Abstract 14890: Hyponatremia Associated with Flecainide: Case Series
Introduction: Flecainide is a Class IC antiarrhythmic agent; its primary electrophysiologic effect is to block fast, inward sodium current, thereby prolonging the refractory period and slowing conduction in a wide range of cardiac tissues. It is used to prevent and treat cardiac arrhythmias. In the absence of cardiac side effects, flecainide is a well-tolerated agent. Flecainide-induced hyponatremia is not well-documented in the literature; a few case reports document the presence of hyponatremia with the use of flecainide. Its incidence is not reported.
Methods: We reviewed 663 consecutive patients (65 ± 15 years old, 41.9% males) who were admitted to our institution from 1995 to 2011 and received flecainide therapy. Incidence of drop in serum sodium was calculated. Any drop of serum sodium by 10 mEq/L after starting flecainide therapy was considered hyponatremia. Baseline demographics (age, gender, race), comorbidities (coronary artery disease, diabetes mellitus, low ejection fraction) and the use of diuretics were analyzed to evaluate the risk of developing hyponatremia with flecainide use. All-cause mortality was assessed. Mean follow-up was 29 months.
Results: Incidence of hyponatremia in this patient population was 8.9%. The average serum sodium level in patients who had hyponatremia was 127 ± 5 mEq/L. Incidence of hyponatremia was higher in women (10.9% vs. 6%, p=0.0324) and with age (<50: 1.9%, 50-64: 5.8%, 65-74: 7.4%, ≥75: 17.2%, p<0.001). Race did not affect incidence of hyponatremia. As expected, incidence increased with use of diuretics (11% vs. 2.9%, p=0.001). Elevated creatinine (15% vs. 3.9%, p<0.001) and presence of diabetes mellitus (13.6% vs. 7.2%, p=0.0118) were associated with higher incidence of hyponatremia. All-cause mortality was higher in patients on flecainide with decreased sodium level (35.6% vs. 10.9%, p<0.001). There was no difference in hyponatremia incidence in patients with history of coronary artery disease and ejection fraction <40%.
Conclusions: Incidence of serum sodium reduction with flecainide use during hospital stay in this patient population was 8.9%. Female gender, older age and concomitant use of diuretics are risk factors to increase this incidence.
- © 2012 by American Heart Association, Inc.