[Incidence of myocardial bridges after adrenergic stimulation and decreasing afterload in patients with angina pectoris, but normal coronary arteries].

The prevalence of myocardial bridging in patients with angina pectoris but normal coronary arteries was evaluated in 1780 patients who consecutively underwent coronary angiography. 62 patients (3.5%) were free of coronary atherosclerosis or other organic heart disease. In four of these patients systolic narrowing of the LAD was present. The other 58 patients received 0.2 mg nitroglycerin (NTG) intracoronarily and 30 micrograms/ml orciprenalin (ORC) intravenously up to a heart rate of 130/min. Repeated angiography revealed systolic compression of the LAD due to myocardial bridging (MB) in 40% (25 of 62). The length of MB raised from 1.4 +/- 0.9 cm to 2.1 +/- 1.1 cm (p < 0.001) after NTG and to 2.8 +/- 1.1 cm (p < 0.001) after ORC. Coronary luminal stenosis increased from 48 +/- 29% to 67 +/- 25% after NTG (p < 0.001) and to 83 +/- 18% (p < 0.001) after ORC. The prevalence of myocardial bridging in 40% of patients with stress-induced angina pectoris but normal coronary arteries is high. Nearly always coronary compression by myocardial bridging is only evident after adrenergic stimulation or after afterload reduction. Therefore, NTG and ORC are useful drugs to facilitate diagnosis of myocardial bridging by increasing coronary compression.