Impact of Ejection Fraction on Infectious, Renal, and Respiratory Morbidity for Patients Undergoing Noncardiac Surgery

Abstract

The purpose of this single-center retrospective cohort study is to assess whether there is an increased risk of postoperative infection, respiratory, or kidney complications in patients undergoing noncardiac surgery who have decreased left ventricular systolic function. Participants were adults who underwent noncardiac surgery during the period January 1, 2005, to December 31, 2010, at the University of Michigan. Respiratory complication was defined as needing postoperative mechanical ventilation for over 48 hours or the occurrence of unplanned intubation. Kidney-related complications were defined as renal insufficiency with a postoperative increase in serum creatinine levels of more than 2 mg/dL or postoperative acute renal failure requiring dialysis. Infectious complications included pneumonia, urinary tract infections, sepsis, and wound infections. An independent association between decreased left ventricular ejection fraction (LVEF, a measure of systolic function) and renal and infectious complications were observed. A decreased LVEF correlated with a 69% increase in the odds of renal complications and a 33% increase in the odds of infectious complications. Amajor strength of this studywas the robustness of the comorbidities and outcomes collected as experienced cardiologists assessed LVEF, while trained experts collected patient and outcome data, unlike the hit-or-miss general administrative databases. Postoperative infections (n = 175 [10%]) were the most common postoperative complication in this study population of 1692 individuals, followed by respiratory complications, which manifested in 77 cases (5%), whereas renal complications occurred in 29 participants (2% of the study population). The time gap between the echocardiogram and surgery spanned from 7months (interquartile range, 1.8–15.7months) for thosewith severely reduced LVEF to 24 months (interquartile range, 2.5–38.6 months) for those with a normal LVEF (P = 0.038). A univariate statistical analysis supported a relationship between decreased preoperative LVEF and complications from infections and of the kidney but not respiratory complications. After adjusting for preoperative characteristics, decreased preoperative LVEF was associated with infectious complications (odds ratio, 1.33; 95% confidence interval, 1.03–1.68; P = 0.0265) and renal complications (odds ratio, 1.69; 95% confidence interval, 1.12–2.48; P = 0.0142). Thus, the findings of this study can help clinicians better balance the risks and benefits of various therapies as it emphasizes the noncardiac complications that can arise in patients with preexisting cardiac dysfunction undergoing noncardiac surgery. Published data exist on the association of increased major adverse cardiac events in patients with a known history of heart failure, but less is known on risk to other organ systems. The researchers from the University of Michigan have elucidated the effects of decreased LVEF in regard to infectious, renal, and respiratory complications after noncardiac surgery.