Background and objective: Whether blood pressure (BP) reduction is a necessary prerequisite for cardiovascular risk reduction or an epiphenomenon has not been definitively established. We used an innovative analytic method to address this question.
Methods: For 7,287 participants in a stable angina trial comparing long-acting nifedipine to placebo, we estimated the BP response after 2 weeks of treatment corrected for regression-to-the mean, and then related the latter and assigned treatment to subsequent cardiovascular outcomes.
Results: Subsequent stroke and heart failure was strongly related to 2-week corrected systolic BP response, but coronary angiography and bypass surgery was not. Adjustment for the 2-week corrected systolic BP response changed nifedipine effect estimates (relative to placebo) for subsequent stroke from 28% (P=0.04) to 21% (P=0.13) risk reduction, and for heart failure from 30% (P=0.02) to 21% (P=0.11) risk reduction; but did not alter the effect estimates for coronary angiography (27% reduction, P<0.001), and coronary bypass surgery (22% reduction, P=0.002).
Conclusion: The stroke and heart failure risk reduction by nifedipine GITS in patients with stable angina can be attributed partly to its BP lowering effect, whereas effects on coronary procedures are likely to be related almost entirely to its antianginal effects.