What is the role of radiofrequency ablation (RFA) in the treatment of ventricular tachycardia (VT)?

Updated: Dec 05, 2017
  • Author: Steven J Compton, MD, FACC, FACP, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Radiofrequency ablation (RFA) via endocardial or epicardial catheter placement can be used to treat ventricular tachycardia (VT) in patients with left ventricular dysfunction from previous myocardial infarction (MI), [66] cardiomyopathy, bundle-branch reentry, and various forms of idiopathic VT (see the image below). [40]  RFA is often used in conjunction with implantable cardioverter-defibrillator (ICD) therapy in the presence of recurrent VT episodes to reduce the frequency of required ICD therapies. [40] For patients with structural heart disease, it is currently uncertain whether VT ablation obviates other therapies, such as placement of an ICD). [5, 6, 7, 8]

Curative ablation of ventricular tachycardia (VT). Curative ablation of ventricular tachycardia (VT). The patient had VT in the setting of ischemic cardiomyopathy. VT was induced in an electrophysiology laboratory, and an ablation catheter was placed at the critical zone of slow conduction within the VT circuit. Radiofrequency (RF) energy was applied to tissue through the catheter tip, and VT was terminated when the critical conducting tissue was destroyed.

Current techniques include three-dimensional scar, late potential, and activation mapping, followed by high-energy RFA with irrigated-tip catheters capable of creating deeper lesions in the thicker left ventricular wall. In some patients, percutaneous epicardial ablation can be used successfully when endocardial lesions fail. [67, 68]

Catheter ablation is used early in patients with idiopathic monomorphic VT (ie, VT in a structurally normal heart arising from a focal source) that is resistant to drug therapy, as well as in those who are drug-intolerant or do not wish to have long-term drug therapy. [40] In these patients, ablation is used to treat symptoms rather than to reduce the risk of sudden death. In patients with structurally normal hearts, catheter ablation can eliminate symptomatic VT arising from the right or left ventricle.

Catheter ablation may also be used in patients with cardiomyopathy. The goal in these cases is to reduce the arrhythmia burden and thereby minimize the number of ICD shocks.

Ablation is also used in patients with bundle-branch reentrant VT. [40] Most ischemic reentrant VT requires a slow conduction zone, which is usually located along the border of a scarred zone of myocardium. The small physical size of the slow conduction zone makes it an ideal target for focal ablation procedures. Cell disruption can be achieved by using RFA or cryoablation via transvenous catheters during closed-chest procedures.

Kumar et al assessed the long-term prognosis after ablation for sustained VT in 695 consecutive patients with no structural heart disease (no SHD, n = 98), ischemic cardiomyopathy (ICM, n = 358), or nonischemic cardiomyopathy (NICM, n = 239). At a median follow-up of 6 years, ventricular arrhythmia (VA)-free survival was highest in patients with no SHD (77%), followed by patients with ICM (54%) and patients with NICM (38%); overall survival was highest in patients with no SHD (100%), followed by patients with NICM (74%) and patients with ICM (48%). [69]

In a study of 2061 patients with scar-related VT, Tung et al found that patients who experience no VT recurrence after catheter ablation have an increased rate of transplant-free survival. [70]  The investigators determined that following ablation, 70% of the study’s patients, who suffered from ischemic or nonischemic cardiomyopathy, were free from VT recurrence for 1 year, with 90% cardiac transplantation-free survival  at 1 year in those without VT recurrence, compared with 71% in patients with recurrence. [70]

In a two-center study that examined the use of a percutaneous left ventricular assist device (pLVAD) in patients undergoing ablation for scar-related VT, use of a pLVAD allowed maintenance in VT for a significantly longer period by virtue of its ability to maintain end-organ perfusion. [71]  Whether this effect will translate into clinical benefits is unclear. At the least, however, this study demonstrates the benefit of pLVADs in patients with scar-related unstable VT.

Because patients with ischemic VT often have multiple reentrant circuits, ablation is typically used as an adjunct to ICD therapy. If VT arises from an automatic focus, the focus can be targeted for ablation.

In patients with structurally normal hearts, the most common form of VT arises from the right ventricular outflow tract (RVOT). The typical outflow tract ectopic beat shows a positive QRS axis in the inferior leads. Abnormal or triggered automaticity is the most likely mechanism, and focal ablation is curative in these patients. Ablation cure rates typically exceed 95% if the arrhythmia can be induced in the electrophysiology laboratory. Difficulty of outflow tract ablation may be predicted by ECG morphology. [72]

Reentrant tachycardia may arise from the RVOT in patients with right ventricular dysplasia or repaired tetralogy of Fallot. These circuits are usually amenable to catheter ablation (see the image below). [73, 74]

Posteroanterior view of a right ventricular endoca Posteroanterior view of a right ventricular endocardial activation map during ventricular tachycardia in a patient with a previous septal myocardial infarction. The earliest activation is recorded in red, and late activation as blue to magenta. Fragmented low-amplitude diastolic local electrograms were recorded adjacent to the earliest (red) breakout area, and local ablation in this scarred zone (red dots) resulted in termination and noninducibility of this previously incessant arrhythmia.

In a study that evaluated the long-term safety and effectiveness of irrigated radiofrequency catheter ablation in 249 patients with sustained monomorphic VT associated with coronary disease, 75.9% achieved noninducibility of targeted VT. [75] The results showed that RFA reduced ICD shocks and VT episodes and improved quality of life at 6 months; improved long-term outcomes included a steady 3-year nonrecurrence rate with reduced amiodarone use and hospitalizations. [75]

In a prospective study to assess the incidence and predictors of major complications from contemporary catheter ablation procedures, major complication rates ranged from 0.8% (SVT) to 6% (VT associated with structural heart disease), depending on the ablation procedure performed. [76]  Renal insufficiency was the only independent predictor of a major complication.

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