Adverse clinical consequences associated with conventional coronary artery bypass (CCAB) surgery have largely been attributed to cardiopulmonary bypass circuit (CPB), hypothermic cardiac arrest, aortic cannulation and cross-clamping.
Consequently, there has been a growing interest in safer alternatives to CCAB, including off-pump beating heart bypass surgery (OPCAB, see Figure 1). Since the introduction of OPCAB for coronary artery disease, numerous studies have been published to evaluate the impact of OPCAB surgery compared with CCAB. However, subsequent prospective randomised studies and meta-analyses comparing OPCAB and CCAB surgery were performed on low-risk patients or mixed-risk populations. Due to underpowered design for infrequent complications, they usually failed to demonstrate a significant benefit of OPCAB surgery on early mortality and peri-operative major cardiac and cerebrovascular events. In recent years, further efforts have been made to elucidate the meaning of beating-heart concepts for patients with specific extra-cardiac and cardiac risk factors for extracorporeal circulation and cardioplegic arrest. In this article current study evidence on varying subsets of patients is summarised.
Patients with Specific Extra-cardiac Morbidity
In a meta-analysis including seven non-randomised studies and 1,672 patients with advanced age (mostly >80 years of age), 30-day mortality was 4.1% for OPCAB surgery compared with 5.6% for CCAB, without reaching statistical significance.1 However, in this analysis a significant reduction of peri-operative stroke rate (6.6% versus 1.0%), blood transfusion requirement (76.6% versus 47.8%), post-operative new onset of atrial fibrillation (45.9% versus 30.4%) and peri-operative intra-aortic balloon pump insertion (9.5% versus 1.5%) was demonstrated for the OPCAB approach.
No early survival benefit could be found in three retrospective, risk-adjusted studies when using OPCAB in diabetic patients.2-4 In two of these studies the peri-operative stroke rate was significantly reduced. This was also shown by Puskas and co-workers in their meta-analysis on 2,478 diabetic patients, finding a stroke rate of 1.0% for OPCAB and 2.1% for CCAB surgery.1 In this meta-analysis post-operative atrial fibrillation was also reduced for OPCAB. In a propensity score-adjusted analysis on diabetic patients, Magee also found a significant lower rate of blood transfusion requirement and post-operative new onset of renal replacement therapy.3
In a retrospective analysis of 16,871 female patients from 78 cardiac surgery units in North America, Brown and colleagues quoted a reduced peri-operative mortality of 3.1% for OPCAB compared with 3.9% for CCAB surgery. In a risk-adjusted mortality analysis they found a 42% increase in mortality for CCAB operation, however, without finding other significant differences in peri-operative complications.5 Similar to these results, in a propensity score-matched study of 7,932 women, CCAB surgery was associated with a 73% increase in operative mortality and a 47% increased risk of post-operative bleeding.6
Chronic Obstructive Pulmonary Disease
Three randomised and non-randomised studies on a limited number of patients (n=37-76) with pre-operative chronic obstructive pulmonary disease (COPD) are now available. All of them demonstrate a trend towards reduced ventilation time and lower pulmonary complications when using OPCAB strategies.7-9 In a meta-analysis of these studies, no significant benefit on peri-operative mortality and severe morbidity was evident. However, pulmonary complications were 12.5% in the CCAB patients and thus more frequent than in the OPCAB patients, where no pulmonary complications were recognised.1/>/>/>/>/>/>/>/>/>/>/>/>/>/>
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