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

Abstract

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.

Keywords: Cardiac mapping; Case report; Catheter ablation; Myocardial infarction; Right ventricular infarction; Ventricular tachycardia.

Figure 1

Twelve-lead electrocardiogram of the clinical ventricular tachycardia at 210 b.p.m., left bundle branch block morphology and left superior axis deviation.

Figure 2

Left and right ventricular electroanatomic bipolar voltage maps showing the presence of two areas of abnormal substrate (electrogram amplitude <1.5 mV, coded with colours from blue to red). The left ventricular scar is located at the basal aspect of the posterior and postero-septal wall, while the right ventricular scar extends from the antero-lateral to the posterior aspect of the mid-basal free wall. LV, left ventricle; RV, right ventricle.

Figure 3

(A) Examples of late potentials (arrows) with different activation times recorded within the right ventricular free-wall abnormal substrate. (B) Isochronal late activation map (3 ms difference between isochrones) of the right ventricle in sinus rhythm. A centripetal gradient of delayed activation (colour range from red to purple) is evident within the abnormal voltage area. (C) Twelve-lead electrocardiogram recordings during pace-mapping. Pacing at sites showing late potentials (orange dot in B) results in paced-QRS morphologies matching those of the induced ventricular tachycardia in 12/12 electrocardiogram leads with a long stimulus-to-QRS latency (135 ms). (D) Ablation lesions (red and pink dots) deployed within and at the borders of the right ventricular scar.