Right ventricular radiofrequency ablation of ventricular tachycardia after myocardial infarction

CHARACTERIZATION OF THE RIGHT VENTRICULAR SUBSTRATE PARTICIPATING IN POST INFARCTION VENTRICULAR TACHYCARDIA

BACKGROUND

The right ventricle (RV) is uncommonly implicated in post-infarction ventricular tachycardia (VT). The prevalence and features of RV substrate participating in post-infarction VT are undefined.

OBJECTIVES

To characterize critical RV substrate (CRVS) involvement in patients with post-infarction VT.

METHODS

We retrospectively reviewed 1279 patients with post-infarction VT undergoing catheter ablation at our center from January 2000 through May 2020. Cases with CRVS defined by conclusive demonstration of participation in VT with activation, entrainment and/or pace mapping during sinus rhythm were identified.

RESULTS

CRVS was identified in 27/1279 (2.1%), age 65±13 years, 96% males, median LV EF 25%, 93% with LBBB morphology VT. CRVS was identified by RV activation and/or entrainment mapping (n=19) or by presence of low-voltage abnormal electrograms with excellent pace-map for the targeted VT and non-inducibility following ablation (n=8). VT termination during RV ablation occurred in 15 patients. After a median follow-up of 20 months (interquartile range 9-53 months) and a median of 2 procedures (interquartile range 1-3), 22/27 (80%) patients had no VT recurrence and 11 (41%) died.

CONCLUSION

The RV contains critical substrate elements of post-infarction VT in at least 2.1% of cases. RV mapping should be considered in cases where LV mapping fails to demonstrate adequate targets, particularly in patients with LBBB morphology VT.

Right ventricular free-wall scar: an exceptional source of post-infarction ventricular tachycardia. A case report

BACKGROUND

In patients with coronary artery disease, ventricular tachycardia (VT) is usually related to left ventricular (LV) post-infarction scars.

CASE SUMMARY

A case of a 78-year-old man with post-infarction VT originating from the right ventricular (RV) free wall is described. Following recurrent episodes of VT with left bundle branch block morphology and left superior axis deviation, a patient with prior myocardial infarction was submitted to catheter ablation. Two areas of abnormal bipolar electrograms were observed at 3D electroanatomical mapping: one located at the basal aspect of the posterior and postero-septal LV, and the other one extending from the antero-lateral to the posterior mid-basal RV free wall. Ventricular late potentials (LPs) were recorded within both scars, but only pacing from those located in the RV resulted in long stimulus-to-QRS latency and optimal pace-mapping. Accordingly, this substrate was deemed the culprit of the clinical VT. Radiofrequency catheter ablation aimed at eliminating all LPs recorded from both scars was effective in preventing VT recurrences at follow-up.

DISCUSSION

A post-infarction RV free-wall scar may exceptionally be responsible of VT occurrence. Right ventricular mapping should be considered in selected cases based on 12-lead electrocardiogram VT morphology and prior RV infarct.

Successful epicardial catheter ablation of a septal ventricular tachycardia after myocardial infarction

A 55-year-old man underwent catheter ablation of ventricular tachycardia (VT) after anterior myocardial infarction. Although electrophysiological study suggested that the VT originated from the septum, biventricular endocardial irrigated radiofrequency ablation failed to interrupt the VT. Epicardial ablation at the site located halfway between the lesions in the right and left ventricles via a pericardial approach eliminated the VT, suggesting that the VT likely originated from the top of the septum. When VTs originating from the upper septum are refractory to endocardial ablation, epicardial mapping and ablation may be considered because only that site may be accessible with an epicardial approach.

The right ventricular tachycardias

A variety of tachycardias originate from the right ventricle or use right ventricular structures as part of their circuit. They are characterized by a left bundle branch block pattern. Many of these tachycardias are relatively easy targets for radiofrequency catheter ablation. Ventricular tachycardia (VT) is the most common manifestation of arrhythmogenic right ventricular dysplasia, an often familial disease that can cause sudden death. Catheter ablation, antiarrhythmic drugs, or an implantable cardioverter-defibrillator may be used as therapy. Idiopathic right ventricular tachycardia has a benign course. It most often arises from the septal region of the right ventricular outflow tract. It commonly presents as nonsustained, repetitive monomorphic VT. The success rate of catheter ablation is greater than 90%. Bundle branch reentry occurs in patients with cardiomyopathy and His-Purkinje disease. It uses the right bundle branch anterogradely and the left bundle branch retrogradely. The QRS is very similar during VT and sinus rhythm. It can be cured by catheter ablation of the right bundle branch. VT seldom originates from the right ventricle in patients with coronary artery disease, idiopathic cardiomyopathy, or myocarditis. Atriofascicular (so-called Mahaim) fibers can sustain antidromic AV reentrant tachycardia. They represent an accessory AV node and His-Purkinje-like conduction system with atrial insertion in the right free wall near the tricuspid annulus and distal insertion directly into the right bundle branch. The accessory connection is ablated at the level of the tricuspid ring.

Radiofrequency catheter ablation for postinfarct ventricular tachycardia

Catheter mapping and radiofrequency ablation of postinfarct sustained ventricular tachycardia (VT) remain one of the greatest challenges for the electrophysiologist. Although there were no major breakthroughs during the past year, several refinements and clarifications of existing mapping criteria were published. In addition, initial reports appeared describing new mapping systems and ablation technologies that may significantly impact the way ablation studies are performed as well as the way in which they affect success rates. Uncertainties remain as to how effective catheter ablation will be as a longterm cure for this type of VT. For the foreseeable future, catheter ablation in postinfarct VT will remain adjunctive rather than primary therapy.