Association of Soluble CD40 Ligand With Duration of Atrial Fibrillation and With Intensity of Spontaneous Echocardiographic Contrast

Objectives The authors tested the hypothesis that the inflammatory response of nonvalvular atrial fibrillation (NVAF) is associated with elevated soluble CD40 ligand (sCD40L). Background NVAF is generally believed to be an inflammatory disease process. sCD40L represents a sensitive in vivo indicator of platelet activation and may serve as an “inflammatory and thrombotic thermometer.” Methods Plasma sCD40L was measured using enzyme-linked immunoadsorbent assay in 109 NVAF cases (60.9 ± 15 years of age; 26% women) and 48 normal sinus rhythm (NSR) controls (62.3 ± 15 years of age; 44% women). Patients were separated by arrhythmia duration of <1 month (n = 21), 1 to 12 months (n = 18), and >12 months (n = 70). Results Median sCD40L level was significantly higher in NVAF cases than in NSR controls (321 pg/ml vs. 238 pg/ml, respectively; p = 0.029). This difference was driven by higher levels in patients with NVAF duration for <1 month (552 pg/ml) and 1 to 12 months (328 pg/ml). NVAF patients with arrhythmia duration for over 1 year had sCD40L levels not significantly different from those of NSR controls. An sCD40L concentration of 552 pg/ml distinguished NVAF patients with dysrhythmia duration of <1 month (area under the curve [AUC] of 0.72; p = 0.0010) or duration for ≤12 months (AUC: 0.69; p = 0.0003) from NSR controls. Circulating sCD40L levels were also significantly higher among patients with mild spontaneous echocardiogram contrast (SEC) (p = 0.0378) and those with moderate SEC (p = 0.007) compared with NSR controls. Conclusions sCD40L levels are significantly higher in NVAF patients than in NSR controls but only for up to 1 year after development of dysrhythmia. An sCD40L concentration of 552 pg/ml can help to assess development or recurrence of asymptomatic NVAF.