Cardiac Blood Test Predicts Post-Surgical Outcomes

Globally, of the 200 million adults who undergo major surgery, 18% will experience serious cardiac and vascular complications including death within 30 days following their intervention, such as hip and knee replacements, bowel resections and abdominal aortic aneurysm repair.

Results of a simple blood test may inform the type of surgery the patient will undergo, such as laparoscopic or open surgery, the type of anesthesia used during surgery and who will require more intense monitoring post-operatively. Blood test results can also reduce the need for pre-surgical medical consultations for patients that show no risk for cardiac complications.

A large international team of medical scientists led by those at McMaster University (Hamilton, ON, Canada) looked at whether levels of a cardiac blood test, N-Terminal Pro–B-Type Natriuretic Peptide (NT-proBNP), measured before surgery can predict cardiac and vascular complications. Higher levels of NT-proBNP, which can be caused by various anomalies in the cardiac muscle, such as stress, inflammation or overstretch, can help identify which patients are at greatest risk of cardiac complications after surgery.

The study included 10,402 patients aged 45 years or older having non-cardiac surgery with overnight stay from 16 hospitals in nine countries. The team determined whether preoperative NT-proBNP has additional predictive value beyond a clinical risk score for the composite of vascular death and myocardial injury after non-cardiac surgery (MINS) within 30 days after surgery. All patients had NT-proBNP levels measured before surgery and troponin T levels measured daily for up to three days after surgery.

The investigators reported that in multivariable analyses, compared with preoperative NT-proBNP values less than 100 pg/mL (the reference group), those of 100 to less than 200 pg/mL, 200 to less than 1,500 pg/mL, and 1,500 pg/mL or greater were associated with adjusted hazard ratios of 2.27, 3.63, and 5.82 and corresponding incidences of the primary outcome of 12.3% (226/1,843), 20.8% (542/2,608), and 37.5% (223/595), respectively. Adding NT-proBNP thresholds to clinical stratification resulted in a net absolute reclassification improvement of 258 per 1,000 patients. Preoperative NT-proBNP values were also statistically significantly associated with 30-day all-cause mortality (less than 100 pg/mL [incidence, 0.3%], 100 to less than 200 pg/mL [incidence, 0.7%], 200 to less than 1,500 pg/mL [incidence, 1.4%], and 1,500 pg/mL or greater [incidence, 4.0%]).

Emmanuelle Duceppe, MD, an internist and first author of the study, said, “This simple blood test can be done quickly and easily as part of patient's pre-operative evaluation and can help patients better understand their risk of post-operative complications and make informed decisions about their surgery. This blood test is twenty times cheaper than more time-consuming tests such as cardiac stress tests and diagnostic imaging.” The study was published on December 24, 2019 in the journal Annals of Internal Medicine.

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