No-reflow phenomenon after acute myocardial infarction is associated with reduced clot permeability and susceptibility to lysis

Objective-We assessed the relationship between fibrin clot properties and the no-reflow phenomenon after primary coronary intervention (PCI). Methods and Results-Epicardial blood flow was assessed by TIMI scale and corrected TIMI frame count (cTFC), and perfusion by TIMI Myocardial Perfusion Grade ( TMPG) after PCI during ST-segment elevation myocardial infarction (STEMI). Fibrin clot permeability (K-s)and susceptibility to lysis in assays using exogenous thrombin (t(50%)) and without thrombin (t(TF)) were determined in 30 no-reflow patients (TIMI <= 2) and in 31 controls (TIMI-3) after uneventful 6 to 14 months from PCI. Patients with TIMI <= 2 had lower Ks by 18% (P < 0.0001) and prolonged fibrinolysis by 33% for t(50%) (P < 0.0001) and by 45% for tTF (P < 0.0001). cTFC was correlated with Ks (r= -0.56, P < 0.0001), t(50%) (r=0.49, P < 0.001), and t(TF) (r < 0.54, P < 0.001). K-s increased in a stepwise fashion with TIMI flow (P < 0.0001) and TMPG (P < 0.0001), whereas both fibrinolysis times decreased with TIMI flow (P < 0.0001 for both) and TMPG (P < 0.01 for both). Multiple regression models showed that only K-s and fibrinogen were independent predictors of cTFC (P < 0.05 for both), TIMI <= 2 flow (P < 0.05 for both) and TMPG-0/1 (P < 0.05 for both). Conclusions-Survivors of myocardial infarction with a history of the no-reflow after PCI are characterized with more compact fibrin network and its resistance to lysis.