Validation of B-type Natriuretic Peptide With N-terminal Pro B-type Natriuretic Peptide in Perioperative Risk Assessment

This is a single-centre, prospective study to determine the correlation and comparative thresholds between NT ProBNP (Roche) and BNP (Abbott) tests. This will involve simultaneous serum sampling for both BNP and NT ProBNP at pre-surgical screening (PSS) or on the day of surgery (DOS). Serum sampling of BNP in this patient population is standard of care in our institution, thus only the additional blood required for the NT ProBNP test requires additional consent. Informed consent will be obtained at PSS or on the DOS by study staff. High sensitivity troponin I (Abbott) measurements will be taken on postoperative day (POD) 0, 1 and 2, as per local standard of care and the outcome of MINS (myocardial injury after non-cardiac surgery as indicated by high sensitivity troponin > 30 ng/L) or vascular death will be determined by an assessor blinded to BNP/NT ProBNP results at postoperative day (POD) 30. The primary outcome is correlation of POC NT ProBNP with BNP levels and validation of appropriate thresholds. The secondary outcome is combined MINS and vascular death at POD 30.

The study population will include patients assessed in PSS or on the DOS who are presenting for elective surgery requiring a minimum of one-night admission following and are a) >65 years old, b) revised cardiac risk index (RCRI) ≥1 or c) >45 years old with significant cardiovascular disease (coronary artery disease, peripheral arterial disease, cerebral vascular disease, congestive heart failure, obstructive intracardiac disease such as severe aortic stenosis, severe mitral stenosis or severe hypertrophic obstructive cardiomyopathy).

The required sample size of 431 patients was calculated to adequately perform a power assessment of the primary outcome of correlating BNP and NT ProBNP thresholds. Historically, Presurgical Screening (PSS) at Kingston Health Sciences Centre (KHSC) collects BNP serum samples from approximately 500 patients at PSS in a six month time frame, as reported by a local, retrospective quality assurance study (McMullen/Cook). This sample size will not likely be sufficient to determine significance regarding the secondary outcome of MINS or vascular death by POD 30. Nonetheless, the trend observed may be informative in the context of correlating the risk prediction provided by BNP screening at our centre to that from larger studies.