Differentiation of arrhythmia originating from the right or left ventricular outflow tract based on the QRS morphology of premature ventricular beats and duration of repolarisation.

Background: Premature ventricular beats (PVBs) and monomorphic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) are the most frequent forms of idiopathic ventricular arrhythmias, but arrhythmia originating from the left ventricular outflow tract (LVOT) may be found in about 10% of these patients.

Aim: To compare electrocardiographic (ECG) patterns and duration of repolarisation after PVBs originating from the left and right superior part of the interventricular septum which were successfully treated with radiofrequency catheter ablation.

Methods: We studied 62 patients who did not receive antiarrhythmic drug treatment before ablation, including 50 patients with RVOT arrhythmia (21 males, mean age 42 ± 14 years, left ventricular ejection fraction [LVEF] 61 ± 6%) and 12 patients with LVOT arrhythmia (3 males, mean age 41 ± 17 years, LVEF 59 ± 9%).