Colectomy due to Ischemic Colitis after Heart Surgery: A Matched-pairs Analysis

Objectives: Ischemic colitis remains a great threat after heart surgery with use of extracorporeal circulation. We aimed to identify predictive risk factors and influence of early catecholamine therapy for this disease.

Methods: Out of 15,162 patients operated with help of ECC at our institution during 2002 and 2014, 224 patients underwent colectomy after initial heart surgery. For precise comparability 58 patients were identified who underwent coronary bypass surgery, aortic valve replacement or combination of both. Age ± 5 years, sex, BMI ± 5, left ventricular function, peripheral arterial disease, diabetes and urgency status were used for match-pair analysis (1:1) to compare outcome and detect predictive risk factors.

Results: Patients' baseline characteristics showed no significant differences. In-hospital mortality of the colectomy group with a mean age of 70.81 years (13.8% female) was significantly higher than the control group with a mean age of 70.41 (13.8% female) (67% versus 15.5%, p< 0.001). Despite significantly longer bypass times in the colectomy group (133 ± 68 versus 101 ± 42, p = 0.003), cross-clamp time remained comparable (64 ± 33 versus 56 ± 25 p = 0.150). Interestingly, bicaval cannulation was used more often in the colectomy group (43% versus 21%, p = 0.016). The majority of the colectomy group suffered low-output syndrome (71% versus 14%, p< 0.001) leading to significant higher lactate values within first 24h after operation (54.57 ± 45.80 mg/dl versus 31.04 ± 30.19 mg/dl, p = 0.002). Logistic regression revealed elevated lactate values to be significant predictor for colectomy during the postoperative course (OR 1.018, CI 95% 1.005–1.031, p = 0.005). However, Receiver Operating Characteristic Curve (ROC) calculates a vague cut-off value for lactate of 20.5 mg/dl (sensitivity 83.9% and specificity 50.0%). Furthermore, multivariate analysis showed that low-output syndrome (OR 16.322, CI 95% 5.9–45.151, p< 0.001) and right atrial cannulation (OR 0.323, CI 95% 0.117–0.891, p = 0.029) did significantly influence necessity of colectomy. The colectomy group had significant higher norepinephrine (p = 0.001) and vasopressin doses (p< 0.001) within first postoperative 24h.

Conclusion: Patients who undergo colectomy after initial heart surgery have a substantial in-hospital mortality risk. Early postoperative catecholamine levels may influence the development of an ischemic colitis with need of resection. Elevated lactate levels remain a significant predictive risk factor.