Comparative effects of atrial and ventricular stimulation on morbidity and mortality in patients with sinus node disease

In patients with sinus node disease (SND) the VVI pacing seems an inappropriate mode of cardiac stimulation because of its potential hemodynamic and arrhythmic adverse effects. The AAI-DDD pacing, preferred because of a lower morbidity, might also determine higher survival. We examined retrospectively 2 groups of patients with SND respectively stimulated with VVI pacing (Group I:57 patients) and AAI (Group II:53 patients). The mean follow-up was 43 months for Group I and 50 for Group II: 10 (17.5%) patients in VVI group and 5 (9.4%) in AAI group died. During the follow-up in the VVI group 3 patients developed congestive heart failure and 10 chronic atrial fibrillation whereas 1 case of heart failure and 2 of atrial fibrillation have been recorded in AAI group. Moreover, 4 patients had embolic complications in Group I; 5 (9.4%) patients with VVI pacing were converted into sequential pacing owing to occurrence of II degree heart block. The statistical analysis was performed by chi 2 test for the comparison among the proportions of events (atrial fibrillation, congestive heart failure, embolic accidents) in the 2 groups: a significative higher morbidity (p less than 0.01) was recorded in VVI group. Survival also is higher in AAI patients but the survival rate difference, calculated with Mantel-Cox method, is not statistically significant. The findings of this study show that in SND the superiority of AAI pacing over VVI is statistically significant as regards morbidity and we have also noticed an evident but not statistically significant superiority as regards mortality.