Soluble Fibrin Monomer Complex and Prediction of Cardiovascular Events in Atrial Fibrillation: The Observational Murcia Atrial Fibrillation Project.

BACKGROUND: Soluble fibrin monomer complex (SFMC) is a biomarker of fibrin formation abnormally elevated in clinical situations of hypercoagulability. OBJECTIVE: We investigated the association and predictive performance of SFMC for stroke, adverse cardiovascular events, cardiovascular mortality and all-cause mortality in a cohort of patients with atrial fibrillation (AF) receiving vitamin K antagonist (VKA) anticoagulant therapy. DESIGN: During the second semester of 2007, we included 1226 AF outpatients stable on VKAs (INR 2.0-3.0) over a period of 6 months. SFMC levels were assessed at baseline. During 6.5 (IQR 4.4-8.0) years of follow-up, we recorded all ischemic strokes, adverse cardiovascular events (composite of stroke, acute heart failure, acute coronary syndrome and cardiovascular death), cardiovascular deaths and all-cause deaths. PARTICIPANTS: All patients were recruited consecutively. We excluded patients with rheumatic mitral valves, prosthetic heart valves, acute coronary syndrome, stroke, hemodynamic instability, hospital admissions or surgical interventions within the preceding 6 months. MAIN MEASURES: SFMC levels were measured in plasma by immunoturbidimetry in an automated coagulometer (STALiatestFM, Diagnostica Stago, Asnieres, France). KEY RESULTS: We recorded 121 (1.52%/year) ischemic strokes, 257 (3.23%/year) cardiovascular events, 67 (0.84%/year) cardiovascular deaths and 486 (6.10%/year) all-cause deaths. SFMC >12 µg/mL was not associated with stroke but was associated with higher risk of cardiovascular events (HR 1.72, 95% CI 1.31-2.26), cardiovascular mortality (HR 2.16, 95% CI 1.30-3.57) and all-cause mortality (HR 1.26, 95% CI 1.03-1.55). When SFMC >12 µg/mL was added to the CHA2DS2-VASc, there were significant improvements in predictive performance, sensitivity and reclassification for adverse cardiovascular events (c-index: 0.645 vs. 0.660, p = 0.010; IDI = 0.013, p < 0.001; NRI = 0.121, p < 0.001) and cardiovascular mortality (c-index: 0.661 vs. 0.691, p = 0.006; IDI = 0.009, p = 0.049; NRI = 0.217, p < 0.001), but decision curves demonstrated a similar net benefit and clinical usefulness. CONCLUSIONS: In AF patients taking VKAs, high SFMC levels were associated with the risk of adverse cardiovascular events, cardiovascular mortality and all-cause mortality. The addition of SFMC to the CHA2DS2-VASc score improved its predictive performance for these outcomes, but failed to show an improvement in clinical usefulness.