Use of B-type natriuretic peptide in the detection of myocardial ischemia

Exercise electrocardiography (ECG) has high specificity but limited sensitivity for the detection of myocardial ischemia. The aim of this study was to determine whether measurement of B-type natriuretic peptide (BNP) can improve the diagnostic accuracy of exercise ECG.

A total of 256 consecutive patients with suspected myocardial ischemia referred for rest/ergometry myocardial perfusion single-photon emission computed tomography were enrolled. Levels of BNP were determined before and 1 minute after maximal exercise.

Inducible myocardial ischemia on perfusion images was detected in 127 patients (49.6%). Median BNP levels at rest and after peak exercise were higher in patients with than without inducible ischemia (71 pg/mL vs 38 pg/mL, P < .001; and 88 vs 52 pg/mL, P < .001, respectively). Compared with patients in the lowest peak exercise BNP quartile, those in the highest quartile of peak exercise BNP had more than 3 times the risk of inducible ischemia (adjusted relative risk 3.3, 95% CI 1.3-8.6, P = .015). Using 110 pg/mL as a cutoff, the combination of exercise ECG and peak exercise BNP level distinguished between ischemic and nonischemic patients more accurately than the exercise ECG alone (67% vs 60%, P = .024). Although the increase in accuracy was similar for the combination of exercise ECG with baseline BNP or DeltaBNP, overall, peak exercise BNP seemed to be the preferred measurement.

B-type natriuretic peptide levels are associated with inducible myocardial ischemia. The use of BNP levels improves the diagnostic accuracy of exercise ECG.