EU says Novartis MS drug needs heart monitoring LONDON/ZURICH (Reuters) - The European Medicines Agency advised doctors to continuously monitor patients for six hours after giving them a first dose of Novartis AG's multiple sclerosis drug Gilenya, casting a shadow over the potential blockbuster product. Friday's move came as the organization started a review into the safety of the medicine, following reports of heart problems in patients and the death of one person in the United States within 24 hours of starting treatment. The Swiss drugmaker said last month it was investigating whether Gilenya, seen by analysts as a potential multibillion-dollar seller, caused the death of the 59-year-old U.S. patient. Gilenya can temporarily slow the heart rate. Although this usually returns to normal after a few hours, the European watchdog recommended intense cardiovascular monitoring after the first dose. This should include electrocardiogram (ECG) monitoring before treatment and then continuously for the first six hours afterwards, as well as measurement of blood pressure and heart rate every hour. Mark Schoenebaum, an analyst at ISI Group, said the call for active ECG monitoring was very different from the U.S. Food and Drug Administration (FDA) recommendation of observation and could encourage European doctors to use Biogen Idec's experimental BG-12. "We believe active ECG monitoring for six hours could be a material impediment to starting patients on Gilenya and could enhance BG-12's attractiveness to EU physicians once approved," he said. The FDA said on December 20 it was also looking into the U.S. case. Regulators on both sides of the Atlantic said the exact cause of the patient's death was still unexplained. Novartis was not immediately available for comment. "It's a bit early to draw too many conclusions on the basis of just one case, but if this keeps happening and serious cardiovascular problems turn out to be an issue, then this will definitely spook doctors," Vontobel analyst Andrew Weiss said. European authorities approved Gilenya last March for people with highly active relapsing-remitting multiple sclerosis (RRMS), the commonest form of the debilitating disease. More than 30,000 people have received the drug worldwide. Novartis is banking on the success of its newest drugs, such as Gilenya, to help it protect its top and bottom lines as established medicines lose patent protection and face competition from cheaper copies. Analysts, on average, forecast annual sales of $1.8 billion by 2016, according to Thomson Reuters Pharma. Gilenya is likely to face increased competition as other drugmakers such as Biogen and Sanofi push ahead with their latest MS medicines. Some experts have tipped Biogen's BG-12 to become the world's leading treatment for multiple sclerosis, while Sanofi's Genzyme unit plans to submit Lemtrada for approval in the United States and Europe in the first quarter of 2012. BG-12's key competitive advantage may lie in its safety profile, which looks relatively clean based on two-year data, analysts have said. Multiple sclerosis affects 2.5 million people worldwide and is a chronic, often disabling disease that attacks the central nervous system and can lead to numbness, paralysis and loss of vision.