Decreased relative wall thickness (RWT) was associated with an increase of ventricular arrhythmia (VA) and VA/death in patients with mild heart failure (HF) and left bundle branch block, according to research published in the Journal of the American College of Cardiology.
Investigators sought to examine the relationship between RWT and the risk for VA in 1260 patients enrolled in the MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy) study.
These patients had ischemic cardiomyopathy (New York Heart Association function class I or II), left ventricular ejection fraction (LVEF) ≤30%, normal sinus rhythm, and QRS duration ≥130 ms, and were randomized to receive cardiac resynchronization therapy with defibrillator (CRT-D) or implantable cardioverter-defibrillator (ICD) therapy in a 3:2 ratio.
Three tertiles of patients were established: 1 low RWT (<0.24) and 2 upper tertiles with high RWT (≥0.24). CRT-D therapy was associated with a greater increase in RWT compared with ICD therapy (4.6% ± 6.8% vs 1.5% ± 2.7%; P<.001).
The first occurrence of VT/VF after 3 years of echocardiographic response was significantly lower in patients with increased RWT compared with those with lower changes in RWT at 12 months. For every 10% increase of RWT at 12 months with CRT-D, there were reductions in subsequent VA events (34%; P=.027) and VA/death rates (36%; P=.009), respectively.
In both ischemic and nonischemic subgroups, baseline RWT was a significant predictor of VT/VF (hazard ratio [HR]: 1.11; 95% confidence interval [CI]: 1.04-1.19; P=.001 and HR: 1.12; 95% CI: 1.06-1.18; P<.0001; respectively). At 12 months, the same finding was evident in RWT assessment; therefore, RWT increase was associated with risk reduction for VT/VF in both subgroups (P for interaction=.478).
“Defining baseline degree of eccentric hypertrophy using RWT measurement can be useful for prediction of VA in patients with impaired LVEF and mild HF,” researchers concluded. “Furthermore, among patients implanted with a CRT-D device, the magnitude of RWT increase attributed to CRT-D can predict VA risk as well.”
Prospective clinical studies are needed to confirm the RWT therapeutic implications in these patients with respect to pharmacological treatment, ICD programming, and cardiac resynchronization.
Biton Y, Goldenberg I, Kutyifa V, et al. Relative wall thickness and the risk for ventricular tachyarrhythmias in patients with left ventricular dysfunction. J Am Coll Cardiol. 2016;67(3):303-312. doi: 10.1016/j.jacc.2015.10.076.