Background and method : Hemodynamic responses and interactive parameters to acetylcholine provocation test for confirmation of vasospastic angina was monitored during coronary angiogram in patients without significant coronary atherosclerosis. Result : In patients with atypical chest pain, total 241 patients (M/F=1.06) were enrolled for this study. During provocation test, coronary stenoses over 70% compared to control images and relieved by intracoronary nitroglycerine as positive. Of these patients, 157 patients (65.1%,) showed positive findings especially in male gender (M/F=1.30, p=0.026). Baseline heart rate was lower in positive respoen group (68.9짹12.4 vs. 71.7짹12.7, p=0.28) and transient bradycardia (heart rate variability) response in early phase of acetylcholine was frequent in positive provocation group (-0.88짹6.47/min vs. 0.84짹4.71/min, p=0.40). Notably, there have been more atrioventricular block responses during dose escalation of acetylcholine from 20關g, 50關g, to 100關g, however, there was no significant blood pressure change and trends for non-significant increase in systolic and diastolic blood pressure during dose escalation which was unexpected responses of acetylcholine as vasodilator and showed its safety for provocative usage to intracoronary injection. In multiple logistic regression, transient bradycardia was the only meaningful predictor for vasospasm (HR=0.83, 95% CI 0.87 to 0.99, p=0.32). Conclusion: chronotropic response such as bradycardia compared to inotropic responses was more prominent during acetylcholine provocation test in patient with vasospasm and its hemodynamic monitoring would suggest additive information for detection of positive response to acetylcholine.