Improvement of exercise-induced ischaemia and myocardial perfusion after aminophylline

Previous studies have suggested that aminophylline improves exercise-induced ischaemia by preventing the redistribution of the coronary flow from ischaemic to non-ischaemic myocardium. The purpose of the study was to assess whether aminophylline improves myocardial perfusion in zones supplied by collateral circulation.

Twenty-three patients with an occluded coronary artery and collateral circulation from a non-diseased vessel underwent two symptom-limited exercise 99mTc-MIBI, single-photon emission computed tomography (SPECT) myocardial scintigraphy experiments, which were preceded by an intravenous infusion of either aminophylline (5 mg/kg over 20 min) or saline solution in a randomized double-blind control procedure. The MIBI SPECT images were analysed by two experienced observers who were blinded to each other's data.

All patients underwent cardiac catheterization. For 16 patients this was because of stable angina and the remaining eight were post-myocardial infarction patients with a positive exercise test. Aminophylline significantly increased the time to the onset of ischaemia in the 15 patients with a positive exercise test (mean +/- SD, 6.5 +/- 1.9 compared with 5.3 +/- 1.8 min, P < 0.005); and ischaemia occurred at higher rate-pressure product (230 +/- 68 compared with 195 +/- 68 HB x mmHg, P < 0.03). After aminophylline, exercise ST-segment depression was 1.1 +/- 0.5 mV, compared with 1.5 +/- 0.8 mV after placebo (P < 0.01). All patients had perfusion defects that resolved partially or completely in the rest images. The imaging score was significantly lower after aminophylline infusion than after placebo (9.7 +/- 9 compared with 12.1 +/- 10, P < 0.01).

Aminophylline significantly delayed the time to onset of exercise-induced ischaemia and improved perfusion in zones supplied by collateral circulation. Aminophylline-like drugs may be useful in the treatment of selected patients with ischaemic heart disease.