Outcomes and Indication-Based Risk Stratification in Redo Cardiac Surgery

Objectives: Redo cardiac surgery is associated with increased perioperative risk requiring a careful and individualized risk stratification in advance as well as detailed patient information. The aim of this study was the identification of perioperative risk factors regarding redo cardiac surgery. Additionally, different indications for redo cardiac surgeries were compared regarding possible procedure-related differences in outcomes.

Methods: A total of 421 patients underwent redo cardiac surgery between 2009 and 2015 at University of Cologne, Heart Center. Patients were divided up into groups depending on the current indication of redo-cardiac-procedure. Patient profiles and clinical outcomes were compared. Independent risk factors connected to in-hospital-death were assessed by chi-square test and multivariate analysis.

Results: The collective (421 patients, 29.7% female) was composed of 128 (30.4%) redo coronary artery bypass grafting (CABG) procedures, 200 redo valvular surgeries (VS 47.5%; 23.7% aortic valves, 12.3% mitral valves, 11.4% combined valvular surgery), 42 (10%) combined surgeries (CS: Valve + CABG), 51 aortic surgeries (AS). Mean in-hospital-mortality was 15.2% (VS: 11.5%, CABG: 19.5%, CS: 21.4%, AS: 9.4%). While the indication of the initial cardiac surgery did not affect in-hospital mortality, the current redo indication did. For isolated CABG and CABG + VS in-hospital-mortality was significantly higher compared with surgeries without CABG (p = 0.015). Neurological events occurred in 7% (VS: 7%, CABG: 3.1%, CS: 4.8%, AS: 13.7%). Postoperative kidney failure occurred in 20.7% (VS: 20.5%, CABG: 18%, CS: 28.6%, AS: 13.7%). Mean MOF rate was 4% (VS: 3%, CABG: 5.5%, CS: 7.1%, AS: 0%). Independent preoperative risk factors for in-hospital-mortality included preoperative kidney insufficiency (p = 0.007; OR 2.66), pAVK (p < 0.001; OR 3.72), CPR within 4 weeks in advance of redo cardiac surgery (p = 0.03; OR: 2.56) and sepsis (p = 0.004; OR: 3.23). Patients who died were significantly more often on statin- (p = 0.018), nitrate- (p < 0.002) and diuretic (p = 0.014) medication in advance of the surgery.

Conclusion: CABG appears to be a risk factor at the time of redo cardiac surgery, showing increased mortality compared with redo cardiac surgery without CABG. Independent preoperative risk factors associated with increased mortality in redo cardiac surgery comprise kidney insufficiency, pAVK, CPR within four weeks in advance of redo cardiac surgery and sepsis.

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