ARCA biopharma, Inc. (Nasdaq: ABIO), a biopharmaceutical company developing genetically-targeted therapies for atrial fibrillation and other cardiovascular diseases, today announced results of analyses of atrial fibrillation and pharmacogenetic data from the BEST trial, a previously conducted Phase 3 heart failure trial involving Gencaro in 2,708 advanced heart failure patients. Pursuant to their analysis, researchers concluded that Gencaro substantially decreased the risk of new onset atrial fibrillation in a large moderate-to-severe heart failure population, with a risk reduction of 41%. Furthermore, the researchers concluded that patients with a specific genotype (homozygous arginine at beta-1 389) had a 74% risk reduction for new onset atrial fibrillation. Based on a DNA sub-study in the BEST trial, ARCA believes approximately 50% of U.S. population has this specific genotype. The data were selected for oral presentation at the American Heart Association’s Scientific Sessions 2011, being held November 12-16, 2011 in Orlando, Florida. Dr. Ryan Aleong, Assistant Professor of Medicine, Cardiology, Director of Implanted Cardiac Device Clinic, University of Colorado Hospital, and Interim Director of Arrhythmia Services at Denver Health Medical Center, presented the abstract “Prevention of Atrial Fibrillation by Bucindolol is Completely Dependent on the Beta-1 389 Arg/Gly Adrenergic Receptor Polymorphism.” Data presented in the abstract included:Beta blockers have modest efficacy for the prevention of atrial fibrillation in chronic heart failure/reduced ejection fraction (HFREF) populations, with risk reductions on the order of 20-40%. The researchers assessed the ability of the beta-blocker/sympatholytic agent Gencaro to prevent atrial fibrillation in the BEST trial, identifying new onset atrial fibrillation from adverse event/serious adverse event (AE/SAE) case report forms as well as routinely measured electrocardiograms (ECGs) in patients not in atrial fibrillation on study entry, and constructing Kaplan Meier curves using Cox regression. In the entire 2,708 patient cohort there were 115/1190 (9.7%) new onset atrial fibrillation episodes in baseline sinus rhythm patients in the placebo group, and 75/1202 (6.2%) in the Gencaro group. The time to event hazard ratio (95% CIs) was 0.59 (0.44, 0.79), p = 0.0004. In the 1,040 patient DNA substudy based on 80 total events the hazard ratio was 0.57 (0.36, 0.90), p = 0.014) and the therapeutic effect was completely dependent on the beta-1 389 Arginine/Glycine polymorphism.