Published Online
on December 11, 2009

A more recent version of this article appeared on February 1, 2010

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Original Article

ECG Criteria to Identify Epicardial Ventricular Tachycardia in Non-Ischemic Cardiomyopathy

Ermengol Vallès¹; Victor Bazan¹ and Francis E. Marchlinski^2,3

¹ Univ of Pennsylvania, Philadelphia, PA & Univ Autònoma de Barcelona, Barcelona, Spain;
² University of Pennsylvania, Philadelphia, PA

^* Corresponding author; email: francis.marchlinski{at}uphs.upenn.edu

Background—ECG criteria identifying epicardial (EPI) origin for ventricular tachycardia (VT) in non-ischemic cardiomyopathy (NICM) have not been determined. Endocardial (ENDO) and EPI basal left ventricle fibrosis characterizes the VT substrate.

Methods and Results—We assessed the QRS from 102 basal-superior/lateral EPI and 67 comparable ENDO pacemaps (PM) in 14 patients with NICM. Pacemapping focused on low bipolar voltage areas. Published morphology: q wave in lead I (QWL1), no q waves in inferior leads and interval criteria: pseudo-delta wave (PdW) 34ms, intrinsicoid deflection time 85ms, shortest RS complex 121ms and maximum deflection index (MDI) 0.55 were assessed for ability to identify EPI origin. Sixteen EPI and 8 ENDO of the 34 mapped VTs (71%) in the study population and 14 EPI and 7 ENDO VTs from an 11 patient validation cohort were localized to basal-superior/lateral left ventricle and corroborated pacing data. A QWL1 was seen in EPI but not ENDO PMs (91% vs 4%; p<0.001), identified 14/16 EPI VTs (sensitivity 88%) and was seen in 1/8 ENDO VT's (specificity 88%). None of the remaining criteria achieved similar sensitivity without specificity <50%. We identified 4 criteria (q waves in inferior leads, PdW 75 ms, MDI 0.59 and QWL1) having 95% specificity and 20% sensitivity in identifying EPI/ENDO origin for PMs. This four-step algorithm identified the origin in 109/115 PMs (95%), 21/24 VTs (88%) in study population and 19/21 VTs (90%) in validation cohort.

Conclusion—Morphologic ECG features that describe the initial QRS vector can help identify basal-superior/lateral EPI VTs in NICM.

Key Words: epicardial • ECG criteria • non-ischemic cardiomiopathy • ventricular tachycardia