Acquired Long QT Syndrome after Acute Myocardial Infarction: A Rare but Potentially Fatal Entity
Acquired long QT syndrome is typically caused by medications, electrolyte disturbances, bradycardia, or catastrophic central nervous system events. We report a case of myocardial infarction–related acquired long QT syndrome in a 58-year-old woman that had no clear cause and progressed to torsades de pointes requiring treatment with isoproterenol and magnesium. Despite negative results of DNA testing against a known panel of genetic mutations and polymorphisms associated with long QT syndrome, the patient's family history of fatal cardiac disease suggests a predisposing genetic component. This report serves to remind clinicians of this potentially fatal ventricular arrhythmia after myocardial infarction.
A) Electrocardiogram (ECG) on admission shows a QT interval of 420 ms and corrected QT interval (QTc) of 509 ms. B) Telemetric ECG tracing on hospital day 2 shows polymorphic ventricular tachycardia (torsades de pointes). C) Six hours later, the ECG tracing shows a QT interval of 640 ms and QTc of 757 ms.
Electrocardiogram on day of discharge (hospital day 6) shows a QT interval of 360 ms and QTc of 461 ms.
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