Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction

OBJECTIVES We sought to evaluate feasibility, safety and results of transthoracic epicardial catheter ablation in patients with ventricular tachycardia occurring late after an inferior wall myocardial infarction. BACKGROUND Transthoracic epicardial catheter ablation effectively controls recurrent ventricular tachycardia (VT) in patients with Chagas’ disease in whom epicardial circuits predominate. Epicardial circuits also occur in postinfarction VT. METHODS Fourteen consecutive patients aged 53.6 ± 14.5 years with postinfarction VT related to the inferior wall were studied. The VT cycle length was 412 ± 51 ms. Two patients had previously undergone unsuccessful standard endocardial radiofrequency energy (RF) ablation. The VT was incessant in one patient. Left ventricular angiography showed inferior akinesia in 13 patients and an inferior aneurysm in 1 patient. Ablation was performed with a regular steerable catheter placed into the pericardial sac by pericardial puncture. RESULTS The pericardial space was reached in all patients. Electrophysiologic evidence of an epicardial circuit was present in 7 of 30 VTs. Due to a high stimulation threshold, empirical thermal mapping was the only criterion used to select the site for ablation. Three VTs were interrupted during the first RF pulse. Two pulses were necessary to render it noninducible in 3 patients (1 VT per patient). In the remaining 4 VTs, 3, 3, 4 and 5 RF pulses, respectively, were used. The overall success was 37.14% (95% confidence interval, 11.83% to 62.45%). Patients are asymptomatic for 14 ± 2 months. CONCLUSIONS Postinfarction pericardial adherence does not preclude epicardial mapping and ablation to control VT related to an epicardial circuit in postinferior wall myocardial infarction.