Macrovolt T-Wave Alternans and Polymorphic Ventricular Tachycardia

A previously healthy 18-year-old woman presented to her local hospital with 3 days of heart failure symptoms.An echocardiogram showed severe left ventricular dilation and global hypokinesis with an ejection fraction of 17%.Her history and clinical evaluation were consistent with an acute virus-induced cardiomyopathy.She had not taken any medications before her presentation, and her initial ECG was normal.On hospital day 3, she had a cardiac arrest with documented torsade de pointes, and electric cardioversion was successful.Amiodarone was initiated, and she was transferred to our institution.As shown in the Figure , A, her admission ECG was notable for right-axis deviation, marked QT prolongation (QTc, 685 ms), and classic T-wave alternans.She subsequently developed multiple episodes of polymorphic ventricular tachycardia, as shown in the Figure , B. Amiodarone was discontinued as a result of prolongation of the QT interval.The patient eventually received a left ventricular assist device for hemodynamic support, and after her acute illness resolved her QT interval normalized, and there were no further arrhythmias.Beat-to-beat T-wave alternans is known to frequently precede the onset of malignant ventricular arrhythmias.