Signal-Averaged Electrocardiography as a Noninvasive Tool for Evaluating the Outcomes After Radiofrequency Catheter Ablation of Ventricular Tachycardia in Patients With Ischemic Heart Disease: Reassessment of an Old Tool

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Abstract

Background—

Inducibility of ventricular tachycardia (VT) has limited ability to predict recurrent VT after catheter ablation (CA). We sought to correlate the signal-averaged ECG (SAECG) with the endocardial scar characteristics in patients with ischemic VTs. We suggest that successful CA can result in normalization of the SAECG.

Methods and Results—

Fifty patients (42 male; aged 67±10 years, ejection fraction 34±12%) with ischemic VTs were prospectively enrolled. SAECG was performed before and after CA. Patients with at least 2 abnormal criteria (filtered QRS ≥114 ms; root mean square 40 <20 μV, and low-amplitude potentials 40 >38 ms) were defined as having positive SAECG. There was a linear correlation between endocardial scar area (<1.5 mV) and filtered QRS (r=0.414; P=0.003). CA resulted in normalization of the SAECG in 6 patients. In patients with filtered QRS ≤120 ms, 13 (40.6%) patients had normal SAECG after CA compared with 7 (21.9%) before ablation (P=0.034). Patients with normal or normalized SAECG after CA had better VT-free survival compared with those whose SAECG remained abnormal. Abnormal SAECG after CA was a predictor for VT recurrence: hazard ratio=3.64; P=0.039 for the overall population, and hazard ratio=5.80; P=0.022 for patients having QRS ≤120 ms.

Conclusions—

There is a significant correlation between the surface SAECG and endocardial scar size in patients with ischemic VTs. A successful CA can result in normalization of SAECG that is associated with more favorable long-term outcomes. SAECG can be useful to assess the procedural success of VT ablation.

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