Renin-angiotensin system inhibitors and troponin elevation in spinal surgery

Renin-angiotensin system (RAS) inhibition by angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB) has been shown to reduce cardiovascular mortality and non-fatal myocardial infarction (MI) in high-risk surgical patients. However, their effect in spinal surgery has not been explored. Our objective was to determine the effect of RAS inhibitors on postoperative troponin elevation in spinal fusions, and to examine their correlation with hospital stay. We retrospectively analyzed 208 consecutive patients receiving spinal fusions ⩾5 levels between 2007-2010 with a mean follow-up of 1.7 years. Inclusion criteria were age ⩾18 years, elective fusions for kyphoscoliosis, and semi-elective fusions for tumor or infection. Exclusion criteria were trauma and follow-up <1 year. Descriptives, frequencies, and logistic and linear regression were used to analyze troponin elevation (⩾0.04 ng/mL), peak troponin level, and hospital stay. The results featured 208 patients with a mean body mass index (BMI) 28.5 kg/m(2) who underwent 345 spinal fusions. ACEI/ARB were withheld the day prior to surgery in 121 patients with 11 patients noteworthy for intra-operative electrocardiogram changes, 126 patients with troponin elevation, and 14 MI identified prior to discharge. Multivariate logistic regression identified BMI (p=0.04), estimated blood loss (p=0.015), and preoperative ACEI/ARB (p=0.015, odds ratio=2.7) as significant independent predictors for postoperative troponin elevation. Multivariate linear regression showed preoperative Oswestry Disability Index (p=0.002), unplanned return to operating room (p=0.007), pneumonia prior to hospital discharge (p<0.01), and preoperative ACEI/ARB to be associated with hospital stay. In patients with spinal fusions ⩾5 levels, ACEI/ARB are independently associated with postoperative troponin elevation and increased hospital stay.