP (SBP <120, DBP <80) were found to have lower risk for cardiovascular events than were those with high-normal BP (Journal Watch Feb 21 2006). The current study suggests that, among people with hypertension and CAD, lower is not necessarily better. Although adjustment for baseline risk significantly attenuated the J-curve, the relation persisted for DBP. Of note, in this observational study, researchers were unable to address whether the observed J-curve was the result of BP reduction or of underlying illness.
— Jamaluddin Moloo, MD, MPH
Citation(s):
Messerli FH et al. Dogma disputed: Can aggressively lowering blood pressure in hypertensive patients with coronary artery disease be dangerous? Ann Intern Med 2006 Jun 20; 144:884-93.