Outcomes of Coronary Artery Bypass Grafting (CABG) Patients With and Without a History of Liver Transplant

Background: Liver transplant (LT) patients face various challenges, including an increased risk of coronary artery disease (CAD) for a variety of reasons, with 70% of LT recipients having one cardiovascular event. Coronary artery bypass grafting (CABG) remains one of the most commonly performed major surgical procedures in the United States, with 20-30% of LT patients requiring a CABG. Many studies have analyzed when to perform a CABG and CAD workup pre-LT, but this population remains a problem. The patient population is challenging to study due to their rarity and complexity. Our study aimed to compile many patients through the National Inpatient Sample (NIS) database to gauge the outcomes of CABG in patients with and without a history of LT. Methods: Patients who underwent CABG with or without a history of LT were selected from the NIS from 2008 to 2020. The International Classification of Diseases (ICD) 9 and 10 codes were used to identify suitable records. Primary outcomes of interest were all-cause hospital mortality, shock, acute myocardial infarction, acute kidney injury (AKI), and a composite of these. Secondary outcomes included length of stay and total charges. Results: A weighted total of 2,407,349 CABG hospitalizations were included in this study. Of these, 1,833 had a history of LT. Overall, patients with a history of LT were more likely to be younger (65.16 vs. 66.16; p<0.001), male (81.6% vs. 73.66%; p<0.001), and more complex (Charlson Comorbidity Index (CCI) 5.89 vs. 4.16; p<0.001) than patients without a history of LT. Patients with a history of LT also had higher rates of diabetes mellitus type 2 (57.02% vs. 43.39%; p<0.001), end-stage renal disease (11.21% vs. 2.95%; p<0.001), and gastroesophageal reflux disease (GERD) (28.39% vs. 21.26%; p<0.001). CABG patients with a history of LT were less likely, however, to have hyperlipidemia (56.72% vs. 74.26%; p<0.001), hypertension (25.95% vs. 58.45%; p<0.001), obesity (19% vs. 23.42%; p=0.046), a history of smoking (12.06% vs. 18.66%; p<0.01), or alcohol use disorder (9.04% vs. 13.44%; p=0.017). We found that patients admitted for CABG with a history of LT had significantly higher adjusted odds of mortality (OR 1.84; p<0.01), AKI (OR 2.65; p<0.001), and composite outcome (OR 2.04; p<0.001). They also experienced a longer length of stay (1.7 days; p=0.02) and greater hospital charges ($26,761; p=0.029).

Conclusion: We found that CABG patients with a history of LT had nearly twofold higher odds of mortality, nearly threefold higher odds of AKI, and twofold higher odds of composite outcomes than CABG patients without LT. This corresponded to longer lengths of stay and increased hospital charges. Patients should require lower thresholds for left heart catheterization and more strict CAD testing before an LT due to the increased risk of adverse outcomes with the current standard of care.