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

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.