Comparative effectiveness of metoprolol, ivabradine, and its combination in the management of inappropriate sinus tachycardia in coronary artery bypass graft patients

BACKGROUND: Inappropriate sinus tachycardia (IST) is an arrhythmic complication observed after coronary artery bypass graft (CABG) surgery which left untreated, commonly increases chances of postoperative stroke. The primary study objective was comparing effectiveness of beta blocker-metoprolol; a specific I(f) blocker-ivabradine and its combination in patients who develop IST as a complication following CABG. MATERIALS AND METHODS: An open-labeled, investigator initiated, clinical study was conducted on 150 patients who developed IST (heart rate [HR] >100 beats/min) following elective CABG surgery. The patients were randomized into three treatment groups. Group I – received ivabradine (5 mg), Group II – metoprolol (25 mg), and Group III – ivabradine (5 mg) and metoprolol (25 mg). Treatment was given orally, twice a day for 7 days in all the three groups postoperatively. Primary endpoints were comparative effectiveness in HR and blood pressure reduction following treatment. RESULTS: IST was diagnosed by an electrocardiogram (12-lead) considering morphological features of P-wave and with 32% increase from baseline HR in all the three groups. Compared to IST arrthymic rate, HR was reduced in all groups following respective treatment (P = 0.05). Reduction in HR was significant (P < 0.05) in combination group followed by ivabradine which was significantly greater than metoprolol treated group. None of the treatments clinically changed the systolic, diastolic and mean blood pressure till discharge. No surgery/treatment-related complications were observed in any groups. CONCLUSION: Ivabradine stands as a pharmacological option for controlling HR and rhythm without associated side effects in postoperative CABG patients with IST.