Length of ischemia duration is associated with fibrin film coverage of acute myocardial infarction thrombi.

Background: Coronary artery disease plaque rupture leads to occlusive thrombosis, causing acute myocardial infarction requiring immediate life-saving treatment. The blood clot is supported by a mesh of fibrin fibers that are generated through the polymerization of fibrin. We recently showed that fibrin also produces a film on the surface of blood clots.

Objectives: This study aimed to examine whether fibrin film occurs intravascularly on thrombi from patients with myocardial infarction.

Methods: In this observational study, we recruited 42 patients with acute ST-elevation myocardial infarction and obtained intracoronary thrombi using catheter-guided aspiration thrombectomy. We used a protocol that avoids air contact and immediately fixes the sample upon thrombectomy. Thrombi were analyzed by tiled scanning electron micrographs to analyze percentage coverage by fibrin film.

Results: We found that all thrombi showed surface areas covered with fibrin film. Some film coverage was discontinuous. Total film coverage was on average 24.1% ± 17.0% (range, 4.6%-77.2%). Percentage of film coverage correlated positively with the time from onset of symptoms to thrombectomy (ischemia duration) and negatively with in vitro clot formation time. Discontinuous film did not correlate with plasmin generation.

Conclusion: These findings show that fibrin film is an integral structural feature that covers around one-quarter of the surface of all coronary thrombi and that older thrombi contain more film. This new structure on thrombi may have important implications for clot contraction, resistance to thrombolysis, and mechanical clot extraction.