Effect of preoperative ivabradine on hemodynamics during elective off-pump CABG

Ivabradine is a specific heart rate (HR)-lowering agent which blocks the cardiac pacemaker I_f channels. It reduces the HR without causing a negative inotropic or lusitropic effect, thus preserving ventricular contractility. The authors hypothesized that its usefulness in lowering HR can be utilized in patients undergoing off-pump coronary artery bypass (OPCAB) surgery.

To study the effects of preoperative ivabradine on hemodynamics (during surgery) in patients undergoing elective OPCAB surgery.

Fifty patients, New York Heart Association (NYHA) class I and II, were randomized into group I (control, n = 25) and group II (ivabradine group, n = 25). In group I, patients received the usual anti-anginal medications in the preoperative period, as per the institutional protocol. In group II, patients received ivabradine 5 mg twice daily for 3 days before surgery, in addition to the usual anti-anginal medications. Anesthesia was induced with fentanyl, thiopentone sodium, and pancuronium bromide as a muscle relaxant and maintained with fentanyl, midazolam, pancuronium bromide, and isoflurane. The hemodynamic parameters [HR and mean arterial pressure (MAP)] and pulmonary artery (PA) catheter-derived data were recorded at the baseline (before induction), 3 min after the induction of anesthesia at 1 min and 3 min after intubation and at 5 min and 30 min after protamine administration. Intraoperatively, hemodynamic data (HR and MAP) were recorded every 10 min, except during distal anastomosis of the coronary arteries when it was recorded every 5 min. Post-operatively, at 24 hours, the levels of troponin T and brain natriuretic peptide (BNP) were measured. This trial's CTRI registration number is CTRI/005858.

The HR in group II was lower when compared to group I (range 59.6-72.4 beats/min and 65.8-80.2 beats/min, respectively) throughout the study period. MAP was comparable [range (78.5-87.8 mm Hg) vs. (78.9-88.5 mm Hg) in group II vs. group I, respectively] throughout the study period. Intraoperatively, 5 patients received metoprolol in group I to control the HR, whereas none of the patients in group II required metoprolol. The incidence of preoperative bradycardia (HR <60 beats/min) was higher in group II (20%) vs. group I (8%). There was no difference in both the groups in terms of troponin T and BNP level after 24 hours, time to extubation, requirement of inotropes, incidence of arrhythmias, in-hospital morbidity, and 30-day mortality.

Ivabradine can be safely used along with other anti-anginal agents during the preoperative period in patients undergoing OPCAB surgery. It helps to maintain a lower HR during surgery and reduces the need for beta-blockers in the intraoperative period, a desirable and beneficial effect in situations where the use of beta-blockers may be potentially harmful. Further studies are needed to evaluate the beneficial effects of perioperative Ivabradine in patients with moderate-to-severe left ventricular dysfunction.