[Atrial rate and increased work capacity during DDD pacing in patients with a high level atrioventricular block]

Though the benefits of DDD pacing in patients with high-degree atrioventricular (AV) block are undisputable, it is desirable to identify--because of economic aspects--the subgroups of patients with maximum benefit from DDD pacing. An attempt has been made in the presented study to identify the subgroups of patients with a high increase in maximum working capacity during DDD pacing. The predictability of artificial pacemaker block based on atrial rate behaviour during exercise in heart block and VVI pacing has also been determined. The results are presented obtained in 26 patients with high-degree AV block and normal sinus function, who underwent exercise testing during AV block, VVI and DDD pacing. The benefit from DDD pacing in maximum working capacity was higher in patients with a lower resting atrial rate, steeper slope and a higher mean increase of atrial rate in the course of exercise during VVI pacing only. On the other hand, the maximum atrial rate during AV block is a good predictor of the incidence of artificial pacemaker block during exercise during DDD pacing and provides useful information for setting the upper rate limit of DDD pacemaker.