A prospective observational study of preoperative natriuretic peptide testing in adult non-cardiac surgical patients in hospitals in Western Cape Province, South Africa

Background. International guidelines recommend risk stratification to identify high-risk non-cardiac surgical patients. It is also recommended that all patients aged ≥45 years with significant cardiovascular disease should have preoperative natriuretic peptide (NP) testing. Abnormal preoperative B-type NPs have a strong association with postoperative cardiac complications. In South African hospitals, it is not known how many patients with significant cardiovascular disease scheduled for intermediate- to high-risk surgery will have raised NPs. Objectives. To determine the prevalence of abnormal (raised) NPs in non-cardiac surgical patients with cardiac clinical risk factors. A secondary objective was to develop a model to identify surgical patients who may benefit from preoperative NP screening. Methods. The inclusion criteria were patients aged ≥45 years presenting for elective, non-obstetric, intermediate- to high-risk non-cardiac surgery with at least one of the following cardiovascular risk factors: a history of ischaemic heart disease or peripheral vascular disease (coronary equivalent); a history of stroke or transient ischaemic attack; a history of congestive cardiac failure; diabetes mellitus currently on an oral hypoglycaemic agent or insulin; and serum creatinine level >175 µmol/L (>2.0 mg/dL). Blood samples for N-terminal-prohormone B-type NP (NT-proBNP) were collected before induction of anaesthesia. The preoperative prognostic threshold for abnormal (raised) NT-proBNP was ≥300 pg/mL. A generalised linear mixed model was used to determine the association between the risk factors and an abnormal NT-proBNP level. Results. Of 172 patients, 63 (37%) had an elevated preoperative NT-proBNP level. The comorbidities independently associated with elevated preoperative NT-proBNP were coronary artery disease or peripheral vascular disease, congestive cardiac failure, diabetes mellitus, and a creatinine level >175 µmol/L. Conclusions. We strongly recommend that non-cardiac surgical patients aged ≥45 years undergoing intermediate- or high-risk non-cardiac surgery with a history of coronary artery disease/peripheral vascular disease, congestive cardiac failure, diabetes mellitus or elevated creatinine have preoperative NP testing as part of risk stratification.