Dromotropic effects of oral theophylline in patients with atrial fibrillation and a slow ventricular response

Theophylline increases sinus rate, but as yet its use has not been investigated in patients with chronic atrio ventricular conduction disturbances. Resting electrocardiogram, 24-h Holter recording and treadmill test were performed in 17 patients with chronic atrialfibrillation and a slow ventricular response not related to drugs (age: 75±8 years). Then slow-release theophylline was administered (700mg daily) and after 5 days these investigations were repeated with the same methods. Theophylline increased mean resting heart rate (51±6 versus 67±13 beats.min−1, P