Magnetic resonance assessment of the substrate for inducible ventricular tachycardia in nonischemic cardiomyopathy.
BACKGROUND
Patients with left ventricular dysfunction have an elevated risk of sudden cardiac death. However, the substrate for ventricular arrhythmia in patients with nonischemic cardiomyopathy remains poorly understood. We hypothesized that the distribution of scar identified by MRI is predictive of inducible ventricular tachycardia.


RESULTS
Short-axis cine steady-state free-precession and postcontrast inversion-recovery gradient-echo MRI sequences were obtained before electrophysiological study in 26 patients with nonischemic cardiomyopathy. Left ventricular ejection fraction was measured from end-diastolic and end-systolic cine images. The transmural extent of scar as a percentage of wall thickness (percent scar transmurality) in each of 12 radial sectors per slice was calculated in all myocardial slices. The percentages of sectors with 1% to 25%, 26% to 50%, 51% to 75%, and 76% to 100% scar transmurality were determined for each patient. Predominance of scar distribution involving 26% to 75% of wall thickness was significantly predictive of inducible ventricular tachycardia and remained independently predictive in the multivariable model after adjustment for left ventricular ejection fraction (odds ratio, 9.125; P=0.020).


CONCLUSIONS
MR assessment of scar distribution can identify the substrate for inducible ventricular tachycardia and may identify high-risk patients with nonischemic cardiomyopathy currently missed by ejection fraction criteria.
Nazarian
Saman
S
Department of Medicine/Cardiology, Johns Hopkins Hospital, Baltimore, MD 21287, USA. snazari1@jhmi.edu
Bluemke
David A
DA
Lardo
Albert C
AC
Zviman
Menekhem M
MM
Watkins
Stanley P
SP
Dickfeld
Timm L
TL
Meininger
Glenn R
GR
Roguin
Ariel
A
Calkins
Hugh
H
Tomaselli
Gordon F
GF
Weiss
Robert G
RG
Berger
Ronald D
RD
Lima
João A C
JA
Halperin
Henry R
HR
D009202:Cardiomyopathies / Q000473:pathology*; D016757:Death, Sudden, Cardiac; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009206:Myocardium / Q000473:pathology; D018487:Ventricular Dysfunction, Left / Q000473:pathology*