The effect of aminophylline infusion on the exercise capacity in patients with syndrome X

Aminophylline was known to decrease effort angina and ischaemia in patients with coronary artery disease and stable angina. This effect has been expla ined by the antagonization of the vasodilatation caused by adenosine and th e prevention of the transmural myocardial maldistribution (steal phenomenon ). In this study, treadmill exercise tests (with Bruce protocol) were performe d in 14 patients (11 women, 3 men, mean age 51 +/- 9.9 years) diagnosed wit h syndrome X (typical anginal chest pain, abnormal stress test, normal coro nary angiography) before (basal condition) and after the acute i.v, aminoph ylline infusion (total dosage 6 mg/kg within 15 minutes). It was shown that aminophylline lengthened the time before the occurrence o f ischaemia in patients with syndrome X by increasing the ischaemia thresho ld in spite of the occurrence of tachycardia but it had no effect on the to tal exercise duration. Aminophylline infusion also exerted a beneficial eff ect on exercise-induced chest pain. It has been suggested that the role of the adenosine receptor could be important in the pathogenesis of syndrome X .