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 If 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