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 atrioventricular conduction disturbances. Resting electrocardiogram, 24-h Holler recording and treadmill test were performed in 17 patients with chronic atrial fibrillation and a slow ventricular response not related to drugs (age: 75±8 years). Then slowrelease theophylline was administered (700 mg 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<0.01), mean 24-h heart rate (51±6 versus 68±14 beats.min-1, P<0.01) and minimal 24-h heart rate (32±6 versus 42±11 beats.min-1, P<0.01). Cardiac pauses > 2.5 s were present in 13 patients during control recording; after theophylline they disappeared in 11 and markedly decreased in the remaining two. The longest R-R interval decreased in all patients (3218±943 versus 2121±518 ms, P<0.01). The daily number of wide QRS complexes increased in 16 out of 17 patients (428±752 versus 1146±1464 ms, P<0.01). Exercise heart rate, evaluated at the end of first and second stage, was higher after theophylline than during control test (P<0.01). These data suggest that oral theophylline can represent a valid therapy in most patients with atrial fibrillation and a slow ventricular response. © 1991 The European Society of Cardiology.