Relation of prognosis in sick sinus syndrome to age, conduction defects and modes of permanent cardiac pacing

Abstract

A large population of sick sinus syndrome (SSS) patients was analyzed to determine whether age of patients, presence of conduction disturbances and mode of permanent pacing are related to the occurrence of supraventricular tachyarrhythmias, cerebral embolism and cardiac mortality. Three hundred thirty-nine patients permanently paced (135 AAI, 79 DDD, 125 VVI) because of SSS were followed for a mean period of 5 years (range 2 to 10). Patients were divided into 4 groups according to age (<70 or > 70 years) and the presence or absence of an associated conduction disturbance. Sixty-eight percent of VVI, 55% of AAI and 40.5% of DDD patients were > 70 years of age. In the VVI and DDD groups a conduction disturbance was present in 67 of 204 (33%) patients; conduction disturbances were more common in patients > 70 years old (46 of 111, 41%) than in those <70 years old (21 of 93, 22%). The Wenckebach threshold (>140 beats/min) remained unchanged during the follow-up period in 82% of AAI patients. In 9% of these patients, the Wenckebach threshold showed some degree of deterioration, but only in 2 patients was it <100 beats/min (1.5%). Spontaneous second-degree atrioventricular block was observed in 7 patients (5%); it disappeared in 6 of these patients when drug therapy was discontinued. The incidence of atrial fibrillation was higher in the VVI group (47%) than in the DDD (13%, p < 0.05) and the AAI (4%, p < 0.001) patients without conduction disturbance. It was still higher in VVI patients with conduction disturbance (44%) compared to that of DDD patients with conduction disturbance (11.5%, p < 0.01). A higher incidence of stable atrial fibrillation in the VVI group was also observed, regardless of age or conduction disturbance. Overall mortality rates were 30% in VVI, 16% in DDD and 13% in the AAI mode (p < 0.001). Cardiac mortality was significantly higher in the VVI group (13%) compared to that of the AAI group (3%) (p < 0.001) regardless of age. It was also higher in the VVI group >70 years old (15%) than in the DDD group > 70 years (p > 0.03). The presence of conduction disturbance did not influence cardiac mortality. The stroke mortality rates were 8% in the VVI, 2% in the AAI and 2.5% in the DDD group (difference not significant). The difference in stroke mortality became statistically significant in the subgroup of patients > 70 years old between the VVI (17%) and AAI (3%) modes (p < 0.001). Our data indicate that the AAI and DDD modes should always be preferred to the VVI mode in treatment of SSS, particularly in patients > 70 years of age.