Under the new health law, a nonprofit entity called the Patient Centered Outcomes Research Institute will be established to carry out a comparative effectiveness research agenda, starting in 2012. The law bars the government from using findings as the sole basis for decisions about what Medicare, the federal health program for the elderly and disabled, will cover.

A-fib treatments are among the top priorities for comparative effectiveness research not only because the medical problem is so common and has so many different treatments, but also because the number of those afflicted is expected to grow, fueled by an aging population, an increased prevalence of heart disease and improved diagnosis.

And it’s costly: Medicare spends more than $15.7 billion annually to treat new A-fib patients, who are hospitalized more often than those who don’t have the condition, according to a 2008 study in the Journal of Medical Economics. Other research from 2006 estimated that A-fib results in 350,000 hospitalizations, 276,000 emergency room visits and 5 million doctor visits a year.

So far, studies have generally considered how well the treatments do at controlling A-fib over the course of about a year. But comparative effectiveness research would look at: Which treatments do better in the long run to control the condition? Which are better at preventing strokes or death? Which is most cost-effective? Should all patients try drug therapy first, as is common now, or should some go straight to catheter ablation or surgery?

Getting answers will be difficult, requiring multiple clinical trials over many years, says Sean Tunis, director of the Baltimore-based Center for Medical Technology Policy, a nonprofit that helps design comparative effectiveness studies.

A recently launched six-year, multinational study comparing drug treatment of A-fib to catheter ablation is expected to answer some of those questions, but final results won’t be in until 2015.