Prophylactic milrinone during OPCAB of posterior vessels: implication in angina patients taking beta-blockers

To determine whether a phosphodiesterase type 3 inhibitor can improve hemodynamics during off-pump coronary artery bypass grafting (OPCAB) of posterior vessels in patients on beta(1)-adrenoreceptor blockers.

Thirty patients scheduled for OPCAB of the obtuse marginal artery (OM), and taking atenolol 100 mg a day were randomized in a double-blind manner to receive either milrinone or placebo. Hemodynamic data were obtained after induction, before pericardial incision, during left anterior descending artery grafting, during OM grafting, and after removal of the stabilizer. During the OM grafting, dopamine was infused when the cardiac index (CI) decreased below 2.0 L/min/m(2), and phenylephrine was infused to maintain the arterial pressure with a CI above 2.0 L/min/m(2).

During OM anastomosis, there were significant differences in CI (milrinone [M] = +7.7%, control [C] = -13.7%, p=0.01), SVI (M=-21.5%, C=-35.8%, p=0.03), SvO(2) (M=-2.6%, C=-8.9%, p=0.02), and SVR (M=-28.1%, C=+1.1%, p=0.01) between the two groups, in terms of percentage change from baseline value. Dopamine was required more frequently and at a higher dose in the control group (M=13%, 5.0 microg/kg/min; C=67%, 10.1 microg/kg/min, p<0.05). Phenylephrine was infused in 33% of the patients in the milrinone group compared to 13% in the control group (p>0.05).

Prophylactic milrinone improves CI, SVI and SvO(2) reducing the need for high doses of dopamine during OM anastomosis in patients taking atenolol. Therefore, it can be used as an alternative to dopamine improving hemodynamics and organ perfusion during OPCAB of posterior vessels in patients on beta(1)-blockers.