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QUARTERLY FOCUS ISSUE: HEART RHYTHM DISORDERS: CLINICAL RESEARCH

Electroanatomic Substrate and Ablation Outcome for Suspected Epicardial Ventricular Tachycardia in Left Ventricular Nonischemic Cardiomyopathy

Oscar Cano, MD^_*,, Mathew Hutchinson, MD^_*, David Lin, MD^_*, Fermin Garcia, MD^_*, Erica Zado, PA-C^_*, Rupa Bala, MD^_*, Michael Riley, MD, PhD^_*, Joshua Cooper, MD^_*, Sanjay Dixit, MD^_*, Edward Gerstenfeld, MD^_*, David Callans, MD^_* and Francis E. Marchlinski, MD^_*,_*

^_* Electrophysiology Section, Cardiovascular Division, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
Universitat Autònoma de Barcelona, Barcelona, Spain

Manuscript received February 9, 2009; revised manuscript received April 27, 2009, accepted May 5, 2009.

^_* Reprint requests and correspondence: Dr. Francis E. Marchlinski, 9 Founders Pavilion, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, Pennsylvania 19104 (Email: francis.marchlinski{at}uphs.upenn.edu).

Objectives: The aim of the study was to define the epicardial substrate and ablation outcome in patients with left ventricular nonischemic cardiomyopathy (NICM) and suspected epicardial ventricular tachycardia (VT).

Background: Ventricular tachycardia in NICM often originates from the epicardium.

Methods: Twenty-two patients with NICM underwent detailed endocardial and epicardial bipolar voltage maps and VT ablation for suspected epicardial VT. Eight patients with normal hearts and idiopathic VT served to define normal epicardial electrograms. Low-voltage regions were also assessed for wide (>80 ms), split, or late electrograms.

Results: Normal epicardial bipolar voltage was identified as >1.0 mV on the basis of the reference population. Confluent low-voltage areas were present in 18 epicardial (82%) and 12 endocardial (54%) maps and were typically over basal lateral LV. In the 18 patients with epicardial VT on the basis of activation/pacemapping, the mean epicardial area was greater than the endocardial low-voltage area (55.3 ± 33.5 cm² vs. 22.9 ± 32.4 cm², p < 0.01). Epicardial low-voltage areas showed 49.7% wide (>80 ms), split, and/or late electrograms rarely seen in the reference patients (2.3%). During follow-up of 18 ± 7 months, ablation resulted in VT elimination in 15 of 21 patients (71%) including 14 of 18 patients (78%) with epicardial VT.

Conclusions: In patients with NICM and VT of epicardial origin, the substrate is characterized by areas of basal LV epicardial > endocardial bipolar low voltage. The electrograms in these areas are not only small (<1.0 mV) but wide (>80 ms), split, and/or late, and help identify the substrate targeted for successful ablation.

Key Words: electroanatomical mapping • nonischemic cardiomyopathy • ventricular tachycardia

Abbreviations and Acronyms   AV = atrioventricular   ECG = electrocardiogram   ICD = implantable cardioverter-defibrillator   LP = late potential   LV = left ventricle/ventricular   NICM = nonischemic cardiomyopathy   RF = radiofrequency   VT = ventricular tachycardia

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				K. Shivkumar and R. Tung Improving our understanding of epicardial ventricular tachycardia in nonischemic cardiomyopathy. J. Am. Coll. Cardiol., August 25, 2009; 54(9): 809 - 811. [Full Text] [PDF]