Heart rate reduction: a potential target for the treatment of myocardial ischaemia.

Because most of myocardial perfusion takes place during diastole, reducing the heart rate is likely to have anti-ischaemic effects. The present paper reviews the role of heart rate in relation to coronary artery disease outcome, as well as ways to reduce heart rate in the clinical setting. Nonpharmacological intervention, and particularly exercise training, has a definite effect on both heart rate reduction and the prevention of myocardial ischaemia. The protective role of beta-blockers after acute myocardial infarction is amply documented; their anti-ischaemic efficacy appears to be attributable to their effect on heart rate, but also to their role in cardiac inotropism. Recently, the If (funny) current inhibitor ivabradine, which has a potent heart rate reduction effect without any haemodynamic effect has demonstrated anti-ischaemic efficacy in a randomised trial versus placebo, as well as in trials where it showed an effect similar to that of the conventional anti-ischaemic agents amlodipine and atenolol. In addition, such an agent, which does not influence myocardial contractility, might be particularly valuable in the setting of myocardial stunning or acute left ventricular failure at the acute stage of myocardial infarction. However, only future studies will determine whether isolated heart rate reduction will have the same protective efficacy as that of beta-blocking agents in secondary prevention after myocardial infarction.