Comparison of ivabradine versus metoprolol in early phases of reperfused anterior myocardial infarction with impaired left ventricular function: preliminary findings.

BACKGROUND: beta-blockers in ST-segment elevation myocardial infarction (STEMI) are indicated for patients without a contraindication, particularly in patients with high heart rates (HR) or blood pressures. Epidemiological studies have shown that elevated HR represents a risk factor for cardiovascular morbidity. The study investigates the feasibility, tolerability, and the effects after 30 days of follow-up of ivabradine (IVA) versus metoprolol (METO) in early phases of anterior STEMI reperfused by percutaneous coronary intervention (PCI).

METHODS AND RESULTS: Patients with a first anterior STEMI, Killip class I-II, an acceptable echocardiographic window, and admitted within 4hours of the onset of symptoms, with an ejection fraction <50%. METO or IVA, 12hours after PCI (double blind), were administered twice per day. Blood pressure (BP), heart rate (HR), electrocardiogram (ECG), and laboratory parameters were monitored during the study. At entry, day 10, day 30, and day 60, by echocardiography, the ESV, EDV, E/A ratio, E wave deceleration time, isovolumetric relaxation time were measured. A total of 155 (50 females, 105 males) patients were randomized in 2 groups: a group received METO (76 patients) 12hours after PCI and a group received IVA (79 patients) 12hours after PCI. The 2 groups were similar for clinical characteristics. No difference was evidenced in HR, systolic blood pressure, diastolic blood pressure, age (range, 39-73 years), sex, ejection fraction (EF), creatine kinase peak, between the 2 groups at entry. Both groups were similar for time to angiography and interventional procedures and number of vessels diseased. IVA group: the 79 patients showed 2 side effects and 5 readmissions: 4 for ischemic events and 1 for heart failure, and 1 sudden death; METO group: the 76 patients had 4 ischemic events, 2 side effects, and 1 patient died during re-acute MI (intrastent thrombosis) and 8 readmissions for heart failure signs. The systolic blood pressure and diastolic blood pressure showed a significant reduction in both groups, P < .0001, respectively), and significant lower values were observed in METO group, P=.0001). The HR was significantly reduced in both groups, P < .0001). IVA group showed a significant increase in EF, P=.0001, with concomitant reduction in ESV and EDV (P=.0001, and .048, respectively). The diastolic parameters were similar in both groups during study period.

CONCLUSIONS: Our results suggest that ivabradine may be administered early (12hours after PCI) to patients with successful PCI for anterior STEMI with an impaired left ventricular function and high HR and sinus rhythm. A larger sample of patients and further studies are required to evaluate the effects of ivabradine on clinical end points.