Objectives: We investigated the effect of aminophylline, an antagonist of the adenosine P1 receptor, on cardiac pain experienced during percutaneous transluminal coronary angioplasty (PTCA).
Background: Adenosine may mediate cardiac pain because the administration of adenosine provokes cardiac pain like angina. However, it is not known whether endogenous adenosine released during myocardial ischemia is responsible for cardiac pain.
Methods: This was a single-blind, placebo-controlled randomized study. Of 21 men with stable effort angina with one-vessel coronary artery disease who underwent balloon inflation four times during PTCA, 11 received intravenously administered aminophylline before the fourth balloon inflation and the other 10 were given saline solution. The severity of cardiac pain based on the pain score and ST segment elevation on standard surface and intracoronary electrocardiograms were assessed.
Results: All patients experienced cardiac pain during balloon inflation. Aminophylline significantly prolonged the duration of both the symptom-free interval (from 42 +/- 13 to 64 +/- 27 s, mean +/- SD, p < 0.05) and inflation time (from 79 +/- 23 to 103 +/- 20 s, p < 0.05), and it significantly reduced the pain score from 7.6 +/- 1.4 to 4.6 +/- 2.3 (p < 0.01). However, aminophylline did not affect ST segment elevation. Saline solution did not affect any of these variables. Balloon diameter and pressure were not different between the third and the fourth inflation in either group.
Conclusions: Aminophylline significantly reduced the severity of cardiac pain during PTCA without affecting ST segment elevation. These findings suggest that the activation of P1 receptors by endogenous adenosine may be partially responsible for cardiac pain during ischemia.