Isolated septal substrate for ventricular tachycardia in nonischemic dilated cardiomyopathy: Incidence, characterization, and implications

Haris M. Haqqani, Cory M. Tschabrunn, Wendy S. Tzou, Sanjay Dixit, Joshua M. Cooper, Michael P. Riley, David Lin, Mathew D. Hutchinson, Fermin C. Garcia, Rupa Bala, Ralph J. Verdino, David J. Callans, Edward P. Gerstenfeld, Erica S. Zado, Francis E. Marchlinski

Research output: Contribution to journalArticlepeer-review

135 Scopus citations


Background: The substrate for ventricular tachycardia (VT) in nonischemic cardiomyopathy (NICM) has a predilection for the basolateral left ventricle with right bundle branch block VT morphology. Objective: The purpose of this study was to describe a unique group of NICM patients with septal VT substrate. Methods: Between 1999 and 2010, 31 (11.6%) of 266 patients with NICM undergoing VT ablation had septal substrate and no lateral involvement. Mean age was 59 ± 12 years, and ejection fraction was 30% ± 14%. Eight patients had heart block. Results: Cardiac magnetic resonance showed septal delayed enhancement in 8 of 9 patients. Electroanatomic mapping demonstrated bipolar low voltage (<1.5 mV) extending from the basal septum in 22 of 31 patients. The remaining 9 patients had normal endocardial bipolar voltage but abnormal unipolar septal voltage (<8.3 mV) consistent with intramural abnormalities. Epicardial mapping in 14 patients showed no scar in 9 and patchy basal left ventricular summit scar in 5. VTs were mapped to the septal substrate, with 62% having right bundle branch block morphology and V 2 precordial transition pattern break in 17% suggesting periseptal exit. After substrate and targeted VT ablation, no VT was inducible in 66% and no "clinical targeted" VT in 86%. Over a mean follow-up of 20 ± 28 months, VT recurred in 10 (32%) patients. Conclusion: Isolated septal VT substrate is uncommon in NICM. Biventricular low-voltage zones extending from the basal septum are characteristic, but septal scarring can be entirely intramural as evidenced by unipolar/bipolar electrograms and imaging. Multiple unmappable morphologies are the rule, often requiring several procedures aggressively targeting the septal substrate to achieve moderate long-term VT control.

Original languageEnglish (US)
Pages (from-to)1169-1176
Number of pages8
JournalHeart Rhythm
Issue number8
StatePublished - Aug 1 2011


  • Cardiomyopathy
  • Catheter ablation
  • Electroanatomic mapping
  • Heart failure
  • Ventricular tachycardia

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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