Hyperdynamic Myocardial Response to Beta-Adrenergic Stimulation in Patients With Chest Pain and Normal Coronary Arteries Original Research Article

Objectives The goal of this study was to test the hypothesis that an abnormal response to beta-adrenergic stimulation may play a role in the pathophysiology of chest pain in patients with normal coronary arteries. Background The mechanism of angina-like (AL) chest pain in patients with angiographically normal coronary arteries remains controversial. Methods Fifty-eight patients with AL pain and a normal coronary angiogram underwent dobutamine echocardiography (DE) to evaluate regional wall motion and intraventricular flow velocities (IFV). Control patients consisted of 22 matched patients free of angina and coronary artery disease. Abnormal IFV were defined as dagger-shaped Doppler spectrum ≥3 m/s. Results Dobutamine-induced regional wall motion abnormalities did not develop in any of the patients. An IFV ≥ 3 m/s was found in 28 patients (48%) with AL pain but in only 4 (18%) control patients (p < 0.05). In the subgroup of patients with AL pain and IFV ≥3 m/s, plasma renin concentration (PRC) was higher as compared with those with IFV <3 m/s (18 ± 17 pg/ml vs. 9 ± 6 pg/ml, p < 0.05). There were no differences in plasma ADR, NADR, or angiotensin-converting enzyme levels. Fourteen patients with angina and IFV ≥3 underwent control DE and blood sampling after 6 weeks treatment with 10 mg of bisoprolol. In these patients, a decrease in IFV (from 3.4 ± 0.35 m/s to 2.46 ± 0.64 m/s, p < 0.001) and a decrease in angina score (from 5.4 ± 1.5 to 0.6 ± 1.4, p < 0.001) were observed at follow-up. Conclusions The present data suggest that an exaggerated myocardial response to beta-adrenergic stimulation plays a role in the mechanisms of chest pain in some patients with normal coronary arteries.