Seizures after cardiac surgery: A systematic review

Background: Postoperative seizures are multifactorial and have a possibly underestimated impact on patient outcomes. This systematic review aims to analyze the occurrence rate of postoperative seizures and investigate their effect on outcomes. Methods: The review was conducted following Preferred Reporting Items for Systematic reviews and Meta- Analyses (PRISMA) 2020 guidelines. A comprehensive search of PubMed, Embase, and Web of Science was performed on December 9, 2023. Studies eligible for inclusion were prospective and retrospective studies involving adult patients undergoing cardiac surgery. Review articles, case reports, and studies focused on cardiac interventional procedures, heart transplant surgery, infectious endocarditis, neurosurgery, or vascular/ aortic surgery were excluded. Data on seizure occurrence and mortality rates were extracted and analyzed using Excel. Means and interquartile ranges (IQR) were calculated. The risk of bias was assessed using the 2013 Study Quality Assessment Tools from the National Institutes of Health (NIH). Results: Out of 1,644 identified articles, 36 were selected for inclusion. Baseline characteristics revealed heterogeneity in the types of surgery and seizure definitions across the studies. Seizure occurrence rates ranged from 0% to 20% (mean 2.4%, IQR 2.6%) following coronary surgery, 0% to 32.3% (mean 10.4%, IQR 13.1%) following valvular surgery, 0% to 8% (mean 2.3%, IQR 2.1%) in the overall category, and 0% to 9% (mean 2.7%, IQR 2.7%) following open-heart surgery. One study reported a seizure rate of 19.9% for a combined surgery category. In-hospital mortality rates ranged from 1.1% to 29% (mean 12.5%, IQR 13.6%). Discussion: The wide range of seizure occurrence rates observed may be attributable to the heterogeneity between the included studies. Further research is necessary to evaluate the impact of factors such as tranexamic acid (TXA) use, renal function, and other perioperative variables on seizure occurrence. Seizure rates were notably higher following valvular and open-heart surgeries and among patients exposed to TXA. Although limited, available data suggest that patients experiencing seizures may have higher mortality rates, highlighting the need for more robust studies. The review identified a high risk of confounding bias in many of the included studies. Other: This review is registered in The International Prospective Register of Systematic Reviews (PROSPERO) under the identification number CRD42023395374.