Background: Elevated plasma level of N-Terminal-Pro-B-type Natriuretic Peptide (NT-proBNP, >200 pg/mL) has known to be associated with coronary artery disease (CAD). However, there have been limited data whether the association of NT-proBNP and the coronary artery spasm (CAS). Therefore, we evaluated the impact of NT-pro BNP on the CAS with the intracoronary acetylcholine (Ach) provocation test. Methods: A total 1181 consecutive patients without significant CAD who underwent the Ach provocation test by injecting incremental doses of 20, 50, 100 ug into the left coronary artery were enrolled between March 2004 and April 2009. Significant CAS was defined as focal or diffuse severe transient luminal narrowing (>70%) with/without chest pain or ST-T change on ECG. The Ach provocation test results,its associated parameters and 12 month clinical outcomes were compared between the high NT-proBNP group (>200pg/ml, n=74) and control group (n=1107). Results The clinical and angiographic characteristics were similar between two groups. Although the rate of positive provocation test result was similar between the two groups, the response rate to the lower Ach dose (20關g) was higher and there was a trend toward higher incidence of diffuse CAS in the high NT-proBNP group (Table). Multivariate logistic analysis showed that the high NT-proBNP itself was an independent risk factor for low dose (20關g) Ach- induced CAS (odd ratio; 2.65, 95% confidence interval; 1.36-5.15, p=0.004).12 month clinical outcomes including the rate of death (2.7% vs 0.0%, p<0.01), myocardial infarction (1.4% vs 0.0%, p=0.05) were more common in high NT-proBNP groups. Conclusion: In our study, NT-proBNP level tended to be associated with diffuse CAS and was an independent predictor for the low Ach dose (20關g) induced CAS. Furthermore, high NT-proBNP was associated with 12 month clinical outcome including death and MI. We suggest that elevated NT-proBNP may play an important and sensitive role in assessing pts with suspected vasospastic angina.