EFFICACY AND PROARRHYTHMIA WITH THE USE OF D,L-SOTALOL FOR SUSTAINED VENTRICULAR TACHYARRHYTHMIAS

This study prospectively evaluated the clinical efficacy, the incidenc e of torsades de pointes, and the presumable risk factors for torsades de pointes in patients treated with d,l-sotalol for sustained ventric ular tachyarrhythmias. Eighty-one consecutive patients (54 with corona ry artery disease, and 20 with dilated cardiomyopathy) with inducible sustained ventricular tachycardia or ventricular fibrillation received oral d,l-sotalol to prevent induction of the ventricular tachyarrhyth mia. During oral loading with d,l-sotalol, continuous electrocardiogra phic (ECG) monitoring was performed. Those patients in whom d,l-sotalo l prevented induction of ventricular tachycardia or ventricular fibril lation were discharged with the drug and followed up on an outpatient basis for 21 +/- 18 months. Induction of the ventricular tachyarrhythm ia was prevented by oral d,l-sotalol in 35 (43%) patients; the ventric ular tachyarrhythmia remained inducible in 40 (49%) patients; and two (2.5%) patients did not tolerate even 40 mg of d,l-sotalol once daily. Four (5%) patients had from torsades de pointes during the initial or al treatment with d,l-sotalol. Neither ECG [sinus-cycle length (SCL), QT or QTc interval, or U wave] nor clinical parameters identified pati ents at risk for torsades de pointes. However, the oral dose of d, I-s otalol was significantly lower in patients with torsades de pointes (2 00 +/- 46 vs. 328 +/- 53 mg/day; p = 0.0017). Risk factors associated with the development of torsades de pointes were the appearance of an U wave (p = 0.049), female gender (p = 0.015), and significant dose-co rrected changes of SCL, QT interval, and QTc interval (p < 0.05). Duri ng followup, seven (20%) patients had a nonfatal ventricular tachycard ia recurrence, and two (6%) patients died suddenly. One female patient with stable cardiac disease had recurrent torsades de pointes after 2 years of successful treatment with d,l-sotalol. Torsades de pointes o ccurred early during treatment even with low doses of oral d,l-sotalol . Pronounced changes in the surface ECG (cycle length, QT, and QTc) in relation to the dose of oral d,l-sotalol might identify a subgroup of patients with an increased risk for torsades de pointes. Other ECG pa rameters before the application of d,l-sotalol did not identify patien ts at increased risk for torsades de pointes. Recurrence rates of vent ricular tachyarrhythmias are high despite complete suppression of the arrhythmia during programmed stimulation. Therefore programmed electri cal stimulation in the case of d,l-sotalol seems to be of limited prog nostic value.