Citi maintained its buy recommendation on drugmaker AstraZeneca and said that regulatory approval for its heart drug in the US will provide "some comfort on the longer-term outlook for the business, especially beyond 2014," given the disappointment over the future of its diabetes drug.On Wednesday, blood-thinner brilinta was finally approved by the Food and Drug Administration in the US for use in reducing cardiovascular deaths and myocardial infarction in patients with acute coronary syndromes (ACS).Citi's analyst Mark Dainty, who had predicted a 60%-70% chance of FDA approval for brilinta, said the boxed warning about high dose aspirin interaction is "largely as expected" and the warning about bleeding is "not entirely surprising."Dainty pointed out that the Brilinta label is comparable with rival drug Plavix, the second biggest selling drug in the world, and much broader than another drug Effient, which is indicated only for those ACS patients who will be managed by stents."Brilinta can compete more effectively with Plavix than Effient because of this broader label. It can be used before the type of treatment is decided where as Effient must be used after," Dainty added.Bristol-Myers Squibb and Sanofi Aventis' blockbuster blood thinner Plavix is set to lose patent protection in 2012. AstraZeneca was among the top gainers on the FTSE 100 index. Shares of the company jumped 2.1% to 3,095p in London trading. BC