Key result
Epicardial origin of outflow tract arrhythmias can be identified by specific ECG criteria and successfully treated via the venous system or subxiphoid mapping when endocardial ablation fails.
This review highlights ECG criteria for identifying epicardial outflow tract arrhythmias and outlines stepwise ablation strategies, including coronary venous and subxiphoid approaches, for cases failing endocardial ablation.
ECG criteria may guide ablation in refractory outflow tract arrhythmias; leaves open prospective validation of stepwise strategies.
The right ventricle outflow tract (RVOT) is the most common site of origin of idiopathic ventricular arrhythmias. The typical outflow tract arrhythmias pattern on ECG is an inferior axis deviation and left bundle branch block when originated on the RVOT and right bundle branch block morphology when originated on the left ventricular outflow tract (LVOT). There are several ECG tricks for different locations of origin. An increased Maximum Deflection Index (MDI) suggests epicardial origin of arrhythmia. In general the result of ablation is very good, but sometimes there are difficult and unsuccessful procedures. The origin in the aortic cusps and epicardium are the reason for failure in some cases. When they are epicardial, the arrhythmias can be accessed by the venous system or by subxiphoid epicardial mapping.
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Scanavacca et al. (2015) conducted a review in Idiopathic ventricular arrhythmias. Catheter ablation and epicardial mapping was evaluated. Epicardial origin of outflow tract arrhythmias can be identified by specific ECG criteria and successfully treated via the venous system or subxiphoid mapping when endocardial ablation fails.
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