Lower threshold for adenosine-induced chest pain in patients with angina and normal coronary angiograms.

OBJECTIVE To investigate whether patients with angina-like chest pain and normal coronary angiograms are more sensitive to adenosine as an inducer of chest pain. DESIGN Increasing doses of adenosine were given in a single blind study as intravenous bolus injections. Chest pain and the electrocardiographic findings were noted. PATIENTS Eight patients with angina-like chest pain but no coronary stenoses (group A), nine patients with angina and coronary stenoses (group B), and 16 healthy volunteers (group C). RESULTS In the absence of ischaemic signs on the electrocardiogram adenosine provoked angina-like pain in all patients in groups A and B. The pain was located in the chest, and its quality and location were described as being no different from the patient's habitual angina. In group C, 14 of 16 subjects reported chest pain. The lowest dose resulting in chest pain was lower in group A (0.9 (0.6) mg) than in group B (3.1 (1.5)mg) (p < 0.005) and in group C (6.2 (3.7) mg) (p < 0.005). The maximum tolerable dose was lower in group A (4.7 (2.1) mg) than in group B (9.2 (3.8) mg) (p < 0.05) and in group C (12.0 (4.1) mg) (p < 0.005). CONCLUSIONS Patients with angina-like chest pain and normal coronary angiograms have a low pain threshold and low tolerance to pain induced by adenosine.