Background Ventricular tachycardia (VT) in patients with chronic chagasic cardiomyopathy (CCC) is associated with considerable morbidity and mortality. Catheter ablation of VT in patients with CCC is very complex and challenging. The main goal of this work was to assess the efficacy of VT catheter ablation guided by late potentials (LPs) in patients with CCC. Methods and Results Seventeen consecutive patients with refractory VT and CCC were prospectively included in the study. Combined endo‐epicardial voltage and late activation mapping were obtained during baseline rhythm to define scarred and LP areas, respectively. The end point of the ablation procedure was the elimination of all identified LPs. Epicardial and endocardial dense scars (<0.5 mV) were detected in 17/17 and 15/17 patients, respectively. LPs were detected in the epicardial scars of 16/17 patients and in the endocardial scars of 14/15 patients. A total of 63 VTs were induced in 17 patients; 22/63 (33%) were stable and entrained, presenting LPs recorded in the isthmus sites. The end point of ablation was achieved in 15 of 17 patients. Ablation was not completed in 2 patients because of cardiac tamponade or vicinity of the phrenic nerve and circumflex artery. Three patients (2 with unsuccessful ablation) had VT recurrence during follow‐up (39 months). Conclusions Endo‐epicardial LP mapping allows us to identify the putative isthmuses of different VTs and effectively perform catheter ablation in patients with CCC and drug‐refractory VTs.

This report describes the case of a woman with Chagas' cardiomyopathy with severe left ventricular dysfunction and persistent left superior vena cava who presented with episodes of syncope without prodromes and who was referred for cardiac resynchronization therapy. Despite this venous anomaly, electrodes were safely positioned in suitable locations. ( Level of Difficulty: Intermediate. )

Figure 3 Atypical atrioventricular nodal reentrant tachycardia alternating atrioventricular and ventriculoatrial block. A: An alternating infra-Hisian and upper common pathway (UCP) block at each every other cycle is shown. B: Green and red arrows represent fast and slow pathway activation, respectively. AVN 5 atrioventricular node; HB 5 His bundle; LCP 5 lower common pathway.

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