Clinical effect of 'pure' heart rate slowing with a prototype If current inhibitor: placebo-controlled experience with ivabradine.

Heart rate slowing is generally accepted as effective for angina prevention but this approach has not been rigorously evaluated as no pure heart rate slowing treatment has been available. With the identification of the I(f) current, the primary modulator of heart rate, and use of this as a target for drug development, the role of isolated heart rate slowing can be elucidated. More than 4,000 patients now have been studied in angina prevention trials with ivabradine, a prototype I(f) current inhibitor devoid of other cardiovascular effects. These studies demonstrate the efficacy of isolated heart rate slowing for angina prevention. Indeed, in one direct comparison with atenolol involving 939 patients, ivabradine not only was non inferior to the Beta-blocker but nominally appeared to be more efficient in angina prevention. Moreover, since ivabradine is devoid of most of the adverse effects of beta-blockers (and of calcium channel blockers), it is a suitable alternative when these established drugs are not adequately tolerated. Additional studies now must assess other potential actions in patients with coronary disease.