Studies estimate atrial fibrillation affected between 2 and 3 million Americans in 2005. Those same studies estimate the prevalence of atrial fibrillation will likely increase to between 3.8 million and 4.8 million by 2025. Industry estimates expect the atrial fibrillation drug market in developed countries to increase more than eight-fold, from $843 million in 2009 to $6.8 billion in 2019. The Company believes there is an unmet medical need for new atrial fibrillation treatments that have fewer side effects than currently available therapies and are more effective, particularly in patients with HFREF, where most of the approved atrial fibrillation drugs are contra-indicated or have warnings in their prescribing information.Gencaro Atrial Fibrillation Clinical Trial The Company plans to conduct a multi-center, randomized, double-blind clinical trial of Gencaro in symptomatic persistent atrial fibrillation patients with HFREF. The Company believes the planned study will provide important clinical data on the safety and efficacy of Gencaro in this patient population and additional information on the potential pharmacogenetic selectivity of Gencaro. The Company is planning for the atrial fibrillation trial to compare Gencaro to the beta-blocker metoprolol CR/XL in patients with the genotype (homozygous arginine position of the beta 1389 adrenergic receptor) in which Gencaro appears to demonstrate therapeutic enhancement. Metoprolol CR/XL does not appear to have enhancement of efficacy in patients with this genotype. The Company believes the planned trial would take approximately 2.5 years from enrollment of the first patient to completion, including data analysis. Subject to obtaining additional financing, the Company anticipates initiating patient enrollment in the trial in the first half of 2012. About ARCA biopharma ARCA biopharma is dedicated to developing genetically-targeted therapies for cardiovascular diseases. The Company's lead product candidate, Gencaro TM (bucindolol hydrochloride), is an investigational, pharmacologically-unique beta-blocker and mild vasodilator being developed for the prevention of atrial fibrillation in patients with heart failure. ARCA has identified common genetic variations in the cardiovascular system that it believes interact with Gencaro’s pharmacology and may predict individual patient response to Gencaro, giving it the potential to be the first genetically-targeted treatment for the prevention of atrial fibrillation. ARCA is collaborating with Laboratory Corporation of America to develop the companion genetic test for Gencaro. For more information, please visit www.arcabiopharma.com. Safe Harbor Statement This press release and the anticipated presentations may contain "forward-looking statements" for purposes of the safe harbor provided by the Private Securities Litigation Reform Act of 1995. These statements include, but are not limited to, statements regarding the adequacy of the Company’s capital to support the Company’s operations, the ability of genetic variations to predict individual patient response to Gencaro; the potential for Gencaro to be the first genetically-targeted heart failure and/or atrial fibrillation prevention treatment; the projected increase in prevalence of atrial fibrillation; the projected increase in the size of the atrial fibrillation drug market in developed countries; and, the potential for the planned atrial fibrillation clinical trial provide important data on the safety and efficacy of Gencaro in the trial population. Such statements are based on management's current expectations and involve risks and uncertainties. Actual results and performance could differ materially from those projected in the forward-looking statements as a result of many factors, including, without limitation, the risks and uncertainties associated with: the Company's financial resources and whether they will be sufficient to meet the Company's business objectives and operational requirements; the protection and market exclusivity provided by the Company’s intellectual property; risks related to the drug discovery and the regulatory approval process; and, the impact of competitive products and technological changes. These and other factors are identified and described in more detail in ARCA’s filings with the SEC, including without limitation the Company’s annual report on Form 10-K for the year ended December 31, 2010 and subsequent filings. The Company disclaims any intent or obligation to update these forward-looking statements.