Morbidity and Mortality of Patients with Sinus Node Disease: Comparative Effects of Atrial and Ventricular Pacing

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Abstract
In patients with sinus node disease (SND), VVI pacing seems an inappropriate method of cardiac stimulation because of its potential adverse hemodynamic and arrhythmic effects. AAI-DDD pacing, preferred because of lower morbidity, may also determine a higher survival rate. We examined retrospectively two groups of patients with SND. Stimulated respectively with VVI pacing (group 1 = 57 patients) and AAI pacing (group 2 = 53 patients). The mean duration of the follow-up interval was 40.1 months for group 1 and 45 months for group 2. Ten patients (17.5%) in the VVI group and five (9.4%) in the AAI died. During the follow-up, in the VVI group three patients developed congestive heart failure and ten developed chronic atrial fibrillation, whereas only one case of heart failure and two with atrial fibrillation have been recorded in the AAI group. Moreover, four patients had embolic complications in group 1. Five patients (9.4%) with AAI pacing were converted to sequential pacing due to the occurrence of second-degree heart block. The statistical analysis was developed by the X2 test for the comparison of the proportion of the events (atrial fibrillation, congestive heart failure, embolic accidents) in the two groups: a significantly higher morbidity (P less than 0.01) was recorded in the AAI group. Survival is also higher in AAI patients, but the survival rate difference, calculated using the Mantel-Cox method, is not statistically significant. The findings of our study show that in SND the superiority of AAI pacing over VVI is statistically significant as far as morbidity is concerned, and we have also noticed an evident but not statistically significant superiority regarding mortality.