[Usefulness of atrial vulnerability in predicting atrial fibrillation in patients with sick sinus syndrome treated...

Atrial fibrillation (AF) is common in patients with sick sinus syndrome (SSS) treated with dual-chamber pacing and it may complicate their management. This study was undertaken to establish the usefulness of atrial vulnerability (AV), determined by means of transesophageal electrophysiological study (TES), in predicting the risk of developing AF and in deciding the type and program of pacemaker (PM) to be implanted in patients with SSS.

AV was assessed preoperatively using TES in 81 consecutive patients with SSS. AV (AF > 1 min) was divided into "low threshold" (induction with burst < or = 300/min) and "high threshold" (induction with burst > or = 350 min or with incremental ramp). The PM was programmed to ensure constant atrial capture in all patients. Follow-up lasted three years. No patients received antiarrhythmic drugs.

AV was positive in 52% of patients (Group A) and negative in 48% of patients (Group B). A history of paroxysmal AF was present in 52% of patients in Group A and in 12% of patients in Group B. At follow-up, 38% of Group A and 2% of Group B patients had chronic AF. AV had sensitivity, specificity, positive predictive value (ppv) and negative predictive value (npv) of 94, 59, 38 and 97%, respectively. Thirty-eight percent of patients showed low threshold vulnerability, with sensitivity, specificity, ppv and npv of 87, 92, 87 and 93%, respectively. Sensitivity, specificity, ppv and pnv for history of AF were 93, 100, 98 and 84%, respectively. When the vulnerability threshold and the history of paroxysmal AF were considered together, the sensitivity, specificity, ppv and npv was 94, 100, 100 and 83%, respectively. Multivariate analysis was shown to be an independent predictive value only for history of AF (p = 0.0002).

AV determined by means of TES, especially with a low induction threshold, shows excellent sensitivity and specificity in evaluating the risk of chronic AF. It could be useful in patients with SSS undergoing cardiac pacing who have never had AF, thus allowing a more accurate choice of the type and program of PM to be implanted. Case histories of paroxysmal AF could represent useful criteria for selecting patients at a high risk of developing chronic AF.