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The Relation Between Surgeon Volume and Outcome Following Off-Pump vs On-Pump Coronary Artery Bypass Graft Surgery

Results of On-Pump Versus Off-Pump Coronary Artery Bypass Grafting

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A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was, in [patients undergoing off-pump CABG] are [postoperative mortality and morbidity outcomes] acceptable when performed by [trainees]? Altogether more than 597 papers were found using the reported search, of which 8 represented the best evidence to answer the clinical question. Six retrospective cohort studies directly compared the performance of trainees and experienced surgeons in off-pump coronary artery bypass graft surgery. Of the remaining papers, one recorded the performance of trainees in on- and off-pump operations and finally one paper evaluated a single trainee's performance in off-pump coronary artery bypass graft surgery, both supervised and unsupervised, over a 1-year period. It is important to note that the two respective cohort studies included in our analysis compared similar cohorts of patients. However, both studies were included in our paper as they provide additional information regarding trainee performance. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Although a heterogeneous range of postoperative complications were recorded in the identified studies, we were able to determine that, overall, there was no significant difference in the 30-day mortality seen in operations performed by trainees or experienced surgeons. The incidence of myocardial infarction and stroke were also similar among cases performed by both groups. However, senior surgeons were more likely to operate on patients with more complex or severe disease, or those requiring more urgent operations. Therefore, it was not possible to directly compare outcomes between trainees and experienced surgeons in operations of similar complexity. However, we conclude that despite the absence of randomized controlled trials comparing the performance of trainees and experienced surgeons in off-pump coronary artery bypass (OPCAB) surgery, the evidence provided in this paper supports the involvement of trainees in performing off-pump coronary artery bypass graft surgery as a reliable and safe alternative to on-pump coronary artery bypass graft surgery in selected cases.

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Most recent published meta-analysis of randomized controlled trials (RCTs) showed that off-pump coronary artery bypass graft surgery (CABG) reduces incidence of stroke by 30% compared with on-pump CABG, but showed no difference in other outcomes. New RCTs were published, indicating need of new meta-analysis to investigate pooled results adding these further studies. MEDLINE, EMBASE, CENTRAL/CCTR, SciELO, LILACS, Google Scholar and reference lists of relevant articles were searched for RCTs that compared outcomes (30-day mortality for all-cause, myocardial infarction or stroke) between off-pump versus on-pump CABG until May 2012. The principal summary measures were relative risk (RR) with 95% Confidence Interval (CI) and P values (considered statistically significant when <0.05). The RR's were combined across studies using DerSimonian-Laird random effects weighted model. Meta-analysis and meta-regression were completed using the software Comprehensive Meta-Analysis version 2 (Biostat Inc., Englewood, New Jersey, USA). Forty-seven RCTs were identified and included 13,524 patients (6,758 for off-pump and 6,766 for on-pump CABG). There was no significant difference between off-pump and on-pump CABG groups in RR for 30-day mortality or myocardial infarction, but there was difference about stroke in favor to off-pump CABG (RR 0.793, 95% CI 0.660-0.920, P=0.049). It was observed no important heterogeneity of effects about any outcome, but it was observed publication bias about outcome "stroke". Meta-regression did not demonstrate influence of female gender, number of grafts or age in outcomes. Off-pump CABG reduces the incidence of post-operative stroke by 20.7% and has no substantial effect on mortality or myocardial infarction in comparison to on-pump CABG. Patient gender, number of grafts performed and age do not seem to explain the effect of off-pump CABG on mortality, myocardial infarction or stroke, respectively.

Commentary: Does a “less is more” approach reduce delirium in patients undergoing coronary artery bypass grafting?

It has been suggested that off-pump coronary artery bypass grafting (CABG) surgery reduces myocardial ischemia-reperfusion injury, postoperative systemic inflammatory response, and oxidative stress. The aim of this study was to measure serum malondialdehyde (MDA), high-sensitivity C-reactive protein (hs-CRP), M30, and M65 levels and to investigate the relationship between M30 levels and oxidative stress and inflammation in patients undergoing on-and off-pump CABG surgery. Fifty patients were randomly assigned to on-pump or off-pump CABG surgery (25 patients off-pump and 25 on-pump CABG surgery), and blood samples were collected prior to surgery, and 30 minutes, 60 minutes, 6 hours, and 24 hours after CABG surgery. Compared to the on-pump group, serum MDA levels at 30 minutes, 60 minutes, 6 hours, and 24 hours after the CABG surgery were significantly lower in the off-pump group (P=.001, P=.001, P=.001, and P=.001, respectively). Serum M30 levels were found to be elevated in both groups, returning to baseline at 24 hours. When compared to baseline, the hs-CRP level reached its peak at 24 hours at 13.28±5.32 mg/dL in the on-pump group, and 15.44±4.02 mg/dL in the off-pump group. CABG surgery is associated with an increase in inflammatory markers and serum M30 levels, indicating epithelial/endothelial apoptosis in the early period.

Outcomes of On-Pump versus Off-Pump Coronary Artery Bypass Graft Surgery in the High Risk (AusSCORE > 5)

Background: The reply of question of “which coronary artery bypass grafting (CABG) technique is superior in elderly patients, off-pump or on-pump CABG surgery?” is controversial. We aimed to compare the early clinical outcomes in elderly patients undergoing off-pump and on-pump CABG. Methods: From January 2009 to January 2015, 344 elderly patients (aged 70 or older) underwent off-pump (n = 137) or on-pump (n = 207) CABG. Patients’ medical records were retrospectively reviewed, and their baseline preoperative characteristics, operative data and postoperative outcomes were analyzed, thereby a comparison of early outcomes between off-pump and on-pump patients was performed. Results: Mean age of patients was 74.4 ± 3.8 years. Both groups were statistically similar in terms of baseline preoperative characteristics. Number of distal bypass was significantly lower in off-pump group than in on-pump group. Postoperative length of intensive care unit and hospital stay were similar between two groups. Amounts of transfused blood products were significantly lower in off-pump CABG group. There were no significant differences in terms of postoperative complications and mortality between two groups. Conclusions: Our results did not reveal a significant benefit of either surgical technique with respect to early-term clinical outcomes in elderly CABG patients. Further investigations are needed to determine whether off-pump CABG is superior than on-pump CABG in elderly patients.

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