Multiple morphologies of ventricular tachycardia assessed by implantable cardioverter-defibrillator electrograms in a patient with Chagas disease, successfully treated with catheter ablation: modern problems, old solutions

Abstract

A 60-year-old man with Chagas disease, implanted with an implantable cardioverter defibrillator (ICD), experienced electrical storm. The ICD-stored electrograms revealed several ventricular tachycardia (VT) episodes with two different morphologies, confirmed thereafter by surface electrocardiogram. Both VTs originated from two different re-entry circuits and were successfully ablated. This case highlights the usefulness of ICD electrograms in identifying two VTs as having different sites of origin. Analysis of implantable cardioverter-defibrillator electrograms (ICD-EG) showed that monomorphic ventricular tachycardia (VT) with different QRS morphologies during different episodes (multiple morphologies, MM) predicted higher mortality. 1 A 60-year-old man implanted with an ICD (Medtronic Maximo-VR7232) for secondary prevention of death, with Chagas disease and left ventricular ejection fraction (LVEF), 0.45 was hospitalized for electrical storm. The ICD interrogation revealed 62 episodes of monomorphic VT. Analysing ICD-EG, a difference in morphology was seen only in the HVA/HVB electrogram (a QS complex in Figure 1A; a Qr complex in Figure 1B). During hospitalization he experienced several VT episodes and surface-electrocardiogram Figure 1 Schematic representation of the endocardial surface of the left ventricle. (A) and (B) Implantable cardioverter defibrillator- stored electrograms showing two different morphologies of the HVA/HVB electrogram. Note that this difference is not evident in the Vtip-Vring electrogram. (C) and (D) Twelve-lead surface electrocardiogram from two different spontaneous episodes of monomorphic ventricular tachycardia. (E) and (F) Surface and endocardial recordings from the two ventricular tachycardias induced at electrophysio- logicalstudy.NotethatQRSconfigurationsofinducedventriculartachycardiasmatchthoseofthespontaneousventriculartachycardias. There is a mismatch in lead V6 from ventricular tachycardia 1, probably due to different electrode position.