Impact of early quantitative morbidity on 1-year outcomes in coronary artery bypass graft surgery

Abstract

Objectives: We applied the Clavien-Dindo Complications Classification (CDCC) and the Comprehensive Complication Index (CCI) to the CORONARY trial to assess whether quantitative early morbidity affects outcomes at 1 year.

Methods: All postoperative hospitalization and 30-day follow-up complications were assigned a CDCC grade. CCI were calculated for all patients (n = 4752). Kaplan-Meier analysis examined 1-year mortality and 1-year co-primary outcome (i.e. death, non-fatal stroke, non-fatal myocardial infarction, new-onset renal failure requiring dialysis or repeat coronary revascularization) by CDCC grade. Multivariable logistic regression evaluated the predictive value of CCI for both outcomes.

Results: For off-pump and on-pump coronary artery bypass graft surgery, median CDCC were 1 [interquartile range: 0, 2] and 2 [1, 2] (P < 0.001), while median CCI were 8.7 [0, 22.6] and 20.9 [8.7, 29.6], respectively (P < 0.001). In on-pump, there were more grade I and grade II complications, particularly grade I and II transfusions (P < 0.001) and grade I acute kidney injury (P = 0.039), and more grade IVa respiratory failures (P = 0.047). Patients with ≥IIIa complications had greater cumulative 1-year mortality (P < 0.001). The median CCI was 8.7 [0, 22.6] in patients who survived and 22.6 [8.7, 44.3] in patients who died at 1 year (P < 0.001). The CCI remained an independent risk factor for 1-year mortality and 1-year co-primary outcome after multivariable adjustment (P < 0.001).

Conclusions: On-pump coronary artery bypass graft surgery had a greater number of complications in the early postoperative period, likely driven by transfusions, respiratory outcomes and acute kidney injury. This affects 1-year outcomes. Similar analyses have not yet been used to compare both techniques and could prove useful to quantify procedural morbidity.

Clinical trial registration: https://www.clinicaltrials.gov/ct2/show/NCT00463294; Unique Identifier: NCT00463294.

Keywords: Clavien-Dindo Complications Classification; Comprehensive Complication Index; Coronary artery bypass graft surgery; Outcomes; Quantitative morbidity.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.

Figures

Figure 1:

Distribution of CDCC grades for early postoperative morbidity in patients undergoing off-pump CABG and on-pump CABG. CABG: coronary artery bypass graft surgery; CDCC: Clavien-Dindo Complications Classification.

Figure 2:

(A) Kaplan–Meier curves for cumulative mortality at 1 year in the entire cohort of patients who survived the early 30-day period based on postoperative Clavien-Dindo Complications Classification grade. (B) Kaplan–Meier survival curves for cumulative co-primary outcome (i.e. death, non-fatal stroke, non-fatal myocardial infarction, new-onset renal failure requiring dialysis or repeat coronary revascularization) at 1 year in the entire cohort of patients who survived the early 30-day period based on Clavien-Dindo Complications Classification grade. Patients with the occurrence of the co-primary outcome within 30 days were excluded.

Figure 3:

Kaplan–Meier survival curves for cumulative mortality at 1 year in patients who underwent (A) off-pump or (B) on-pump CABG and who survived the early 30-day period based on CDCC grade. CABG: coronary artery bypass graft surgery.

Figure 4:

Kaplan–Meier survival curves for cumulative co-primary outcome (i.e. death, non-fatal stroke, non-fatal myocardial infarction, new-onset renal failure requiring dialysis or repeat coronary revascularization) at 1 year in patients who underwent off-pump or on-pump CABG who survived the early 30-day period based on Clavien-Dindo Complications Classification grade. Patients with occurrence of the co-primary outcome within 30 days were excluded. CABG: coronary artery bypass graft surgery.

Figure 5:

Receiver operating characteristic curves with area under the receiver operating characteristic curve and 95% confidence interval comparing the predictive ability of the multivariable logistic models with or without CCI for (A) 1-year mortality and (B) 1-year co-primary outcome. The models excluded patients who had reached the outcome within 30 days, and the CCI excluded the score of patients who had died within 30 days.