Torsade de pointes induced by intravenous and long-term oral amiodarone therapy in a patient with dilated cardiomyopathy.
A 70-year-old woman with dilated cardiomyopathy and ventricular tachyarrhythmia was initially treated in 1990 with intravenous amiodarone (240 mg). She developed a junctional escape rhythm (48 beats/min) with QT prolongation (QT: 0.68 s) and 8 h later developed torsade de pointes (TdP). Because other antiarrhythmic drugs did not suppress the arrhythmia, oral amiodarone (100 mg/day) was started in 1995, 7 weeks before she presented with congestive heart failure. The QT prolongation (QTc: 0.64) increased after administration of dopamine, and TdP again developed. This case suggests that amiodarone induces proarrhythmias by different mechanisms when administered intravenously or orally.
Cardiovascular Division, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
S
S
Yamada
K
K
Kuga
I
I
Yamaguchi
D000284:Administration, Oral; D000368:Aged; D000638:Amiodarone / Q000008:administration & dosage / Q000009:adverse effects*; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000009:adverse effects; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000188:drug therapy*; D004562:Electrocardiography; D017809:Fatal Outcome; D005260:Female; D006333:Heart Failure; D006801:Humans; D007275:Injections, Intravenous; D008133:Long QT Syndrome; D016171:Torsades de Pointes / Q000139:chemically induced* / Q000209:etiology
D000889:Anti-Arrhythmia Agents; D000638:Amiodarone