Electroanatomic substrate mapping successfully correlated bipolar electrogram amplitudes of 0.5-1.5 mV with areas of intermediate fibrosis (21-79%), identifying them as target regions for VT ablation.
Case Report (n=1)
Does electroanatomic substrate mapping correlate with histopathological findings in a patient undergoing VT ablation for remote MI?
Electroanatomic mapping accurately identifies regions of intermediate fibrosis (0.5-1.5 mV) which serve as effective targets for VT ablation, with cooled-tip RF creating deep transmural lesions.
INTRODUCTION: Catheter ablation of ventricular tachycardia (VT) in remote myocardial infarction (MI) often requires excessive mapping procedures. Documentation of the electrical substrate via electrogram amplitude may help to identify regions of altered myocardium resembling exit areas of reentrant VTs. METHODS AND RESULTS: A patient with multiple symptomatic monomorphic VTs (biventricular ICD, remote MI) underwent electroanatomic substrate mapping (CARTOtrade mark) for VT ablation. Regions of scar (bipolar electrogram amplitudes or=1.5 mV), and "altered" myocardium (0.5-1.5 mV) were identified. Ablation was directed to regions with "altered" myocardium based on pace map correlation. After ablation the clinical VT did not reoccur. The patient died due to worsening of heart failure 7 days afterward. During postmortal evaluation specified sites of electroanatomic mapping were correlated to histopathological findings. Annotated scar areas were documented to consist of areas with massive fibrosis (>or=80% of mural composition). Ablations were found to span through regions with intermediate fibrosis (21-79%) mapped as "altered" myocardium. Ablation produced transmural coagulation necrosis of mesh-like fibrotic tissue with interspersed remnants of myocardial cells up to a maximum depth of 7.0 mm. Subendocardial intramural bleedings were universal findings 7 days after ablation. CONCLUSIONS: Electroanatomic substrate mapping for VT ablation sufficiently identified regions of scar and normal myocardium. Regions with bipolar electrogram amplitudes between 0.5 and 1.5 mV were found to correlate to areas of "intermediate" fibrosis (21-79%) with only remnant strands of myocardial cells and were identified as target region for ablation. Cooled-tip endocardial radiofrequency ablation lead to transmural coagulation necrosis up to a depth of 7.0 mm.
Deneke et al. (Wed,) conducted a case report in Ventricular tachycardia in remote myocardial infarction (n=1). Electroanatomic substrate mapping and cooled-tip radiofrequency ablation was evaluated on Histopathological correlation of electroanatomic mapping sites. Electroanatomic substrate mapping successfully correlated bipolar electrogram amplitudes of 0.5-1.5 mV with areas of intermediate fibrosis (21-79%), identifying them as target regions for VT ablation.