Scar progression in patients with nonischemic cardiomyopathy and ventricular arrhythmias.

Background: Disease progression in patients with nonischemic cardiomyopathy (NICM) is poorly understood.
Objective: To assess left ventricular (LV) scar progression and dilatation by using endocardial electroanatomic mapping.
Methods: We studied 13 patients with NICM and recurrent ventricular tachycardia. Two detailed sinus rhythm endocardial voltage maps (265 ± 122 points/map) were obtained after a mean of 32 months (range 9-77 months). The scar area, defined by low bipolar (BI; <1.5 mV) and unipolar (UNI; <8.3 mV) endocardial voltage, and the LV volume were measured and compared. A scar difference of >6% of the LV surface and an increase in LV volume of ≥20 mL were considered beyond measurement error.
Results: Six (46%) patients had an increase in scar area beyond boundaries of prior ablation. Five patients had an increase in UNI and 1 patient had an increase in both BI and UNI areas. The increase in BI area represented 16% and the increase in UNI area represented 6.5%-46.2% of the LV surface. A significant decrease in LV ejection fraction was found only in patients with scar progression (from 39% ± 8% to 32% ± 8%; P = .003). LV dilation (LV volume increase ranging between 9% and 23%) was noted in 3 patients, all of whom had scar progression.
Conclusions: Progressive scarring with an increase in the area of UNI and less commonly BI electrogram abnormality is seen in 46% of the patients with NICM and ventricular tachycardia and is associated with LV dilatation and decrease in LV ejection fraction. The prominent UNI abnormality suggests predominantly midmyocardial or epicardial scarring.
(Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)