Predictors of Recurrent Atrial Fibrillation Using Mode Switch Quantification

BACKGROUND The efficacy of mode switching to predict atrial fibrillation has been established in the literature. There have been few studies investigating the incidence and clinical implication of mode switch episodes quantified from implantable cardioverter defibrillator and pacemaker interrogation. We sought to investigate the incidence of mode switch recurrence in patients with implantable cardioverter defibrillators and permanent pacemakers. METHODS Mode switch was defined as any occurrence documented during device interrogation after the date of implantation. Clinical predictors (age, gender, hypertension, diabetes, syncope, atrial fibrillation (AF)), and medications were analyzed to determine association with single and recurrent mode switch occurrences. RESULTS There were 21 patients experiencing a mode switch event, identified from a group of 54 patients (42 males; mean age 70 ± 12 years; mean follow-up 29.1 ± 22 months (3.4 - 81.4 months)). All but two patients were receiving medical therapy including beta blockers, statins, ace-inhibitors, and anti-arrhythmics. There were 21 subjects who experienced at least one mode switch during their follow-up and 33 subjects who never experienced a mode switch during their follow-up time. The median time to first mode switch from device implantation was 39.3 months. Risk factors individually associated with any mode switch episode included: diabetes (DM) (P < 0.04) and use of digitalis (P = 0.02). Subjects who had a history of DM were 5 times more likely to have at least one mode switch occurrence. There was a significantly higher rate of mode switch among patients who were diabetic than patients who were not (3.7 per follow-up month ± 5.3 vs. 0.98 per follow-up month ± 2.02; P = 0.02). There was a significantly higher rate of mode switch among patients who were on digitalis than those who were not (3.1 per follow-up month ± 4.3 vs. 0.73 per follow-up month ± 1.9; P = 0.02). CONCLUSION The main factors associated with any mode switch are having a history of diabetes and digitalis use. Those patients who are diabetics and those on digitalis may warrant closer observation and management for the development of atrial fibrillation.