PHYSIOLOGICAL PACING IN THE BRADYCARDIA-T ACHYCARDIA SYNDROME

92 patients with a dual-chamber pacemaker implanted for symptomatic br adycardia and a history of paroxysmal atrial fibrillation were followe d for 1116 +/- 762 days. 25 patients (= 27.2%) had no further arrhythm ia, in 67 cases, the number of new episodes ranged between 1 and 11 (m = 2.9). With a medication of 1-9 antiarrhythmic drugs, the risk of ch ronic atrial fibrillation was 5% after one year and 26% after five yea rs, respectively. During ergometry using the CAEP protocol, 19 out of 27 patients exhibited chronotropic incompetence with a heart rate belo w 60 + 2 beats/min (bpm) per ml/kg/min of O2 consumption at half the m aximum workload reached. When patients were paced in the atrium at a r ate of 110 bpm during the test, 7 out of 23 developed second degree AV block. It is concluded that, within five years, roughly 75% of patien ts who are paced and medicated for the bradycardia-tachycardia syndrom e may preserve the atrial function of their pacing system which should offer the option of (additional) ventricular pacing and of rate-respo nsive therapy.