Seven RCTs (n=1,448) were included in the review (the number of patients ranged from 104 to 400). The average angiographic follow-up time in the included studies varied from less than 21 days to 450 days.
Quality appraisal and study characteristics.
The number of participating surgeons varied (from 1 to 5) between studies, where reported. Analysis of the primary studies was by intention-to-treat in 6 trials. Intention-to graft with a pre- specified index was stated in 3 trials. Blind assessment of the outcome was stated in 5 trials. Graft method varied between studies. In most studies not all patients underwent angiography, which was used to evaluate graft patency.
Initial analysis of all included trials found that patients receiving off-pump coronary surgery had a lower graft patency than patients receiving conventional surgery; the relative risk (RR) was 0.959 (95% confidence interval, CI: 0.936, 0.983, p=0.001). Evidence of clinical and statistical heterogeneity was present (chi-squared test p<0.001; variation in RR attributable to heterogeneity using I-squared test, 78.4%). After examination of heterogeneity, 1 trial that used exclusive composite inflow grafting was excluded from further analyses of graft patency. The remaining 6 trials found that patients receiving off-pump coronary surgery had a lower graft patency than those undergoing conventional surgery (RR 0.953, 95% CI: 0.927, 0.980, p<0.001). There was no further evidence of heterogeneity (chi-squared test, p=0.374). Sensitivity analyses produced similar results.
Patients receiving off-pump coronary surgery received fewer grafts than those undergoing conventional coronary surgery; the standardised mean difference was -0.164 (95% CI: -0.286, -0.043, p=0.008) in the 6 trials. There was no evidence of statistical heterogeneity (I-squared 0%).