Commentary on ‘ABO Blood Type does not Influence the Risk of Cardiovascular Complications and Mortality After Vascular Surgery’

Abstract

During the past four decades, ABO blood types has been proposed as one of the prognostication factors of cardiovascular disease and non-O blood groups have been identified as a risk factor for coronary artery disease and associated mortality. A similar trend has been described for development of cardiovascular complications in the postoperative period. These interesting observations have been attributed to elevated levels of vonWillebrand factor in individuals with non-O blood groups, which plays a critical role in subendothelial adhesion of platelets, a process that is considered an initial step in acute clot formation and atherogenesis, especially under high shear stress conditions. In this issue of European Journal of Vascular and Endovascular Surgery, Bakker and colleagues present a retrospective review of 4679 patients undergoing vascular surgery from 1990 through 2011. Cardiac complications occurred in 4.9% of non-O blood type and 5.5% of O blood group patients (P 1⁄4 0.42) within 30 days after surgery, and there was no significant difference in mortality during a median follow up of 4 years. In multivariate analysis, blood type was not identified as an independent predictor of cardiac complication after major vascular surgery. This is basically a negative study, however the absence of evidencemay not be the same as evidence of absence due to some limitations of this study, including its retrospective nature, relatively small number of patients with short follow up compared to previous studies with 24e26 year follow up, and not including all perioperative and late thrombotic events (venous thromboembolic, graft occlusion, limb ischemia) in their analysis. While the results of this study conflict in part with previous observations, the authors observed significantly higher prevalence of ischemic heart disease (p1⁄4 0.02) in the non-O group at baselinewhereas therewere strong trends in the prevalence of cerebrovascular disease (p 1⁄4 0.08) and hypertension (p1⁄4 0.06) in the O group. Multivariate regression analysis was performed adjusting for several demographic variables, as well as ischemic heart disease. Although this is an accepted statistical method to examine the blood type as an independent contributing factor, it eliminates the interaction between the blood type and the prevalence of the ischemic heart disease.