Response to Letter Regarding Article, “Impact of Proteinuria and Glomerular Filtration Rate on Risk of Thromboembolism in Atrial Fibrillation: The Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) Study”
We agree with Barrios et al that we need to improve our ability to identify which patients with atrial fibrillation are at higher risk for ischemic stroke, especially given the limited predictive value of the most widely used published risk stratification schemes in atrial fibrillation.1 Our study supports that 2 measures of kidney function, estimated glomerular filtration rate and urinary protein excretion, are independent predictors of ischemic stroke in atrial fibrillation even after accounting for other known clinical stroke risk factors.2 Current guidelines do not incorporate reduced kidney function in assessing an individual’s predicted risk of stroke in atrial fibrillation, but we believe it should be considered on the basis of our findings.
Although oral vitamin K antagonist therapy may be underused in patients with renal dysfunction, patients with significant chronic kidney disease were largely excluded from previous randomized trials of antithrombotic therapies. Further investigation is needed to delineate the net clinical benefit (ischemic strokes prevented versus major bleeds caused) of different preventative strategies in patients with atrial fibrillation at varying levels of kidney function in order to improve the antithrombotic therapy decision-making process in this understudied population.
Sources of Funding
This work is supported by Public Health Services grant AG15478 from the National Institute on Aging and the Edith and Eliot B. Shoolman Fund of Massachusetts General Hospital. Dr Go is supported by National Institute of Diabetes, Digestive, and Kidney Diseases grants U01DK060902 and U01DK082223; National Heart, Lung, and Blood Institute grant U19HL091179; the American Heart Association; and Johnson & Johnson.
Dr Singer has been a consultant for Boehringer Ingelheim, Bayer Healthcare, AstraZeneca, Sanofi Aventis, Daiichi Sankyo, and Johnson & Johnson, and he received speaking honoraria from Pfizer and Bristol Meyers Squibb. The remaining authors report no conflicts.
Go AS, Fang MC, Udaltsova N, Chang Y, Pomernacki NK, Borowsky L, Singer DE, ATRIA study investigators. Impact of proteinuria and glomerular filtration rate on risk of thromboembolism in atrial fibrillation: the anticoagulation and risk factors in atrial fibrillation (ATRIA) study. Circulation. 2009; 119: 1363–1369.