High-degree atrioventricular block during anti-arrhythmic drug treatment: use of a pacemaker with a bradycardia-detection algorithm to study the time course after drug withdrawal.

AIM This study examines the recurrence of high-degree atrioventricular block (AVB) during a follow-up period of 2 years in patients with restored AV node function after antiarrhythmic drug withdrawal at implantation of a pacemaker. METHODS Nine men and eight women (77 +/- 7 years) taking antiarrhythmic drugs (beta-receptor blockers in 15) and presenting with high-degree AVB were followed for 2 years after being taken off drugs upon receiving a permanent pacemaker with special bradycardia detection software. RESULTS At inclusion, surface ECG identified two subsets of patients: a QRS duration < 120 ms (n = 5) and those with a QRS duration > or =120 ms (n = 12). During the 2-year follow-up, progression to high-degree AVB occurred in these groups: 1/5 (20%) and 9/12 (75%) P < 0.05. Six patients had to be restarted on drugs, mostly beta-receptor blockers, due to atrial tachyarrhythmias: 3/5 and 3/12. In total, 16 patients (94%) either developed high-degree AVB needing pacing or atrial tachyarrhythmias requiring drug treatment. CONCLUSION Patients on beta-receptor blocking drugs and QRS width > or =120 ms developing high-degree AVB should be recommended a pacemaker without further investigation or observation.