One-Year Data From Global Atrial Fibrillation (AF) Registry Show Antithrombotic Agents Not Optimally Used to Prevent Stroke

-- GARFIELD Registry presentations at ESC CONGRESS 2013 provide outcomes data on real-world treatment patterns of at-risk AF populations --

AMSTERDAM, Sept. 3, 2013 /PRNewswire/ -- One-year outcomes data from the first cohort of the Global Anticoagulant Registry in the FIELD (GARFIELD), an innovative, independent academic research initiative, provide insights into the elevated stroke risk among subpopulations of patients with atrial fibrillation (AF).  The findings, from eight abstracts presented this week at the ESC Congress 2013, collectively show that anticoagulant therapy -- which is known to significantly lower stroke risk in AF patients -- is consistently under-utilised among those at-risk AF patients.

GARFIELD is led by an international steering committee under the auspices of the Thrombosis Research Institute (TRI), London. It is an international, observational, multicentre, prospective study designed to understand the global burden of AF, a common condition in which the two upper chambers of the heart (the atria) quiver rather than beat rhythmically and can lead to life-threatening complications, including stroke. Up to 2% of the population has AF.(1) Despite the availability of highly effective preventive treatments, AF-related stroke remains a major and increasing clinical and societal burden.

"These 1-year data from GARFIELD illustrate that evidence-based stroke prevention guidelines are not always followed in everyday clinical practice," said Professor The Lord Ajay Kakkar, Professor of Surgery at University College London and Director of the TRI, London UK . "Taken together, these new findings re-emphasize what has been observed in clinical trials regarding stroke risk in AF patients.  The research suggests there are opportunities to improve patient outcomes through more consistent application of best practice and adoption of the many innovative therapies to prevent stroke in high-risk AF patients."

The data presented at ESC Congress 2013 are from the first of five GARFIELD cohorts.  The first cohort includes a total of 10,614 patients with non-valvular AF and at least one investigator-determined additional risk factor for stroke, recruited from 540 randomly-selected sites in 19 countries. Of these patients, 5,089 were recruited retrospectively as a validation cohort and 5,525 were recruited prospectively and comprise the study populations in these abstracts.  ESC Guidelines for the management of atrial fibrillation recommend that all patients at high risk of stroke be prescribed anticoagulation therapy with vitamin K antagonists (VKAs), unless contraindicated. High stroke risk is defined as a score >/=2 on the CHA2DS2-VASc risk score. Previously reported baseline data showed that in Cohort 1, 82.6% of patients had CHA2DS2-VASc >/=2 but only 62% of these patients received anticoagulant therapy.

Data for the stroke-risk stratification research presented at ESC Congress 2013 were available in 5,523 patients enrolled prospectively between December 2009 and October 2011. 

The 1-year data -- which are preliminary and should be interpreted with caution -- were included in one oral presentation and seven poster abstracts.  The oral presentation was featured at the State of the Art: Acute coronary syndromes - current guidelines and future prospects, a session that spotlighted the four highest-rated abstracts in this topic. 

Highlights of the data, which were adjusted for relevant confounding factors, include:

Oral Presentation

• Significantly lower use of VKAs in AF patients with acute coronary syndrome (ACS) vs. those without ACS (48.9% vs. 51.7%, respectively) despite a comparable risk of all-cause death, stroke/systemic embolism (SE), major bleeding and recurrent ACS after 1 year
  • 10.1% (n=559) of patients had a history of ACS, 44.0% (n=246) of whom had a history of stenting

Poster Presentations

• Higher risk profile and more frequent use of antithrombotic therapy in AF patients who have had a previous stroke or transient ischaemic attack (TIA) 
  • AF patients with previous stroke/TIA had a 44% increased risk of death (HR* 1.44, p=0.037) and were more than twice as likely to suffer stroke/SE (HR 2.27, p=0.004) within the first year of diagnosis than patients who had not previously suffered stroke/TIA
  • More AF patients with previous stroke/TIA received VKAs (58.1% vs. 50.5% for no previous stroke/TIA), though these anticoagulants were markedly underutilised in both groups
• Lower risk of death in AF patients receiving rhythm control (the use of medication to restore the normal heart rhythm) vs. rate control (the use of medication to lower the heart rate closer to normal)
  • Among patients studied, 38.1% (n=2,107) were on rhythm control and 49.8% (n=2,754) were on rate control therapy
  • AF patients on rhythm control therapy had a 28% lower risk of death (HR 0.72, p=0.041) compared with patients on rate control therapy
  • Patients on rhythm control were younger and had a lower stroke risk score
  • The two groups differed in many aspects so there may be some residual confounding variables affecting the finding
• Higher overall risk profile for AF patients who have coronary artery disease (CAD)
  • 19.3% (n=1,066) of the study patients had CAD -- these patients were older, more likely to be male, and more likely to receive VKA in combination with antiplatelet (AP) therapy than non-CAD patients
  • AF patients with CAD had more than twice the risk for ACS than non-CAD patients (HR 2.49, p=0.016) but a comparable risk of death, stroke/SE and major bleeds
• Lower rate of VKA usage in patients with paroxysmal AF vs. permanent AF despite a comparable level of stroke and systemic embolism risk
  • 24.4% (n=1,348) of study patients had paroxysmal AF vs. 14.2% (n=785) with permanent AF
  • VKAs, alone or in combination with AP, were used in 39.1% of paroxysmal AF patients and 61.0% of permanent AF patients
  • Risk of death was 38% lower in patients with paroxysmal vs. permanent AF (HR 0.62, p=0.057)
  • Stroke/systemic embolism risk was similar in both patient groups (HR=1.18, p=0.72)
• Lower stroke risk and less frequent use of anticoagulants in newly diagnosed AF patients from Asia vs. Europe
  • 28.7% (n=1,587) of patients were enrolled in Asia and 58.6% (n=3,237) were enrolled in Europe
  • Patients in Asia were, on average, more likely to be male, younger, have a lower body mass index and have fewer comorbidities than those in Europe
  • Regardless of risk level, VKA usage was significantly higher in Europe (61.4%) vs. Asia (35.8%), highlighting substantial differences in the use of available stroke-prevention therapies  
• Less frequent use of VKAs among patients with new vs. permanent AF, though a similar rate of death and stroke between the two groups
  • 44.8% (n=2,477) of patients had new AF vs. 14.2% (n=785) with permanent AF 
  • Use of VKAs, alone or in combination with APs, was lower in patients with new AF (52.1%) vs. permanent AF (61.0%)
  • Stroke/systemic embolism risk was 47% increased in patients with permanent vs. new AF, though this difference was not statistically significant (HR 1.47, p=0.36)
  • New AF patients were slightly younger in age
• Underutilisation of anticoagulants among a sizeable proportion of AF patients undergoing direct current conversion (DCC+) -- a technique to get the heart into a normal sinus rhythm -- despite guidelines recommending their use for stroke prevention
  • Few patients -- 11.1% (n=614) patients -- in the registry underwent DCC within four months of diagnosis, even though they were newly diagnosed with AF
  • Patients undergoing DCC were more likely to receive VKA therapy than patients not undergoing the procedure.  However, 6.9% of DCC+ patients received no antithrombotic therapy and 12.5% received only AP
  • Outcomes of all-cause death, stroke/SE or major bleed at 1 year did not differ between groups