Postoperative Prognostic Implementation of BNP in Non Cardiac Surgery with Suspected Cardiac Events

Introduction: It has been suggested that BNP or N-Terminal pro-BNP (NT-proBNP) might be valuable biomarkers to predict mortality and Serious Adverse Events (SAEs), especially in patients with initial normal hemodynamic status.Aim of the Work: The objective of this study was to identify the prognostic value of measuring post-operative [BNP] in those adult patients underwent non-cardiac surgery and suffered or suspected postoperative cardiac complications.Patients and Methods: This limited prospective study concluded, a total of 120 consecutive adult patients who underwent elective non-cardiac surgery that required general anaesthesia and included in the period from September 2012 to August 2014 were studied. The study protocol was done in Critical Care Department, Cairo University.All cases that had suspected to have cardiac events after postoperative non cardiac surgery above 35yr were included in the study. Patients were excluded if having a massive perioperative bleeding or those on renal dialysis. In addition to routine postoperative evaluation, a blood sample was taken for estimation of plasma BNP concentration.Results: The mean age of the patients was 57.7+11.7 years and the sex distribution was 76/44 (male/female). The majority of patients (56.6%) were ASA class 1 or II whereas 52 patients (43.3%) belonged to class III or IV. Five patients (4%) had renal insufficiency with creatinine concentrations 2mg/ml; the mean concentration of creatinine in the whole population was 1.19±69mg/ml. During the hospitalisation period (5.7 days ±4.9), ECG changes were obtained in 85 patients (70.8%) of whom suspected to have postoperative cardiac events in this study. Out of 120 studied patients, 19 patients (15.8%) showed previous myocardial infarction, whereas ECG criteria of left ventricular hypertrophy in 9 patients (7.5%) and left bundle branch block in 4 patients (3.3%). However ECG was normal in 35 patients (29.2%). On the other hand 7 patients (5.8%) had an echo cardiographic data of left ventricular hypertrophy in the studied patients admitted to ICU by suspected cardiac events. Whereas 8 patients (6.6%) were discovered by serial cardiac enzyme values and troponin to have myocardial infarction one of them had previous history of ischemic heart disease. More than 65% (79 patients) weremajor surgeries, whereas abdominal surgery in 44 patients (36.6%), orthopaedic procedures in 39 patients (32.5%), peripheral vascular surgery in 12 patients (10%), head and neck in 11 patients (9.1%), obstetric and gynaecological in 9 (7.5%), and lastly neurosurgery in 5 patients (4.1%).Nine patients with raised BNP ( 250pg/ml) had major events (pulmonary oedema in five patients and myocardial infarction in four patients). Furthermore, 36 patients without an intervening event had low BNP concentrations below (30 pg/ml). Forty six percent of patients with negative troponin also have a positive BNP. Patients with postoperative hospital stays of 12 days or more had high BNP (313±53pg/ml vs. 166 ±37pg/ml). The results of multivariate analysis for predictors of mortality showed that elevated post-operative BNP was the strongest independent predictor of the primary outcome at 30 days after APACHE II score (odds ratio: 4,43; 95% confidence interval: (2.65-6.58) (p-value 0.01).Conclusion: Our data suggest that using concentrations of BNP to predict the prognosis of persons suspected to have cardiac events in non cardiac surgery could be useful as those patients with high levels BNP had longer hospital stays and increased morality.