Idiopathic Ventricular Tachycardia: Transcatheter Ablation or Antiarrhythmic Drugs?

Abstract

Introduction: Ventricular tachycardia or frequent premature ventricular contractions (PVCs) can occur in the absence of any detectable structural heart disease. In this clinical setting, these arrhythmias are termed idiopathic. Usually, they carry a benign prognosis and any potential ablative intervention is carried out if patients are highly symptomatic or, more importantly, if frequent ventricular arrhythmias can lead to ventricular dysfunction.

Methods: In this paper, different forms of idiopathic ventricular tachycardia are reviewed. Outflow tract ventricular tachycardia from the right ventricle is the most frequent form of the so-called idiopathic ventricular tachycardia. Other forms of idiopathic ventricular arrhythmias include ventricular tachycardia/PVCs arising from tricuspid annulus, from the mitral annulus, inter-fascicular ventricular tachycardia and papillary muscle ventricular tachycardia. When interventional treatment is deemed necessary, detailed mapping ( earliest activation during VT/PVC, pace mapping ) is crucial as to identify the successful ablation site. Catheter ablation more than antiarrhythmic drug treatment is usually highly effective in eliminating idiopathic ventricular arrhythmias and providing prevention of recurrence.

Conclusions: Idiopathic VTs are not considered life-threatening arrhythmias and, prevention of recurrences is often achieved by means of catheter ablation that provides an improvement of quality of life. The overall acute success rate of catheter ablation is about 85-90% with a long-term prevention of arrhythmia recurrence of about 75-80%. It is advisable that the procedure is carried out by electrophysiologists with expertise in VT catheter ablation and extensive knowledge of cardiac anatomy as to ensure a high success rate and reduce the likelihood of major complications.

Figure 1.. Centre: Example of substrate mapping (CARTO 3) and ablation sites at epicardial aspect of the right ventricular outflow tract (RVOT) in a patient highly symptomatic for frequent ventricular premature beats leading to reduced left ventricular function. Previous attempt to ablate from the endocardial site of the RVOT failed to eliminate the arrhythmia. Left End: green recordings: 3 surface EKG leads; white recordings: low amplitude bipolar and unipolar potentials before ablation which are beyond the QRS offset

Figure 2.. Snapshot showing the successful ablation site at the left coronary cusp. Above, Left end: Right anterior oblique view of 3-D activation map (Ensite NaV-X) of ventricular premature beat from the left coronary aortic cusp. Right end: Left anterior oblique view of the same activation map, showing the successful ablation site at the left coronary aortic cusp. Bottom: Intracavitary recordings showing earliest bipolar and unipolar potentials at the ablation catheter preceding the QRS onset of the ventricular premature beat. Please note the fragmentation at the ablation site, usual finding in this context