The Effects of Oral Theophylline in Patients with Cardiac Syndrome X

Patients with cardiac syndrome X are affected by exertional angina, positive exercise test, normal coronary arteriogram. It seems that these people have an altered perception of cardiac pain, due to increased sensitivity to adenosine. Previous studies have shown that intravenous or oral aminophylline, an adenosine receptor blocker, improves exercise tolerance in patients with this disorder. In this study the effects of oral theophylline on clinical presentations and exercise test in patients with cardiac syndrome X referring to Cardiology clinic of Imam Khomeini hospital in Sari were studied during the year 2003. This study was a double-blind placebo controled clinical trial done on the patients with cardiac syndrome X. Twenty Patients (18 women and 2 men), mean age 50 years, with syndrome X were studied. Patients were randomly divided into two control and case groups, both of the groups had similar basic features. In the case group theophylline with the dose of 150 to 225mg (according to the age and cigarette smoking was given twice a day, and the control group received placebo for three weeks. All patients underwent treadmill exercise testing at the end of the three week period. The number of episodes of chest pain was recorded. Two paired student's t test was used for comparison of the obtained results. In this study the total exercise duration in the case group was longer than the control group (p<0.05), and the number of episodes of chest pain in the case group was less than the control group (p<0.05). There was no significant differences in the magnitude of ST segment at the peak of exercise and the time of angina at exercise test between the two groups. It seems that oral theophylline has a favorable effects on the control of the symptoms of cardiac syndrome X like the duration of exercise test and the number of episodes of chest pain, but its effects on the symptoms and ST segment changes need further studies.