Efficacy of ivabradine, a new selective I(f) inhibitor, compared with atenolol in patients with chronic stable angina

Aims: Ivabradine, a new I(f) inhibitor which acts specifically on the pacemaker activity of the sinoatrial node, is a pure heart rate lowering agent. Ivabradine has shown anti-ischaemic and anti-anginal activity in a placebo-controlled trial. The objective of this study was to compare the anti-anginal and anti-ischaemic effects of ivabradine and the beta-blocker atenolol.

Methods and results: In a double-blinded trial, 939 patients with stable angina were randomized to receive ivabradine 5 mg bid for 4 weeks and then either 7.5 or 10 mg bid for 12 weeks or atenolol 50 mg od for 4 weeks and then 100 mg od for 12 weeks. Patients underwent treadmill exercise tests at randomization (M(0)) and after 4 (M(1)) and 16 (M(4)) weeks of therapy. Increases in total exercise duration (TED) at trough at M(4) were 86.8+/-129.0 and 91.7+/-118.8 s with ivabradine 7.5 and 10 mg, respectively and 78.8+/-133.4 s with atenolol 100 mg. Mean differences (SE) when compared with atenolol 100 mg were 10.3 (9.4) and 15.7 (9.5) s in favour of ivabradine 7.5 and 10 mg (P<0.001 for non-inferiority). TED at M(1) improved by 64.2+/-104.0 s with ivabradine 5 mg and by 60.0+/-114.4 s with atenolol 50 mg (P<0.001 for non-inferiority). Non-inferiority of ivabradine was shown at all doses and for all criteria. The number of angina attacks was decreased by two-thirds with both ivabradine and atenolol.

Conclusion: Ivabradine is as effective as atenolol in patients with stable angina.