A CASE-REPORT OF MYOLYSIS DURING HIGH-DOSE AMIODARONE THERAPY FOR UNCONTROLLED VENTRICULAR-TACHYCARDIA

We report a rare case of a 41-year-old male patient, a professional mu sician, with dilated cardiomyopathy and sustained ventricular tachycar dia (VT) that was refractory to class I antiarrhythmic drugs. Severe m yolysis developed after 10 months' administration of amiodarone (400 m g/day) in combination with mexiletine (300 mg/day) and disopyramide (4 00 mg/day). He had been suffering from severe moving muscle pain and a n extremely high (16,830 IU/ml) serum level of creatine kinase (CK). T he dosage of amiodarone was reduced from 400 mg/day to 200 mg/day with out reduction of mexiletine or disopyramide and the patient's symptoms diminished. However, sustained VT developed, and so the dosage of the drug was increased to 250 mg/day. The high serum level of CK also dec reased and returned to the normal range after the reduction in amiodar one dosage. Electrophysiologic examination of moving muscle revealed n ormal motor and sensory conduction velocities and, furthermore, the el ectromyogram revealed normal potentials and normal motor units. We con clude that severe myolysis developed as a result of the high dose and chronic administration of amiodarone. This is the first report of a Ja panese patient showing rare and serious adverse effects in response to amiodarone treatment.