Delayed release of brain natriuretic peptide to identify myocardial ischaemia

Background A recent pilot study suggested that exercise‐induced myocardial ischaemia may lead to a delayed release of cardiac biomarkers, so that later sampling, for example, at 4 h after exercise could be used for diagnostic purpose. Materials and methods In an observational study, we enrolled 129 consecutive patients referred for evaluation of a suspected coronary artery disease by rest/stress myocardial perfusion single‐photon emission computed tomography. The treating cardiologist used all available clinical information to quantify clinical judgment regarding the presence of myocardial ischaemia using a visual analogue scale twice: prior and after stress testing. BNP levels were determined in a blinded fashion at rest, at peak stress and 4 h after peak stress. The presence of myocardial ischaemia was adjudicated based on perfusion single‐photon emission computed tomography and coronary angiography findings by an independent cardiologist. Results Myocardial ischaemia was detected in 58 patients (45%). Patients with myocardial ischaemia had significantly higher BNP levels at all times, compared to patients without ischaemia: BNP rest (99 vs. 61 pg/mL P = 0·007), BNP stress (125 vs. 77 pg/mL P = 0·02) and BNP 4 h (114 vs. 71 pg/mL P = 0·018). Diagnostic accuracy as quantified by the area under the receiver operating characteristics curve ( AUC ) was moderate for all time points ( AUC 0·64–0·66). The change in BNP between rest and 4 h did not provide added value, neither to the baseline BNP level nor to clinical judgment. Conclusion In contrast to our hypothesis, myocardial ischaemia did not lead to a differential delayed release of BNP . Late sampling did not seem clinically useful.