A 40-year-old man who smoked with a self-described heart valve problem presented to the emergency department with acute onset of palpitations and diaphoresis, preceded by several days of flulike symptoms. He was afebrile and alert, with a blood pressure of 98/62 mm Hg. The electrocardiogram showed a wide-complex tachycardia at a rate of 218/min (Figure 1A) with right bundle branch block (RBBB) morphologic features and northwest frontal axis. The Brugada and Josephson signs were positive. There was evidence of fusion beats with intermediate QRS morphologic features and width (first and 17th beats along lead II).