Ventricular resynchronization therapy (VRT) (left ventricular or bi-ventricular stimulation) has been recently explored as an adjunct therapy to drugs to treat symptoms of heart failure (HF) in patients with conduction delay. Although long term improvement in functional capacity has been reported with VRT, the dependence of benefit on etiology of heart failure, if any, is unclear. Our goal was to test the effect of ischemic (ICM) or non-ischemic (NICM) etiologies in HF patients on long term benefit achieved with VRT. Methods: Twenty-five patients (Age: 60 f 4 years, QRS: 171 z!= 25 ms, NYHA class 3.1 f 0.2, EF: 21 f 6%,) enrolled in the PATH-CHF study were included for analysis. 18 patients had heart failure from NICM and 7 patients due to ICM. The two groups were well matched for age, NYHA class and EF. The patients were stimulated for a period of 6 months with a one-month non-paced period from 4-8 weeks. Six-minute walk distance (6’WD) and quality of life score (QOL) were evaluated before implant and at the end of 6 months of follow-up. Two-tailed paired t-test analyses were done to compare the changes in 6’WD and QOL in both groups. Results: 6’WD and QOL data was missing from one patient in the NICM and ICM group respectively. I-IF patients with both NICM and ICM etiologies significantly benefit with VRT. The degree of benefit between the two groups is not different for 6’WD (P = 0.28) or QGL (P = 0.50).