798-4 Predictors of the Efficacy of Sotalol, a Class III Antiarrhythmic Agent, in the Treatment of Atrial Arrhythmias

Abstract

Sotalol, a class III antiarrhythmic drug (AAD) approved for use in ventricular arrhythmias, is being used with increasing frequency for supraventricular arrhythmias (SVA). To determine the efficacy of sotalol in the treatment of SVA and the predictors of sotalol failure or intolerance, 114 pts in whom Sotalol was begun for SVA were reviewed. All pts had atrial fibrillation (109) and/or atrial flutter (32) (AF: paroxysmal in 76, chronic in 35), except for 3 who had SVT. Mean duration after diagnosis of SVA was 5.2 ± 8.2 yrs. The mean number of priorfailed AADs was 1.96 ± 1.27 (range 0–6). Electrical cardioversion was achieved in 38/41 pts; 18 pts pharmacologically converted. Sotalol was stopped prior to discharge in 16 pts (inefficacy in 8, side effects in 4, prolonged QT in 2, and no longer indicated in 2). Prior to discharge, proarrhythmia occurred in 1 pt and bradycardia in 15 pts. 26 pts had prior pacemakers, and 11 pts required pacemakers for sotalol. Mean discharge dose was 229 ± 78 mg/day and mean discharge QTc was 462 ± 59 ms. Predictors for discontinuation of sotalol prior to discharge included degree of left atrial enlargement (LAE, p = 0.03) and QTc on sotalol (p = 0.063). Of 88 pts discharged on sotalol in sinus rhythm, 52 developed recurrent SVA (mean f/u 7.8 mos). After dose changes, 3 more pts became recurrence free. Of 36 recurrence-free pts, 12 had sotalol discontinued (side effects in 7, no longer indicated in 5). 2 pts discharged on sotalol developed proarrhythmia, and 2 pts died (1 noncardiac and 1 CVA). Overall, 27/114 pts (23.6%) begun on sotalol remained recurrence free and on the drug. Of 10 pts who began sotalol as first line antiarrhythmic therapy, 2 stopped sotalol in the hospital, 2 after hospital discharge, and 2 recurred after discharge (overall 40% recurrence free on sotalol). Univariate predictors of recurrent SVA on sotalol for pts discharged in NSR included younger age (60 ± 13 vs 68 ± 9 yrs, p = 0.001), longer duration since diagnosis of SVA (7.7 ± 11 vs 2.8 ± 4.0 yrs, p = 0.009), prior CABG (p = 0.01), number of failed AADs (2.4 ± 1.3 vs 1.4 ± 1.1, p = 0.0003), and shorter baseline QTc (441 ± 46 vs 465 ± 59 ms, p = 0.049) and discharge QRS (109 ± 32 vs 128 ± 41 ms, p = 0.025). Changes in HR or QTc were not significant predictors of sotalol success. Significant multivariate predictors of SVA recurrence adjusted for the follow-up period included number of failed AADs (p = 0.0024), discharge QRS (p = 0.0038) and age (p = 0.03). In summary, sotalol showed moderate (24%) efficacy in pts previously refractory to AADs and comparable efficacy as a first-line agent to that reported with other AADs. Changes in QT interval or HR could not be used to predict long term efficacy.