Patients were followed every three months for assessment of secondary endpoints, to record therapies delivered by the ICD and potential adverse effects of the ICD, and to assess compliance and potential adverse symptoms in patients treated with antiarrhythmic drugs. A 12-lead electrocardiogram was obtained every six months, and appropriate laboratory and pulmonary tests were performed at six and eighteen months on patients receiving amiodarone. The average follow-up was expected to be 2.6 years. Analysis was done by intention-to-treat. The outcome of primary interest in the subrandomization between sotalol and amiodarone was the time to withdrawal from assigned therapy.