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.
Yamada
S
S
Cardiovascular Division, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
Kuga
K
K
Yamaguchi
I
I
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