Transthoracic clamp versus endoaortic balloon occlusion in minimally invasive mitral valve surgery: a systematic review and meta-analysis

: This systematic review and meta-analysis aims to determine outcomes following aortic occlusion with the transthoracic clamp (TTC) versus endoaortic balloon occlusion (EABO) in patients undergoing minimally invasive mitral valve surgery. A subgroup analysis compares TTC to EABO with femoral cannulation separately from EABO with aortic cannulation. We searched Medline and Embase up to December 2018. Two people independently and in duplicate screened title and abstracts, full-text reports, extracted data and assessed the risk of bias using the Cochrane risk-of-bias tool for non-randomized studies. We identified 1564 reports from which 11 observational studies with 4181 participants met the inclusion criteria. We found no evidence of difference in the risk of postoperative death or cerebrovascular accident (CVA) between the 2 techniques. Evidence for a reduction in aortic dissection with TTC was found: 4 of 1590 for the TTC group vs 19 of 2492 for the EABO group [risk ratio 0.33, 95% confidence interval (CI) 0.12-0.93; P = 0.04]. There was no difference in aortic cross-clamp (AoX) time between TTC and EABO [mean difference (MD) -5.17 min, 95% CI -12.40 to 2.06; P = 0.16]. TTC was associated with a shorter AoX time compared to EABO with femoral cannulation (MD -9.26 min, 95% CI -17.00 to -1.52; P = 0.02). EABO with aortic cannulation was associated with a shorter AoX time compared to TTC (MD 7.77 min, 95% CI 3.29-12.26; P < 0.001). There was no difference in cardiopulmonary bypass (CPB) time between TTC and EABO with aortic cannulation (MD -4.98 min, 95% CI -14.41 to 4.45; P = 0.3). TTC was associated with a shorter CPB time compared to EABO with femoral cannulation (MD -10.08 min, 95% CI -19.93 to -0.22; P = 0.05). Despite a higher risk of aortic dissection with EABO, the rates of survival and cerebrovascular accident across the 2 techniques are similar in minimally invasive mitral valve surgery.