CHRONIC ATRIAL-FIBRILLATION AND STROKE IN PACED PATIENTS WITH SICK SINUS SYNDROME - RELEVANCE OF CLINICAL CHARACTERISTICS AND PACING MODALITIES

Background. The goal of the report was to study the long-term incidenc e and the independent predictors for chronic atrial fibrillation and s troke in 507 paced patients with sick sinus syndrome, adjusting for di fferences in baseline clinical variables with multivariate analysis. M ethods and Results. From 1980 to 1989, we implanted 376 dual-chamber, 19 atrial, and 112 ventricular pacemakers to treat patients with sick sinus syndrome. After a maximum follow-up of 134 months (mean: 59+/-38 months for chronic atrial fibrillation, 65+/-37 months for stroke), a ctuarial incidence of chronic atrial fibrillation was 7% at 1 year, 16 % at 5 years, and 28% at 10 years. Independent predictors for this eve nt, from Cox's proportional hazards model, were history of paroxysmal atrial fibrillation (P<.001; hazard ratio [HR] = 16.84), use of antiar rhythmic drugs before pacemaker implant (P<.001; HR=2.25), ventricular pacing mode (P=.003; HR=1.98), age (P=.005; HR=1.03), and valvular he art disease (P=.008; HR=2.05). For patients with preimplant history of paroxysmal atrial fibrillation, independent predictors were prolonged episodes of paroxysmal atrial fibrillation (P<.001; HR=2.56), long hi story of paroxysmal atrial fibrillation (P=.004; HR=2.05), ventricular pacing mode (P=.025; HR=1.69), use of antiarrhythmic drugs before pac emaker implant (P=.024; HR=1.71), and age (P=.04; HR=1.02). Actuarial incidence of stroke was 3% at 1 year, 5% at 5 years, and 13% at 10 yea rs. Independent predictors for stroke were history of cerebrovascular disease (P<.001; HR=5.22), ventricular pacing mode (P=.008; HR=2.61), and history of paroxysmal atrial fibrillation (P=.037; HR=2.81). Concl usions. Development of chronic atrial fibrillation and stroke in paced patients with sick sinus syndrome are strongly determined by clinical variables and secondarily by the pacing modality. Ventricular pacing mode predicts chronic atrial fibrillation in patients with preimplant paroxysmal atrial fibrillation but not in those without it.