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This report presents a patient with macrovolt T wave alternans, PVC with R on T or a long-short sequence followed by torsades de pointes.
A 35-year-old female was referred to our hospital due to an episode of syncope in the sitting position. This episode was preceded by palpitation and happened two hours prior to our evaluation. There was no history of previous medical problems or drug usage and her physical examination was completely normal. Figure 1 illustrates the 12-lead ECG taken in the emergency room. A few minutes later, she again briefly lost consciousness and recovered spontaneously. Figure 2 demonstrates the rhythm strip recorded by cardiac monitoring during this second syncopal episode.
The ECG in Figure 1 shows normal QRS axis, PR and QRS interval, QTc of 540 msec, and macrovolt T wave alternans best seen in leads I, aVR and V1 [1,2]. There was no precipitant for prolongation of QT interval. Macrovolt T-wave alternans is a harbinger of electrical instability in congenital LQTS, although it could be seen in acquired LQTS . Figure 2 shows a long QT interval and polymorphic ventricular tachycardia (torsades de pointes) that began after a long-short sequence . Two important points regarding this tachyarrhythmia are it's association with macrovolt T wave alternans in the setting of a prolong QT interval and its initiation by a long-short sequence or a PVC during the vulnerable period of the T wave (R on T) . She was managed by implantation of implantable cardioverter-defirillator (ICD) and up titration of propranolol to 40 mg three times a day.