Prognostic implications of preoperative chronic kidney disease and anemia in patients undergoing coronary artery bypass graft surgery

Mortality across the spectrum of hemoglobin level in patients undergoing surgical coronary revascularization

BACKGROUND

Preoperative hemoglobin (Hb) level is a predictor of in-hospital and midterm mortality in patients undergoing coronary artery bypass grafting surgery (CABG). However, the debate about the different hazards across Hb levels and sex differences in outcome occurrence is still on the table.

METHODS

This is a registry-based serial cross-sectional study at Tehran Heart Center. Nonanemic patients who underwent CABG with complete follow-up data were included. The Restricted Cubic Splines (RCS) in the Cox model was used to calculate the sex-specific correlation between in-hospital, 6-month, and 1-year mortalities and normal Hb levels using odds ratio for the in-hospital and hazard ratios for 6-month and 1-year mortality, adjusted for all possible confounders.

RESULTS

From 2005 to 2016, a total of 13,557 patients were included, of which 134 had in-hospital mortality as our primary outcome. Preoperative Hb levels were significantly lower in the deceased. Moreover, dead patients had significantly higher rates of diabetes and hypertension, while lower ejection fraction. Cut-offs for reference Hb level were higher for males compared with females. The correlation between Hb level and in-hospital mortality was nearly U-shaped. Quantitatively, Hb of ≥15.62 and ≤13.25 g/dL for men and that of ≥14.92 and ≤13.4 g/dL for women tended to be associated with higher in-hospital mortality.

CONCLUSIONS

The association between preoperative Hb level and in-hospital mortality differs in men and women and does not follow a linear correlation among nonanemic patients. Both low and high numbers in the Hb level spectrum are at greater risk.

Early postoperative bleeding impacts long-term survival following first-time on-pump coronary artery bypass grafting

Background

Significant bleeding following cardiac surgery is a recognised complication, associated with a requirement for re-exploration and blood transfusion, both associated with increased morbidity and early mortality. The aim of this study was to examine the impact of the volume of early postoperative bleeding on long-term survival for patients undergoing coronary artery bypass grafting (CABG).

Methods

A retrospective analysis was performed of patients undergoing first-time isolated CABG at a single centre between January 2003 and April 2013, conditional from 30-day survival.

Results

Six thousand two hundred and sixty-five patients were analysed, with a mean Logistic EuroSCORE of 4.9%. The mean age was 67.8 years. Median follow-up was 11.5 years. The overall 10- and 15-year survival was 70.6% and 51.9% respectively. Following surgery, 4.6% (n=291) required return to theatre for re-exploration, and 43.6% (n=2,733) received at least one red cell transfusion. In multivariable analysis, the strongest correlates of mortality were age, smoking history, BMI, COPD, renal impairment, preoperative left ventricular function and preoperative haemoglobin (Hb) level. Twelve-hour blood loss was an additional predictor of inferior long-term survival. Five-year survival was 89.6% for patients with <500 mL blood loss, 86.8% for 500–1,000 mL and 83.8% for >1,000 mL. Re-exploration and receiving blood transfusion were not associated with reduced long-term survival.

Conclusions

Significant 12-hour blood loss is associated with inferior long-term survival following CABG. This observation supports efforts aimed at improving intra-operative haemostasis and aggressive management of patients with early signs of bleeding.

Prognostic Interplay of Chronic Kidney Disease, Anemia, and Diabetes in Coronary Bypass Surgery

BACKGROUND

Chronic kidney disease and anemia often coexist and may accompany diabetes; all 3 conditions are associated with worse cardiovascular outcomes. This study investigated the prognostic implications of anemia and chronic kidney disease for mortality among patients undergoing coronary artery-bypass grafting surgery and examined whether outcomes are related to the presence of diabetes.

METHODS

This retrospective study included 1180 patients undergoing coronary artery-bypass grafting. Long-term mortality (mean follow-up, 8.6 ± 4.2 years) was examined in relation to preoperative anemia, chronic kidney disease, and diabetes. Prognostic interplay of the 3 risk factors was evaluated.

RESULTS

Chronic kidney disease, anemia, and diabetes (20%, 25%, and 43% of patients, respectively), were independent risk predictors for mortality. Compared with patients with neither chronic kidney disease nor anemia, the adjusted hazard ratios (HRs) for mortality were 1.87 (95% confidence interval [CI], 1.35 to 2.59) in chronic kidney disease only, 1.75 (95% CI, 1.30 to 2.35) in anemia only, and 2.69 (95% CI, 1.91 to 3.78) in patients with both conditions. The pattern of association of chronic kidney disease and anemia with mortality was similar in patients with and without diabetes. However, mortality risk was higher in patients with diabetes in each risk category-neither chronic kidney disease nor anemia: HR, 1.69 (95% CI, 1.20 to 2.39) vs HR, 1 (reference); chronic kidney disease only: HR, 2.68 (95% CI, 1.59 to 4.52) vs HR, 2.10 (95% CI, 1.38 to 3.20); anemia only: HR, 2.73 (95% CI, 1.83 to 4.07) vs HR, 1.94 (95% CI, 1.23 to 3.08); and both chronic kidney disease and anemia: HR, 4.44 (95% CI, 2.88 to 6.85) vs HR, 2.72 (95% CI, 1.58 to 4.69).

CONCLUSIONS

In patients undergoing coronary artery-bypass grafting, anemia and chronic kidney disease have significant prognostic implications for long-term mortality. Their effect on mortality was cumulatively associated with adverse impacts of diabetes.