Hypercoagulability, D-dimer and atrial fibrillation: an overview of biological and clinical evidence.

Atrial fibrillation (AF) is the most common among the severe cardiac arrhythmias and carries a significant risk of mortality and morbidity in the general population. The most important complication is represented by development of one or more thrombi in the left atrium of the dyskinetic heart, and their successive cerebral and peripheral embolization. The pathophysiological basis of the thromboembolic complications in AF entails the presence of a hypercoagulable state, which is mirrored by increased concentrations of a variety of prothrombotic markers. D-dimer is universally considered the gold standard among the various biomarkers that reflect activation of coagulation, fibrinolysis, or both, and several studies have assessed its diagnostic and prognostic role in AF. With a few exceptions and despite a broad heterogeneity in the study designs, published data seem to demonstrate that D-dimer values may be associated with the presence of atrial thrombosis, may be predictive of primary adverse outcomes and death, may be correlated with cerebral infarction volume, and may also be a useful parameter for assessing the degree of hypercoagulability of AF patients after cardioversion. If larger prospective studies confirm these findings, D-dimer assessment may hence become an integral part of the clinical decision-making in patients with AF.