OBJECTIVES: The aim of this study was to determine whether left ventricular (LV) 
midwall fibrosis, detected by midwall hyperenhancement (MWHE) on late gadolinium 
enhancement cardiovascular magnetic resonance (CMR) imaging, predicts mortality 
and morbidity in patients with dilated cardiomyopathy (DCM) undergoing cardiac 
resynchronization therapy (CRT).
BACKGROUND: Midwall fibrosis predicts mortality and morbidity in patients with 
DCM.
METHODS: Patients with DCM with (+) or without (-) MWHE (n = 20 and n = 77, 
respectively) as well as 161 patients with ischemic cardiomyopathy (ICM) 
undergoing CRT (n = 258) were followed up for a maximum of 8.7 years.
RESULTS: Among patients with DCM, +MWHE predicted cardiovascular mortality 
(hazard ratio [HR]: 18.6; 95% confidence intervals [CI]: 3.51 to 98.5; p = 
0.0008), total mortality or hospitalization for major adverse cardiovascular 
events (HR: 7.57; 95% CI: 2.71 to 21.2; p < 0.0001), and cardiovascular 
mortality or heart failure hospitalizations (HR: 9.56; 95% CI: 2.72 to 33.6; p = 
0.0004), independent of New York Heart Association class, QRS duration, atrial 
fibrillation, LV volumes, LV ejection fraction, and a CMR-derived measure of 
dyssynchrony. Among patients with DCM and ICM, the risk of cardiovascular 
mortality for DCM +MWHE (adjusted HR: 18.5; 95% CI: 3.93 to 87.3; p = 0.0002) 
was similar to that for ICM (adjusted HR: 21.0; 95% CI: 5.06 to 87.2; p < 
0.0001). Both DCM +MWHE and ICM were predictors of pump failure death as well as 
sudden cardiac death. LV reverse remodeling was observed in DCM -MWHE and in ICM 
but not in DCM +MWHE.
CONCLUSIONS: Midwall fibrosis is an independent predictor of mortality and 
morbidity in patients with DCM undergoing CRT. The outcome of DCM with midwall 
fibrosis is similar to that of ICM. This relationship is mediated by both pump 
failure and sudden cardiac death.