Lowest Hematocrit on Cardiopulmonary Bypass Impairs the Outcome in Coronary Surgery: An Italian Multicenter Study from the National Cardioanesthesia Database

Background: Severe hemodilutional anemia on cardiopulmonary bypass increases morbidity and mortality after coronary surgery. The present study focuses on the lowest hematocrit values during extracorporeal circulation and on allogenic blood transfusions as mortality and morbidity risk factors.

Methods: The records of 1,766 consecutive adult patients undergoing isolated coronary artery bypass graft surgery at 3 institutions have been analyzed retrospectively for in-hospital mortality and adverse outcomes. Clinical data were from the Italian National Cardioanesthesia Database. Multivariate analysis and analysis of receiver operating characteristic curves were applied.The lowest hematocrit value on cardiopulmonary bypass was an independent risk factor for postoperative low-output syndrome and renal failure. The hematocrit cutoff values were similar for renal failure (23%) and low-output syndrome (24%).

Results: Blood transfusions were significantly associated with both renal failure and low-output syndrome. The risk of renal failure doubled when the nadir-on-cardiopulmonary-bypass hematocrit occurred in transfused patients. Anemia upon cardiopulmonary bypass was not associated with death.

Conclusions: Our findings confirm that both severe anemia and blood transfusions were significantly associated with renal failure and low-output syndrome.