Coronary artery bypass grafting in octogenarians: a nomogram for predicting all-cause mortality

Abstract

Abstract Background The benefits and risks of coronary artery bypass grafting (CABG) in octogenarians remain unclear. This study aimed to identify the predictors of increased risk of all-cause mortality in octogenarian patients after CABG. Methods We retrospectively analyzed the data of 1636 octogenarians who underwent isolated elective on-pump CABG between 2007 and 2016. The primary endpoint was mortality from any cause. The Kaplan–Meier curve was generated for mortality. A univariate Cox regression was performed for preprocedural and procedural variables. The Akaike information criterion (AIC) using the Cox proportional hazard model was applied to determine the strongest predictors. We designed a nomogram based on the selected variables to calculate the mortality risk after one, five, and ten years. The bootstrap resampling based on the C-index was performed to validate the final model. Calibration plots were created at different time points. Results The mean age of the patients was 82.03 years (SD = 1.74), and 74% were male. In a median follow-up of 9.2 (95% CI 9.0,9.5) years, 626 (38.2%) patients died. After the selection of best predictors based on AIC, the multivariable Cox regression showed that ejection fraction < 40 (HR 1.41, 95% CI 1.21–1.65, P < 0.001), two-vessel disease (HR: 0.59, 95% CI 0.40–0.89, P = 0.012), peripheral vascular disease (HR 1.52, 95% CI 1.05–2.21, P = 0.027), and valvular heart disease (HR 1.45, 95% CI 1.24–1.69, P < 0.001) were the significant predictors of all-cause mortality. Conclusion Octogenarians who undergo CABG have a high mortality risk, influenced by several preprocedural and procedural risk factors. The proposed nomogram can be considered for optimizing the management of this vulnerable age group. Clinical registration number IR.TUMS.THC.REC.1400.081. Graphical abstract

Keywords

• Coronary artery bypass
• Octogenarians
• Risk factors
• Nomograms
• Mortality