[New pharmacological approaches to ischemic heart disease]

Major steps have been made in the treatment of ischemic heart disease from the discovery of nitrates as antianginal medication to the techniques of percutaneous angioplasty. This incredible therapeutic progress has resulted in a reduced incidence of ischemic heart disease and related mortality and morbidity. However, statistical and epidemiological data indicate that in ischemic heart disease, despite the achievement of great success, there is a necessity for a further step toward treatment, considering the fact that the characteristics of this population are changing (increased prevalence of subendocardial infarction compared with classic transmural infarction, especially in the elderly population). Furthermore, the need for alternative therapeutic approaches to traditional ones is recognized. Ranolazine is a selective inhibitor of Na channels that prevents pathological extension of late Na current developing in the ischemic myocardial cell. This current is responsible for calcium overload, with consequent impairment of diastolic relaxation. Ranolazine reduces Na overload induced by calcium and improves diastolic relaxation and coronary subendocardial flow, without affecting hemodynamic parameters such as blood pressure, heart rate, or inotropic state of the heart, avoiding undesirable side effects. Efficacy of ranolazine has been evaluated in several trials, using clinical and instrumental endpoints (MARISA and CARISA) or, more recently, using endpoints such as mortality and reinfarction (ERICA and MERLIN-TIMI 36). Ivabradine acts through the inhibition of late Na current (also known as If), which controls the spontaneous diastolic depolarization of sinus node cells. The partial inhibition of these channels reduces the frequency of sinus node action potential initiation, resulting in decreased heart rate without effects on contractility, atrio-ventricular conduction, or repolarization. The BEAUTIFUL trial has tested whether the effect of ivabradine in lowering heart rate is able to reduce mortality and cardiovascular morbidity in patients with coronary artery disease and left ventricular systolic dysfunction. The most significant results were obtained in the subgroup of patients with life-limiting exertional angina. In this group, ivabradine significantly reduced the primary endpoint, a composite of cardiovascular death, hospitalization for fatal and nonfatal acute myocardial infarction (AMI) or heart failure, by 24%, and hospitalizations for AMI by 42%. In the subgroup of patients with baseline heart rate >70 bpm, hospitalizations for AMI and revascularization were reduced by 73% and 59%, respectively.