Enhanced external counter pulsation (EECP) therapy has previously been shown to be beneficial for patients with chronic stable angina. However, data in patients with heart failure are scarce. The aim of the present trial was to evaluate the role of EECP in patients with stable heart failure with NYHA Class II or III symptoms, ischemic or non-ischemic etiology, left ventricular (LV) ejection fraction <35%, optimal pharmacologic therapy, ability to exercise >3 min, limited by shortness of breath or fatigue (not by angina). Patients were randomized to EECP with optimal pharmacologic therapy (n=93) or optimal pharmacologic therapy alone (n=94). EECP therapy consists of a series of inflatable cuffs that are rapidly inflated at the onset of diastole and rapidly deflated at the onset of systole in order to replicate the hemodynamic properties of intra-aortic balloon counter pulsation. EECP was administered for 35 sessions of 1-hour each and continued for 7 weeks. Patients underwent exercise stress test at baseline and 3 months. Optimal pharmacologic therapy included angiotensinconverting enzyme (ACE) inhibitors (76%) or angiotensin receptor blockers (ARB)(19%) and beta-blockers (85%). Baseline characteristics were well balanced between treatment groups. Ischemic etiology was present in 69% of patients and 65% were in NYHA class II. Baseline ejection fraction was 26%. Increase in exercise duration by at least 60 s at 6 months occurred more frequently in the EECP group compared with controls (35.4% v. 25.3%, p=0.016). There was no difference in the co-primary endpoint of increase in peak VO2 of at least 1.25 ml/min/ kg between groups (22.8% for EECP v. 24.1% for control, p=NS). Change in exercise duration was longer in the EECP group compared with control as early as one week (26.4 s increase v. 10.0 s decrease, p=0.01) and maintained through 6 months (24.7 s increase v. 9.9 s decrease, p=0.01). Improvement in NYHA class was more common in the EECP group compared with controls at 1 week (33.3% v. 11.4%, p<0.001) and maintained through 6 months (31.3% v. 14.3%, p<0.001). Change from baseline in Minnesota Living with Heart-Failure score was greater in the EECP group at 1 week (-8.9 v. -3.4, p=0.01) and 3 months (-7.1 v. -2.9, p=0.01) but did not differ at 6 months (-3.7 v. -2.9, p=NS). Serious adverse events were reported in 30.3% of the EECP group and 29.5% of the control group (p=NS). In conclusion, among patients with systolic dysfunction, stable heart failure symptoms and treated with optimal pharmacologic therapy, use of EECP was associated with improvement in exercise duration, NYHA class and quality of life but no difference in change in peak VO₂ compared with optimal pharmacologic therapy alone.