Global Atrial Fibrillation Registry Data Show Poor Anticoagulation Control and High Risk Scores Increase Mortality and Strokes

News provided by

Thrombosis Research Institute (TRI)

22 Jun, 2015, 19:00 GMT

TORONTO, June 22, 2015 /PRNewswire/ --

-- One-year outcomes from the GARFIELD-AF Registry show poor VKA control and high risk scores increased mortality and strokes in newly diagnosed atrial fibrillation (AF) patients -- 

Real-life data from nearly 17,200 patients enrolled in the Global Anticoagulant Registry in the Field - Atrial Fibrillation (GARFIELD-AF) confirm that failing to achieve adequate management of anticoagulation with vitamin K antagonists (VKA) and high risk scores are associated with increased risk of mortality and stroke in patients with non-valvular AF. These findings were presented in two oral presentations at the 2015 Congress of the International Society on Thrombosis and Haemostasis (ISTH) today.

"Patients with newly diagnosed atrial fibrillation followed in the GARFIELD-AF Registry carry an important burden of disease in the first year after diagnosis," said Professor Ajay Kakkar, Professor of Surgery at University College London, and Director of the Thrombosis Research Institute. "The data recently presented from the GARFIELD-AF study emphasised the benefits of effective anticoagulation for appropriate patients with newly diagnosed atrial fibrillation."

The presentations at the ISTH congress were as follows:

Risk profiles and 1-year outcomes of patients with newly diagnosed atrial fibrillation: Results from GARFIELD-AF 

The incidence of stroke/systemic embolism, death and major bleeding one year after a new diagnosis of non-valvular AF were analysed by patients' baseline characteristics and antithrombotic therapy provided at diagnosis. The results showed that:  

  • Mortality is the highest burden in the first year after a diagnosis of AF
  • Higher risk scores (CHA2DS2-VASc and HAS-BLED) are associated with increased risk of death, stroke/SE and major bleeding events
  • Smoking, age ≥75 years, lack of anticoagulant treatment and kidney disease are also associated with increased risks of death, stroke/SE and major bleeding events
  • Cardiac failure at baseline is associated with increased risk of death, but hypertension at baseline reduces the risk of death

Quality of vitamin K antagonist control and 1-year outcomes: A global perspective from the GARFIELD-AF registry  

The study analysed time in therapeutic range (TTR) of international normalised ratio (using the target range of 2.0-3.0) in patients with newly diagnosed non-valvular AF in relation to demographics, care settings and 1-year outcomes. TTR is an indicator of the quality of VKA control and may also be used as an indicator of outcome. European Society of Cardiology guidelines recommend a TTR of ≥70%.[1] The results showed that:

  • Poor VKA control was associated with increased risk of mortality and stroke/systemic embolism (SE)
  • Increasing TTR from 60% to 70% may reduce the risk of stroke/SE
  • Fewer patients diagnosed at a hospital have good control versus patients diagnosed at an office or anticoagulation clinic/thrombosis centre
  • Heavy alcohol consumption is more frequent in patients with poor control
  • Overall, good VKA control is of major clinical importance

These new GARFIELD-AF analyses were based on data from Cohorts 1 and 2, which included 17,168 patients recruited between 2010 and 2013.

GARFIELD-AF is an independent academic research initiative, led by an international steering committee under the auspices of the Thrombosis Research Institute (TRI), London, UK. To date, GARFIELD-AF has recruited over 40,000 patients with newly diagnosed AF in 35 countries, making it one of the largest observational studies in this therapeutic area. With recruitment for Cohort 5 about to start, the Registry will eventually include up to 57,000 patients.

About the GARFIELD-AF Registry  

GARFIELD-AF is an observational, multicentre, international prospective study of patients with newly diagnosed AF. It will prospectively follow up to 57,000 patients from at least 1,000 centres in 35 countries in the Americas, Eastern and Western Europe, Asia, Africa and Australia. The start of the Registry coincided with the beginning of the non-vitamin K anticoagulants (NOACs) era of treatment for AF.

Contemporary understanding of AF is based on data gathered in controlled clinical trials. Whilst essential for evaluating the efficacy and safety of new treatments, these trials are not representative of everyday clinical practice and, hence, uncertainty persists about the real-life burden and management of this disease. GARFIELD-AF seeks to provide insights into the impact of anticoagulant therapy on thromboembolic and bleeding complications seen in this patient population. It will provide a better understanding of the potential opportunities for improving care and clinical outcomes amongst a representative and diverse group of patients and across distinctive populations. This should help physicians and healthcare systems to appropriately adopt innovation to ensure the best outcomes for patients and populations.

The registry started in December 2009. Four key design features of the GARFIELD-AF protocol ensure a comprehensive and representative description of AF, these are:

  • Five sequential cohorts of prospective, newly-diagnosed patients, facilitating comparisons of discrete time periods and describing the evolution of treatments and outcomes.
  • Investigator sites that are selected randomly within carefully assigned national AF care setting distributions, ensuring that the enrolled patient population is representative.
  • Enrolment of consecutive eligible patients regardless of therapy to eliminate potential selection bias.
  • Follow-up data captured for a minimum of 2 and up to 8 years after diagnosis, to create a comprehensive database of treatment decisions and outcomes in everyday clinical practice.

Included patients must have been diagnosed with non-valvular AF within the previous 6 weeks and have at least one additional risk factor for stroke; as such they are potential candidates for anticoagulant therapy to prevent blood clots leading to stroke. It is left to the investigator to identify a patient's stroke risk factor(s), which need not be restricted to those included in established risk scores. Patients are included whether or not they receive anticoagulant therapy, so current and future treatment strategies and failures can be properly understood in relation to patients' individual risk profiles.

The GARFIELD-AF Registry is funded by an unrestricted research grant from Bayer Pharma AG.


The burden of AF  

Up to 2% of the global population has AF.[2] Around 6 million people in Europe[3], 3-5 million people in the United States[4],[5] and up to 8 million people in China have AF.[6],[7] It is estimated that its prevalence will at least double by 2050 as the global population ages. AF confers a five-fold increase in the risk of stroke, and one in five of all strokes is attributed to this arrhythmia. Ischaemic strokes associated with AF are often fatal, and those patients who survive are left more frequently and more severely disabled and more likely to suffer a recurrence than patients with other causes of stroke. In consequence, the risk of death from AF-related stroke is doubled and the cost of care is increased by 50%.[8]

AF occurs when parts of the atria emit uncoordinated electrical signals. This causes the chambers to pump too quickly and irregularly, not allowing blood to be pumped out completely.[9] As a result, blood may pool, clot and lead to thrombosis, which is the number one cardiovascular killer in the world.[10] If a blood clot leaves the left atrium, it could potentially lodge in an artery in other parts of the body, including the brain. A blood clot in an artery in the brain leads to a stroke. Ninety-two per cent of fatal strokes are caused by thrombosis.[10] People with AF are also at high risk for heart failure, chronic fatigue and other heart rhythm problems.[11] Stroke is a major cause of death and long-term disability worldwide - each year 6.7 million people die[12] and 5 million are left permanently disabled.[13]

About the TRI  

The TRI is a charitable foundation and multi-disciplinary research institute dedicated to the study of thrombosis and related disorders. TRI's mission is to provide excellence in thrombosis research and education, to develop new strategies to prevent and treat thrombosis and thereby improve quality of care, advance clinical outcomes and reduce healthcare costs. The TRI is a member of University College London Partners Academic Health Science System.

For more information, visit http://www.tri-london.ac.uk/garfield.

  1. Camm AJ, Lip GY, De Caterina R, et al. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association. Eur Heart J. 2012;33(21):2719-47.
  2. Davis RC, Hobbs FD, Kenkre JE, et al. Prevalence of atrial fibrillation in the general population and in high-risk groups: the ECHOES study. Europace 2012; 14(11):1553-9. 6/16/15. Available at: http://europace.oxfordjournals.org/content/14/11/1553.long
  3. The Lancet Neurology. Stroke prevention: getting to the heart of the matter. Lancet Neurol 2010; 9(2):129. 6/16/15. Available at: http://www.atrialfibrillation.org.uk/files/file/Articles_Medical/Lancet%20Neurology-%20getting%20to%20the%20heart%20of%20the%20matter.pdf
  4. Naccarelli GV, Varker H, Lin J, et al. Increasing prevalence of atrial fibrillation and flutter in the United States. Am J Cardiol 2009; 104(11):1534-9.
  5. Colilla S, Crow A, Petkun W, et al. Estimates of current and future incidence and prevalence of atrial fibrillation in the U.S. adult population. Am J Cardiol 2013; 112(8):1142-7. 6/16/15. Available at: http://www.ajconline.org/article/S0002-9149(13)01288-5/fulltext
  6. Zhou Z, Hu D. An epidemiological study on the prevalence of atrial fibrillation in the Chinese population of mainland China. J Epidemiol 2008; 18(5):209-16. 6/16/15. Available at: https://www.jstage.jst.go.jp/article/jea/18/5/18_JE2008021/_pdf
  7. Hu D, Sun Y. Epidemiology, risk factors for stroke, and management of atrial fibrillation in China. JACC 2008; 52(10):865-8. 6/16/15. Available at: http://www.sciencedirect.com/science/article/pii/S0735109708021141
  8. European Heart Rhythm Association; European Association for Cardio-Thoracic Surgery, Camm AJ, Kirchhof P, Lip GY, et al. Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). 8/22/14. Eur Heart J 2010; 31(19):2369-429. 6/16/15. Available at: http://eurheartj.oxfordjournals.org/content/early/2010/09/25/eurheartj.ehq278.full
  9. National Heart, Lung, and Blood Institute. What is Atrial Fibrillation? 6/16/15. Available at: http://www.nhlbi.nih.gov/health/dci/Diseases/af/af_what.html
  10. International Society on Thrombosis and Haemostasis. About World Thrombosis Day. Available at: http://www.worldthrombosisday.org/about/
  11. American Heart Association. Why Atrial Fibrillation (AF or AFib) Matters. 8/22/14. Available at: http://www.heart.org/HEARTORG/Conditions/Arrhythmia/AboutArrhythmia/Why-Atrial-Fibrillation-AF-or-AFib-Matters_UCM_423776_Article.jsp
  12. World Health Organization. The top 10 causes of death. Fact sheet N°310. Updated May 2014. 6/16/15. Available at: http://www.who.int/mediacentre/factsheets/fs310/en/
  13. World Heart Federation. The global burden of stroke. 6/16/15. Available at: http://www.world-heart-federation.org/cardiovascular-health/stroke/