The prediction of adverse outcomes following major non-cardiac surgery

RC Internal medicine;RD Surgery

Payne, Christopher Jeremy ; Jardine, Alan

University:University of Glasgow

Department:Institute of Cardiovascular and Medical Sciences

关键词: Non-cardiac surgery, adverse outcomes, major adverse cardiac event, vascular;   

Others  :  http://theses.gla.ac.uk/4876/1/2014payneMD.pdf

来源: University of Glasgow

【 摘 要 】

The prediction of adverse outcomes following major non-cardiac surgery is complex.Clinical variables and risk factors, functional status, electrocardiography and non-invasive cardiac investigations can all be used to assess and stratify the risk of post-operative cardiac morbidity or mortality.Multiple factors can be combined into bed-side scoring systems.Increasingly, cardiac biomarkers such as b-type natriuretic peptide (BNP) have been shown to predict heart failure and mortality in non-surgical populations. In the studies in this thesis, I have investigated the incidence of peri-operative cardiac morbidity and mortality in patients undergoing major non-cardiac surgery and identified clinical variables that predicted adverse outcomes.I have tested the utility of BNP for prediction of cardiac complications.I have investigated the long-term survival of the patients in the cohort to identify predictors of reduced survival.I have examined the predictive value of the pre-operative 12-lead ECG for adverse outcomes.I have also studied the utility of a commonly used risk scoring system, the revised cardiac risk index (RCRI), for prediction of cardiac events.The study was a prospectively performed observational study of consecutive patients undergoing major surgery.The cohort consisted of patients undergoing aortic surgery (25.8%), lower limb bypass surgery (29.8%), amputation (25.2%) and laparotomy (20.0%).The patients underwent post-operative screening for myocardial infarction; consisting of serial ECG and troponin measurement.The end-points were major adverse cardiac event (MACE), defined as myocardial infarction or cardiac death and all-cause mortality.Long term follow-up was performed following discharge. Three hundred and forty-five patients were recruited to the trial.Forty-six patients (13.3%) suffered a peri-operative MACE and twenty-seven patients (7.8%) died in the post-operative period (six weeks).Independent predictors of peri-operative MACE were pre-operative anaemia, urgent surgery, a history of hypertension and age > 70 years.Pre-operative BNP was significantly higher in patients who subsequently went on to have a peri-operative MACE, compared with those who did not.An elevated BNP was an independent predictor of both MACE and peri-operative mortality on multivariate analysis.A low BNP was highly indicative of an uneventful post-operative period, with a negative predictive value of 96% for MACE and 95% for all-cause mortality.Traditional clinical markers of heart disease, such as past history of ischaemic heart disease, prior myocardial infarction, cerebro-vascular disease or history of cardiac failure provided no predictive utility for either MACE or mortality. The mortality rate at 1 year was 19.1%.The median follow-up period was 953 days (IQR 661-1216 days).Age > 70 years, diabetes, hypertension, renal impairment, a history of left ventricular failure, anaemia and urgent surgery were associated with reduced long-term survival.A BNP concentration of 87.5 pg/ml provided the best combined sensitivity and specificity for prediction of long-term mortality.Patients with an elevated BNP (>87.5 pg/ml) had a significantly reduced survival and BNP >87.5 pg/ml independently predicted reduced survival on Cox regression analysis.Urgent surgery and anaemia were also independent predictors of reduced long-term survival.An abnormal ECG was observed in 41% of patients recruited.An abnormal ECG was associated with an increased peri-operative MACE and mortality rate.Ventricular strain and prolonged QTc (>440ms) were ECG abnormalities that predicted MACE on multivariate analysis.Patients with an abnormal ECG, but no prior cardiac history, represent a high risk group that may benefit from optimisation.The studies in this thesis have identified that BNP, a simple pre-operative blood test, provides valuable information regarding the risk of both peri-operative morbidity and mortality, and long-term survival after major non-cardiac surgery.Improved risk stratification could allow targeted intervention and medical optimisation prior to surgery with the aim of modifying the risk of adverse outcomes.