Coagulation activity and emboli counts in patients with prosthetic cardiac valves

Background and Purpose: The underlying embolic material detected by transcranial Doppler ultrasound in patients with prosthetic heart valves remains unknown. We undertook this study to evaluate the relation between the number of Doppler emboli signals and the activity of the coagulation system. Methods: Patients with various types of prosthetic valves (n = 120) and patients in atrial fibrillation (n = 20) were monitored for 30 minutes using transcranial Doppler with a 2-MHz probe. The plasma concentrations of cross-linked D-dimer, antithrombin-III, and thrombin-antithrombin III complex were measured. Results: No correlation between the levels of any of the hematologic parameters and the number of emboli was demonstrated in the studied groups. The D-dimer levels were significantly higher in patients with mechanical prosthetic valves with an international normalized ratio under 2.0 compared with those with an international normalized ratio between 2 and 3.5 or above 3.5, and in patients with Medtronic-Hall versus Björk-Shiley or Carpentier-Edwards valve prostheses. Conclusions: The lack of correlation between the activity of the coagulation system and the number of Doppler emboli in patients with prosthetic valves suggests that the underlying embolic material in these patients is not thrombotic. Our results also suggest that an increase of the anticoagulation intensity to an international normalized ratio above 3.5 does not result in a further decrease of the activity of the unstimulated coagulation system in patients with mechanical prosthetic valves