AMSTERDAM - Investigators are reporting widespread underuse of anticoagulant therapy in patients with atrial fibrillation (AF) who are at high risk of stroke, despite the fact that such therapy is known to decrease stroke risk in this population.

The findings were released at the European Society of Cardiology (ESC) Congress 2013 and represent one-year outcomes from the ongoing Global Anticoagulant Registry in the Field (GARFIELD), which is the largest prospective database tracking AF patients at increased stroke risk.

"The one-year data from GARFIELD illustrate that evidence-based stroke prevention guidelines are not always followed in routine clinical practice," Professor The Lord Ajay Kakkar, MBBS, Professor of Surgery at University College London, UK, and Director of the Thrombosis Research Institute, commented.

Current ESC guidelines for AF management advocate the use of anticoagulation therapy with vitamin K antagonists in all patients at high risk of stroke unless contraindicated because of complications such as a risk of excess bleeding.

The new data are from the first of five GARFIELD cohorts and include 10,614 adult patients who were diagnosed with non-valvular AF within the past six weeks and had at least one additional risk factor for stroke, which renders them eligible for anticoagulant therapy for stroke prevention.

Eventually, the registry will enroll about 50,000 individuals from 50 countries worldwide. Notably, investigator sites are representative of the distribution of AF care settings in each country. As such, patients are referred by general practitioners/family physicians, office-based cardiologists, internists, clinics and hospitals including thrombosis clinics, and emergency departments.

Among the findings reported thus far:

  • Significantly lower use of vitamin K antagonists in AF patients with acute coronary syndromes (ACS) versus those without ACS (48.9% versus 51.7%, respectively) despite a similar risk of all-cause death, stroke/systemic embolism, major bleeding, and recurrent ACS at one year.

  • Significantly lower rate of vitamin K antagonist use in patients with paroxysmal AF versus permanent AF despite a similar risk of stroke and systemic embolism. For example, 31.2% of patients with paroxysmal AF received only vitamin K antagonists versus 49.2% of patients with permanent AF. Also, 7.9% and 11.8% of the two groups, respectively, received a vitamin K antagonist and anti-platelet therapy.

  • Less frequent use of vitamin K antagonists in patients with new versus permanent atrial fibrillation despite a similar rate of death or stroke/SE at one year. Overall, 52.1% of patients with new AF used vitamin K antagonists alone or combined with anti-platelet therapy versus 61% of patients with permanent AF.

Lord Kakkar pointed out that AF is the most common sustained cardiac arrhythmia. Roughly 16 million strokes occur per year worldwide, and 20% are attributable to AF. Strokes associated with AF are more severe and confer an increased risk of morbidity, mortality, and poor functional outcome.

"What's striking is the consistency with which we in clinical practice fail to provide interventions that would in themselves help alleviate and reduce the risk for the development of stroke in the background of atrial fibrillation once identified," he said.

The investigator added: "In terms of cardio-embolic stroke, over half of it is attributed to non-valvular atrial fibrillation. And it is striking once again, that with all this knowledge about the epidemiology about the risk for the development of stroke in the background of atrial fibrillation, we continue to fail to provide interventions, particularly anticoagulation, that could have a profound impact not only on improving outcomes for the individual patient but also a profound impact on population health and, of course, the appropriate utilization of valuable and scarce resources in our health care systems."

Jill Stein is a Paris-based freelance medical writer.