Response to letter regarding article, "Cardiac biomarkers are associated with an increased risk of stroke and death in patients with atrial fibrillation: a randomized evaluation of long-term anticoagulation therapy (RE-LY) substudy".

We thank Gonzales et al for their valuable comments on the article on biomarkers from The Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial.1 The RE-LY trial included 18 113 patients with atrial fibrillation, cardiac biomarkers were analyzed from plasma samples obtained at randomization in 6189 of the participants. The results showed that both N-terminal pro-B-type natriuretic peptide (NT-proBNP) and troponin I were strongly and independently related to thromboembolic outcomes regardless of clinical risk factors including heart failure. At randomization, all patients were classified as either having heart failure or not based on New York Heart Association class and on available information regarding previous measurements of left ventricular ejection fraction based on echocardiography, radionuclide, or angiogram assessments.2 NT-proBNP is a sensitive biomarker of left ventricular function, clinical heart failure, and a predictor of …