Temporary biventricular pacing improves bypass graft flows in coronary artery bypass graft patients with permanent atrial fibrillation

OBJECTIVES: We have previously demonstrated the impact of univentricular pacing modalities on bypass graft flow (BGF) in the coronary artery bypass graft (CABG) patient with permanent atrial fibrillation (AF). The aim of the present study was to determine the mechanism of this improved coronary conduit and, in addition, to explore the possible benefits with biventricular pacing in patients with and without severe left ventricular dysfunction. METHODS: In 43 CABG patients [mean age 69.5 ± 1.3 years; ejection fraction (EF) 49 ± 2%] with AF, we analysed coronary vascular resistances (CVRs) and the contemporary changes in the BGF obtained during right ventricular outflow tract (RVOT), right- (RV), left- (LV) and right-left ventricular pacing (biventricular pacing, BiVP) using the ultrasonic transit-time methodology. RESULTS: BiVP resulted in the highest percentage decrease of CVR in the overall study group by 17.5 ± 3.0% (P < 0.001), followed by RVOT pacing with 13.9 ± 3.9%. Accordingly, the highest mean BGF was achieved during BiVP, resulting in a 21.6 ± 2.6% increase when compared with no pacing and 16 ± 3.7% when compared with RV pacing. Analysis of patients according to their preoperative LV function (EF ≥50%, n = 26; EF <50%, n = 17) showed significantly lower CVR (P < 0.037) and higher BGF during BiVP in patients with lower EF. CONCLUSIONS: Placement of an additional LV pacing wire offered a significant improvement in BGF by minimizing CVR in patients with AF and poor EF.