Idiopathic Polymorphic Ventricular Tachycardia: a “Benign Disease” with a Touch of Bad Luck?

Ventricular extrasystole originating from the right ventricular outflow tract or the left ventricular outflow tract are the most commonly encountered ventricular arrhythmias recorded in ostensibly healthy individuals with no evidence of heart disease. These ventricular arrhythmias have a distinctive electrocardiographic morphology. The morphology is so distinctive that it is common practice to accept the diagnosis of "idiopathic benign ventricular arrhythmias from the outflow tract" based on this unique morphology when the electrocardiogram during sinus rhythm and the echocardiogram are normal, sometimes removing the need to perform invasive tests in patients. Even if the outflow ventricular extrasystole ultimately triggers sustained ventricular arrhythmia, the resulting ventricular tachycardia (VT) will be a monomorphic VT originating from the outflow tract, which is known to be hemodynamically well tolerated. Thus, idiopathic ventricular arrhythmias originating from outflow tracts are universally considered benign. In 2005, we described a rare form of malignant polymorphic VT resulting in syncope or cardiac arrest. Here, we review the literature on this topic since the emergence of initial descriptions of this intriguing phenomenon.