BACKGROUND: Heart failure (HF) is a common medical problem with significant morbidity and mortality. Recently, device-based therapy, cardiac resynchronization therapy (CRT), implantable cardioverter-defibrillators (ICDs), and combined CRT and ICD have become established therapies in patients with HF receiving standard medical therapy. Contemporary implantable devices are able to continuously monitor, store, and display long-term diagnostic information. Daily diagnostic information includes intrathoracic impedance, patient activity, hours spent in atrial tachycardia/fibrillation, ventricular rate during atrial tachycardia/fibrillation, ventricular tachyarrhythmia episodes, ICD shocks, day and night heart rate, and heart rate variability. METHODS: PARTNERS HF is a prospective, nonrandomized, multicenter observational study. Patient data are collected at baseline and at 3, 6, 9, and 12 months. Our objectives are to assess the relationship between the (1) diagnostic data and HF-related events, (2) diagnostic data and HF-related health care utilizations, and (3) OptiVol (Medtronic, Inc, Minneapolis, MN) fluid monitoring diagnostic data and clinically relevant pulmonary congestion events in a subset of patients. The study has enrolled 1,024 patients with a commercially available combined CRT and ICD system at 100 sites in the United States. Participants will be followed for 1 year. RESULTS: Enrollment was completed in January 2007. Key baseline characteristics include the following: mean age of 68.4+/-10.8 years, 32% female, 13% people of color, 64% with ischemic HF, and >80% of patients reported to be on recommended HF medications at enrollment. CONCLUSIONS: The results of PARTNERS HF could help identify device diagnostic information that may provide an early recognition of impending HF-related events.