Background: In the context of complex aortic surgery, despite the wide consensus about the use of moderate hypothermia in association with antegrade selective cerebral perfusion (ASCP), its bilateral administration is not always warranted. The aim of the present meta-analysis was to investigate outcomes of unilateral versus bilateral ASCP.

Methods: Outcomes investigated were postoperative mortality and neurologic permanent and temporary disease (PND and TND); separate analysis of heterogeneity using the Cochrane Q statistic was used to perform comparisons. Circulatory arrest (CA) time and temperature, and sample size were explored as potential causes for heterogeneity with meta-regression analysis.

Results: The study population consisted of 3,723 patients receiving bilateral ASCP and 3,065 patients receiving unilateral ASC. Pooled analysis showed similar rates of postoperative mortality: 9.8% (95% confidence interval [CI], 7.8% to 12.3%) for bilateral ASCP versus 7.6% (95% CI, 5.7% to 10.2%) for unilateral ASCP; p = 0.19. Postoperative PND rates as well did not differ significantly: 6.9% (95% CI, 5.0% to 9.4%) for bilateral ASCP versus 5.8% (95% CI, 3.8% to 8.7%) for unilateral ASCP; p = 0.53. Similar results yielded from TND analysis: 9.3 % (95% CI, 7.0% to 12.2%) versus 6.5% (95% CI, 4.5% to 9.5%), respectively, p = 0.14. Meta-regression analysis showed that longer CA times were associated with significantly increased mortality only among patients administered with unilateral ASCP (model Q 65.8, p < 0.0001). Furthermore, higher CA temperatures were associated with significantly reduced rates of mortality (Q 64.1, p = 0.001), PND (Q 52.3, p = 0.01), and TND (Q 62.2, p = 0.002) in both groups.

Conclusions: Unilateral versus bilateral ASCP administration did not result in different mortality and neurologic morbidity rates. Nevertheless, among prolonged CA times unilateral ASCP resulted in poorer outcomes with respect to bilateral ASCP. Furthermore, moderate hypothermia was associated with best outcomes in both groups.