Long-term survival of chosen atrial-based pacing modalities.

Atrial-based cardiac pacing modalities were chosen in 341 of 684 (50%) patients selected for permanent cardiac pacing at the Grey Nuns Community Health Center between 1989 and 1995. There were 183 males and 158 females. Mean age was 70 years (range 8-97 years). The indications for atrial-based pacing were: advanced atrioventricular (AV) block (n = 166) 49%; sick sinus syndrome (n = 153) 45%; hypersensitive carotid sinus syndrome (n = 11) 3%; neurocardiac syncope (n = 10) 2.9%; and hypertrophic cardiomyopathy (n = 1) 0.3%. Forty-eight patients had a known history of paroxysmal atrial arrhythmias. All patients had routine follow-up performed at 24 hours, 7 days, 6 weeks, 3 months, and then 6 biannually. Mean follow-up was 6.5 years (range 1 month to 12 years). Observed survival of the programmed atrial-based modality was compared to the original mode chosen at the time of implantation. Thirty-five of 37 (95%) chosen for AAIR modes remain programmed AAIR. Twenty-two of 24 (92%) chosen for VDDR modes remain programmed VDDR. Two hundred and fifty-five of 280 (91%) chosen for DDD or DDDR modes remain programmed DDDR. Two of 37 (5%) patients originally implanted with AAI pacing systems were upgraded to DDDR mode due to new onset AV block. One of 24 (4%) patients originally implanted with a VDDR pacing system was upgraded to DDDR due to loss of atrial sensing of the single pass lead. Twenty-six of 304 (8.5%) patients originally implanted with DDD/DDDR (n = 25) and VDDR (n = 1) pacing systems were reprogrammed to VVI or VVIR: 16 (62%) due to sustained refractory atrial arrhythmias; 5 (19%) due to atrial lead malfunction; and 5 (19%) due to reasons unrelated to the pacing system. With careful review of the patients' conduction disorder and appropriate selection of pacing modality, the observed survival of long-term atrial-based pacing remains at 92% when compared to the chosen modality at the time of implantation. Atrial-based pacing may be used to reduce the incidence of atrial dysrhythmia with careful programming of the base atrial pacing rates.