# Coronary Artery Bypass Surgery in Patients on Dialysis: In-Hospital Outcomes from UK Registry Analysis

## TL;DR

Patients on dialysis who undergo heart bypass surgery face higher in-hospital mortality and complications compared to non-dialysis patients, according to a UK registry analysis.

## Contribution

This study provides new insights into the risks and outcomes of coronary artery bypass surgery in dialysis patients using a large national registry.

## Key findings

- Dialysis patients had a 7.9% in-hospital mortality rate compared to 2.1% in non-dialysis patients.
- EuroSCORE 2 performed poorly in predicting mortality for dialysis patients.
- Dialysis patients had longer hospital stays and higher rates of return to theatre for bleeding.

## Abstract

Chronic kidney disease requiring dialysis significantly increases the risks of coronary artery disease. However, there is limited data on this high-risk patient population requiring coronary artery bypass grafting. Using a UK national registry, we investigated the impact of preoperative dialysis on in-hospital mortality and early morbidity in patients undergoing coronary artery bypass graft (CABG).

A retrospective analysis of National Adult Cardiac Surgery Audit data between January 1996, 2, and March 31, 2019, identified patients who underwent first-time isolated CABG. Propensity matching was performed to balance the baseline characteristics between dialysis and non-dialysis patients, yielding 633 matched pairs. We evaluated trends in CABG among dialysis patients and EuroSCORE 2 performance in predicting in-hospital mortality (calibration, discrimination, and clinical utility).

There was a steep increase in CABG operations in dialysis patients after 2011. EuroSCORE 2 showed poor calibration, discrimination, and minimal clinical benefit in predicting mortality in dialysis cases. Dialysis patients exhibited a significantly higher in-hospital mortality rate (7.9% vs 2.1%, P < .001) than non-dialysis patients. The dialysis patients had longer median hospital stays (12 vs 9 days, P < .001) and a higher rate of return to the theatre for bleeding (5.5% vs 2.7%, P = .034). We found no difference in postoperative neurological deficit rates between the 2 cohorts. The odds ratio of in-hospital mortality for the dialysis vs non-dialysis patients was 4.62, P < .001, 95% (CI: 2.54-8.4). Significant predictors of mortality in the dialysis CABG cohort included advanced age (OR: 2.48), New York Heart Association class IV (OR: 3.06), and pulmonary hypertension (OR: 11.91).

There has been an overall increase in coronary artery bypass operations performed in renal dialysis-dependent patients in the UK. Preoperative chronic dialysis is associated with considerable in-hospital mortality, return to theatre for bleeding and prolonged hospital stay. EuroSCORE 2 has poor predictive performance in this patient cohort.

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide,1 particularly among patients with chronic kidney disease (CKD).