Comparison of perfusion and thickening between vein and right internal thoracic artery composite grafts from a randomized trial substudy

Abstract

Background: Improvements in myocardial perfusion and thickening were compared in coronary artery bypass grafting patients who received saphenous vein (SV) Y-composite grafts versus those who received right internal thoracic artery ([R]ITA) Y-composite grafts.

Methods: Of the 224 patients enrolled in a randomized clinical trial, 116 patients (SV group, n = 65; RITA group, n = 51) in whom myocardial single-photon-emission computed tomography was performed preoperatively, and at 3 months and 1 year postoperatively, were retrospectively studied. A 20-segment model was adopted, and a total of 792 ischemic myocardial segments (SV group, n = 443; RITA group, n = 349) were analyzed. The reversibility score (rest minus stress perfusion value) as an indicator of ischemic myocardium, and Z-values for segmental myocardial thickening, were calculated.

Results: Compared with preoperative values, both myocardial perfusion and segmental myocardial thickening had improved significantly at 3 months and 1 year postoperatively (reversibility scores [mean ± SD] were, respectively: 13.5 ± 8.0 vs 5.8 ± 6.2 and 5.1 ± 6.2, P < .001; Z-values were -1.13 ± 1.53 vs -0.62 ± 1.40 and -0.67 ± 1.35, P < .001). Mixed-effect model analyses showed no differences in improvements in myocardial perfusion and segmental myocardial thickening between the 2 groups 1 year after revascularization. Separate analysis demonstrated less improvement of myocardial perfusion in the right coronary artery territory of the RITA group than the SV group, with marginal significance (P = .056).

Conclusions: Improvements in myocardial perfusion and segmental myocardial thickening were similar between the 2 groups at 1 year after revascularization. The SV, versus the right ITA, composite graft may be more beneficial in perfusion improvement of the right coronary artery territory.

Keywords: myocardial SPECT; off-pump CABG; saphenous vein.