Background and objectives: Relative effectiveness of blood pressure (BP)-lowering treatment on various outcomes was evaluated by meta-analyses restricted to randomized controlled trials (RCTs) measuring all major outcomes, and the question whether BP lowering and each class of antihypertensive agents prevent new-onset heart failure by meta-analyses limited to RCTs excluding baseline heart failure from randomization.
Methods: Source of these meta-analyses are our databases of BP-lowering RCTs vs placebo or less-active treatment, and head-to-head comparisons of different antihypertensive classes. Risk ratios (RRs) and 95% confidence intervals of seven outcomes were calculated by a random-effects model. The relationships of outcome reductions to BP differences were investigated by meta-regressions.
Results: First, 35 BP-lowering RCTs measured all outcomes, and heart failure [RR 0.63 (0.52-0.75)] and stroke [RR 0.58 (0.49-0.68)] were the outcomes most effectively prevented. Second, heart failure and stroke reductions were significantly related to SBP, DBP and pulse pressure reductions. Third, in 18 BP-lowering RCTs excluding baseline heart failure from recruitment, heart failure reduction ('new-onset' heart failure) [RR 0.58 (0.44-0.75)] was very similar to that in the entire set of RCTs. Fourth, in meta-analyses of head-to-head comparisons of different antihypertensive classes, calcium antagonists were inferior in preventing 'new-onset' heart failure [RR 1.16 (1.01-1.33)]. However, this inferiority disappeared when meta-analysis was limited to RCTs allowing concomitant use of diuretics, β-blockers or renin-angiotensin system blockers also in the calcium antagonist group [RR 0.96 (0.81-1.12)].
Conclusion: BP-lowering treatment effectively prevents 'new onset' heart failure. It is suggested that BP lowering by calcium antagonists is effective as BP lowering by other drugs in preventing 'new-onset' heart failure, unless the trial design creates an unbalance against calcium antagonists.