Off-pump versus on-pump coronary artery bypass grafting in acute coronary syndrome: a clinical analysis

Coronary artery bypass surgery for acute coronary syndrome: A network meta-analysis of on-pump cardioplegic arrest, off-pump, and on-pump beating heart strategies

BACKGROUND

Coronary artery bypass grafting (CABG) in the setting of an acute coronary syndrome is a high-risk procedure, and the best strategy for myocardial revascularisation remains debated. This study compares the 30-day mortality benefit of on-pump CABG (ONCAB), off-pump CABG (OPCAB), and on-pump beating heart CABG (OnBHCAB) strategies.

METHODS

A systematic search of three electronic databases was conducted for studies comparing ONCAB with OPCAB or OnBHCAB in patients with acute coronary syndrome (ACS). The primary outcome, 30-day mortality, was compared using a Bayesian hierarchical network meta-analysis (NMA). A random effects consistency model was applied, and direct and indirect comparisons were made to determine the relative effectiveness of each strategy on postoperative outcomes.

RESULTS

One randomised controlled trial and eighteen observational studies fulfilling the inclusion criteria were identified. A total of 4320, 5559, and 1962 patients underwent ONCAB, OPCAB, and OnBHCAB respectively. NMA showed that OPCAB had the highest probability of ranking as the most effective treatment in terms of 30-day mortality (odds ratio [OR], 0.50; 95% credible interval [CrI], 0.23-1.00), followed by OnBHCAB (OR, 0.62; 95% CrI, 0.20-1.57), however the 95% CrI crossed or included unity. A subgroup NMA of nine studies assessing only acute myocardial infarction (AMI) patients demonstrated a 72% reduction in likelihood of 30-day mortality after OPCAB (CrI, 0.07-0.83). No significant increase in rate of stroke, renal dysfunction or length of intensive care unit stay was found for either strategy.

CONCLUSIONS

Although no single best surgical revascularisation approach in ACS patients was identified, the significant mortality benefit with OPCAB seen with AMI suggests high acuity patients may benefit most from avoiding further myocardial injury associated with cardiopulmonary bypass and cardioplegic arrest.

Analysis of Risk Factors for Conversion from Off-Pump to On-Pump Coronary Artery Bypass Graft

BACKGROUND

Off-pump coronary artery bypass (OPCAB) is performed worldwide, but significant risks are associated with conversion to on-pump surgery. Therefore, we evaluated the composite outcomes between an OPCAB group and a conversion group.

METHODS

From January 2008 to December 2012, 100 consecutive patients underwent OPCAB at Hallym University Sacred Heart Hospital, of whom 84 underwent OPCAB without adverse events (OPCAB group), and 16 were converted to on-pump surgery (conversion group). Early morbidity, early and long-term mortality, and major adverse cardiac and cerebrovascular events (MACCEs) were the primary and long-term composite endpoints.

RESULTS

The mean follow-up period was 55±26 months, with 93% of the patients completing follow-up. The composite outcomes in the OPCAB and conversion groups were as follows: early morbidity, 2.3% versus 12.5%; early mortality, 4.7% versus 0%; long-term mortality, 14.3% versus 25.0%; and MACCEs, 14.3% versus 18.8%, respectively. No composite endpoints showed statistically significant differences. Preoperative acute myocardial infarction (AMI) was identified as an independent risk factor for conversion (p=0.025).

CONCLUSION

The conversion group showed no statistically significant differences in early mortality and morbidity, MACCEs, or long-term mortality compared with the OPCAB group. The preoperative diagnosis of AMI was associated with an increased number of conversions to on-pump surgery.

Optimal coronary artery bypass grafting strategy for acute coronary syndrome

OBJECTIVE

Conventional coronary artery bypass grafting (CABG) using cardiopulmonary bypass and cardiac arrest is associated with higher mortality and morbidity rates in acute coronary syndrome (ACS) patients undergoing surgery. Although off-pump CABG (OPCAB) is beneficial for high-risk patients, its efficacy for ACS is unknown, with on-pump beating CABG an adjunctive method. We investigated the effects of OPCAB and on-pump beating CABG for ACS.

METHODS

We evaluated 121 consecutive patients with ACS (91 males, 30 females; mean age 69.5 ± 10.3 years) who underwent CABG since 2000. Seventy-five had unstable angina (UA) and 46 acute myocardial infarction (AMI) [non-ST elevation (NSTEMI): 22, ST elevation (STEMI): 24]. We assessed CABG for acute coronary syndrome under our primary OPCAB strategy, and compared perioperative status between UA and AMI patients.

RESULTS

(1) Sixty-five (87 %) with UA underwent OPCAB, 8 on-pump beating CABG, and 2 conventional CABG. Conversion from OPCAB was seen in 4 patients. In-hospital mortality was 1.3 %. (2) All UA patients who had intra-aortic balloon pumping (IABP) underwent OPCAB. No patients with preoperative IABP experienced conversion from OPCAB. (3) In AMI patients, hospital mortality was higher (8.9 %) and the ratios for OPCAB, on-pump beating CABG, and conventional CABG were 39, 57, and 4 %, respectively. Mortality was exclusively seen in patients with STEMI who underwent conventional CABG.

CONCLUSIONS

OPCAB might have beneficial effects for ACS patients with UA, while IABP was found essential for completing OPCAB. In AMI patients, on-pump beating CABG might be reasonable for avoiding conversion from OPCAB and ischemic perfusion injury.

Should we consider off-pump coronary artery bypass grafting in patients with acute coronary syndrome?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether off-pump coronary artery bypass (OPCAB) grafting should be considered as an alternative to the conventional on-pump surgery (ONCAB) in patients presenting with acute coronary syndrome (ACS) requiring emergency revascularization. Eighty-two papers were identified by a systematic search, of which nine were judged to best answer the clinical question. Of these, one was a randomized controlled trial and the remaining eight were retrospective observational studies. The author, journal, date, patient group, country of publication, relevant outcomes, results and study weaknesses were tabulated. In total, these nine studies included 3001 patients (n = 817 OPCAB, 2184 ONCAB) undergoing emergency revascularization in the setting of ACS. The timing between the onset of ACS and operative intervention ranged from 6 to 72 h. All cases were categorized as urgent/emergent according to the National confidential enquiry into patient outcome and death classification of intervention. Six studies included patients with preoperative cardiogenic shock; however the majority of patients were haemodynamically stable at the time of surgery. Three out of nine studies showed an improvement in 30-day mortality with OPCAB although the remaining six reveal no significant mortality benefit. No difference in long-term mortality was observed between the two techniques. OPCAB was associated with significantly fewer grafts per patient (six studies) and less complete revascularization (two studies). We conclude that whilst OPCAB may have a beneficial effect on 30-day mortality in haemodynamically stable patients undergoing emergency revascularization, there is a lack of high-quality data with clearly defined patient demographics. Future studies must ensure adequate preoperative matching between OPCAB and ONCAB groups and clearly categorize haemodynamic status, disease pattern and time to surgery in order to determine the patients in whom OPCAB may confer the greatest benefit.