Bradyarrhythmia profile and associated diseases in 1,265 patients with cardiac pacing.

Twelve hundred and sixty-five patients with implanted cardiac pacemakers were reviewed for known associated conditions and for the resulting bradycardia patterns. The group bradyarrhythmia profile was AV block in 75%, sick sinus syndrome (SSS) in 21% and combined arrhythmias in 4%. Thyroid diseases and acquired valvular disease were frequently associated with AV block especially of the Wenckebach type. Sick sinus syndrome occurred significantly more frequently in women (28%) than in men (26%). Isolated bradyarrhythmias (i.e., with no associated disease) were 22% of the entire group with a 26% incidence of SSS and with a significant association with previous gastric resection, pernicious anemia, and malabsorption compared to the groups with other associated diseases. Degenerative cardiac lesions caused by malabsorption and undiagnosed hypothyroidism in elderly women may contribute to the group of apparently isolated bradyarrhythmias.