Myocardial protection with insulin cardioplegia: who can really benefit?

AIM: The aim of the study was to evaluate the effects on myocardial protection of insulin-enriched warm blood cardioplegia (IWBC) in coronary artery bypass grafting (CABG) and in subgroups of patients with associated cardiac co-morbidities. METHODS: Between May 2000 and December 2002, 268 consecutive patients underwent CABG with warm blood cardioplegia (group A) or IWBC (10 UI/L) (group B). Hospital outcome, ECG, echocardiography and biochemical markers of ischemia were compared. Differences between subgroups of patients with unstable angina (UA), ventricular hypertrophy (VH) and diabetes were assessed. RESULTS: Hospital mortality, incidence of postoperative myocardial infarction and low output syndrome, IABP requirement, postoperative atrial fibrillation, in-hospital and in-ITU stay, postoperative recovery of left ventricular function and enzyme leakage did not show differences between the 2 groups; inotropic support was lower in IWBC. Moreover, patients with UA and IWBC showed a lower troponin I (TnI) (12 h: 0.82+/-0.57 ng/mL vs 2.56+/-1.18, P < 0.0001; 24 h: 0.71+/-0.64 vs 2.16+/-1.52, P < 0.0001; 48 h: 0.69+/-1.13 vs 1.79+/-1.43, P = 0.001; 72 h: 0.44+/-0.83 vs 1.01+/-1.02, P = 0.001), lower incidence of atrial fibrillation (4.2% versus 60.6%; P < 0.0001) and intraoperative defibrillation (0% versus 27.3%; P = 0.007). Furthermore, patients with VH treated with IWBC showed lower level of TnI (12 h: 0.41+/-0.32 ng/mL vs 2.93+/-0.67, P < 0.0001; 24 h: 0.37+/-0.45 vs 2.40+/-1.28, P < 0.0001; 48 h: 0.22+/-0.18 vs 1.95+/-1.33, P < 0.0001; 72 h: 0.12+/-0.12 vs 1.31+/-1.56, P < 0.0001), lower atrial fibrillation (6.5% vs 48%, P < 0.0001) and ventricular defibrillation (0% vs 20%, P = 0.011). CONCLUSIONS: Insulin addiction to blood cardioplegia does not show any benefit in the global population and in diabetics; nevertheless, better myocardial protection can be demonstrated in patients with unstable angina and left ventricular hypertrophy.