The correct solution is number 3. The Figure shows a clearly prolonged QT interval in lead II, both at rest and in early and late recovery. Patients with type 1 long QT syndrome (LQTS1) have a significantly longer QTc interval in early recovery than those with type 2 long QT syndrome, and this difference disappears at about minute 4 of recovery.1 Thus, prolonged QTc interval at the start of recovery can specifically identify patients with LQTS1 (response 4 incorrect), whereas both genotypes have a prolonged QTc in late recovery.2 In the present case, the clinical diagnosis was confirmed after a mutation was found in the genetic study in exon 15 of the KCNQ1 gene (c.1760C > T p.T587M). No electrocardiographic or echocardiographic findings supported a diagnosis of right ventricular arrhythmogenic cardiomyopathy (response 1 incorrect). The bifid and irregular T waves present in the trace, which occasionally appear in long QT syndrome, should not be confused with nonconducted P waves (response 2 incorrect).

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