Maintenance of AAI(R) mode at the time of generator replacement

In isolated sinus node disease single lead atrial stimulation is recommended. However, an inherent risk includes emerging AV node disturbances with serious bradycardia in the follow-up. This possible scenario frequently results in the implantation of an additional ventricular lead. In this single-centre retrospective study the interval between 1982 and 2007 was analysed. During this period a total of 6,309 antibradycardia pacemakers were implanted for the first time. Ten percent (n=631) of these devices were single lead atrial pacemakers for treatment of the sick sinus syndrome (SSS). In these 26 years 136 pacemaker replacement operations were performed. During this procedure a thorough reevaluation of the stimulation mode was done. In 80.6% (n=112) AAI(R) was continued, in 10.1% (n=14) the system was upgraded to DDD(R), and in 9.3% the mode was changed to VVI(R). There were no significant differences in the lifetime of the AAI(R) pacemakers up to the time of this operation: 7.9 vs 6.3 vs 7.0 years. The single lead atrial pacing mode in SSS is mostly safe also in the long term. A premature change of stimulation mode is rarely necessary.