Human histopathology of substrate based linear radiofrequency catheter ablation to electrical storm in old inferior myocardial infarction.

A 62-year-old-male with old inferior myocardial infarction suffered from drug resistant electrical storms and frequent shocks from an implantable cardioverter defibrillator. Emergent radiofrequency catheter ablation was performed. The patient underwent substrate mapping that uses an electro-anatomical mapping system during sinus rhythm because of multiple QRS morphologies and hemodynamic instability during ventricle tachycardia. The electro-anatomical map revealed a massive low voltage zone (<0.4 mV on amplitude of bipolar voltages) in the inferior wall of the left ventricle. Several ablation lines were placed (1) around the low voltage zone and (2) traversing the low voltage zone. After the ablation, electrical storms were well suppressed. Three weeks later he died due to pneumonia. Postmortal evaluation specified sites in the low voltage zone on invital electro-anatomical mapping were well correlated to histopathological dense scar. The ablation produced coagulation necrosis up to a maximum depth of 4.2 mm.