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Background: With the advent of cardiac resynchronization therapy, it was unclear what percentage of biventricular pacing would be required to obtain maximal symptomatic and mortality benefit from the therapy. The optimal percentage of biventricular pacing and the association between the amount of continuous pacing and survival is unknown., Objective: The purpose of this study was to assess the optimal percentage of biventricular pacing and any association with survival in a large cohort of networked patients., Methods: A large cohort of 36,935 patients followed up in a remote-monitoring network, the LATITUDE Patient Management system (Boston Scientific Corp., Natick, Massachusetts), was assessed to determine the association between the percentage of biventricular pacing and mortality., Results: The greatest magnitude of reduction in mortality was observed with a biventricular pacing achieved in excess of 98% of all ventricular beats. Atrial fibrillation and native atrial ventricular condition can limit a high degree of biventricular pacing. Incremental increases in mortality benefit are observed with an increasing percentage of biventricular pacing., Conclusion: Every effort should be made to reduce native atrioventricular conduction with cardiac resynchronization therapy systems in an attempt to achieve biventricular pacing as close to 100% as possible., (Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Clinical registries have been created to address questions that are difficult to answer with clinical trials. However, the applicability of registry findings to the general population has been questioned because of concerns over potential bias in the selection of participating hospitals. The purpose of this study was to determine if patients admitted to hospitals participating in a heart failure registry (ADHERE) are comparable with patients admitted to other hospitals, including those admitted to Framingham area hospitals., Methods: We used a 20% random sample of all Medicare patients discharged during 1984 to 2001 to determine rates of hospitalization, procedure use, and survival after a first admission for heart failure (none in the prior 3 years). Hospitals were classified as participating in the ADHERE registry (n = 189), located within or near Framingham, MA (n = 9), or other (n = 5541)., Results: A total of 725,702 first admissions were identified, including 80,338 to ADHERE hospitals and 1716 to Framingham area hospitals. Minimal differences in patient characteristics were noted between patients admitted to ADHERE and non-ADHERE hospitals, although patients admitted to Framingham area hospitals were more likely to be white (95%) than were patients admitted to ADHERE (84%) or other hospitals (87%, P < .0001). Mortality at 1 year was 35.8% for ADHERE, 36.2% for other hospitalized patients, and 32.9% for Framingham patients (P < .0001). Rehospitalization for heart failure at 90 days was 13.0% for following admission to ADHERE, 13.0% to other hospitals, and 16.4% to Framingham hospitals (P = .0004). After adjustment for patient characteristics, differences in outcome between ADHERE and non-ADHERE hospitals remained minimal., Conclusion: Patients admitted with heart failure to ADHERE registry hospitals had similar baseline characteristics and outcomes to other patients.