Tissue factor pathway inhibitor is an early biomarker of myocardial injury in patients with ST-segment elevation acute myocardial infarction

Glycative and oxidative stress are associated with altered thrombus composition in diabetic patients with ST-elevation myocardial infarction

BACKGROUND

The role of type 2 diabetes (T2DM) on composition of thrombus has not been fully characterized in patients with ST-elevation myocardial infarction (STEMI).

AIMS

To elucidate the differences between diabetic and non-diabetic patients with STEMI in relation to the composition of coronary thrombus, and the potential association of these differences with glycated haemoglobin levels and markers of oxidative stress.

METHODS

Intracoronary thrombi from consecutive thrombus aspiration procedures in STEMI patients, 25 diabetic and 28 non-diabetic, were analyzed by immunofluorescence with confocal microscopy. Plasma biomarkers (P-selectin, vWF, PAI-1, t-PA, D-dimer, TF pathway markers, plasmin and CD34⁺) were measured in peripheral blood, and the oxidative capacity of plasma as indirect measure of oxidative stress was measured in parallel.

RESULTS

Patients with T2DM had higher levels of fibrin (P=0.03), P-selectin (P=0.0001), PAI-1 (P=0.03) and vWF (P=0.006) in the thrombus and higher plasma TF activity (P=0.01) compared to non-diabetics. TF activity and plasmin correlated with HbA₁C levels (R²=0.71, P=0.0001; R²=0.46, P=0.04, respectively) and TF was inversely correlated with TFPI (R²=-0.44, P=0.008) and tPA (R²=-0.48, P=0.003). Diabetic patients showed a higher oxidative response of plasma (26.47±6.88% vs 22.06±6.96% of oxidized lipids, P=0.04) (measured by H-NMR spectroscopy) that was associated to increased fibrin content into thrombus (R²=0.76, P=0.01).

CONCLUSION

Diabetic patients with STEMI display an increased thrombogenicity that results in a different thrombus composition respect to non-diabetic patients with STEMI. The increased thrombogenicity present in T2DM is related to higher glycoxidative stress, as quantified by HbA₁C levels and oxidative response in plasma.

Increased von Willebrand factor, P-selectin and fibrin content in occlusive thrombus resistant to lytic therapy

Therapeutic fibrinolysis is ineffective in 40 % of ST-segment elevation acute myocardial infarction (STEMI) patients, but understanding of the mechanisms is incomplete. It was our aim to compare the composition of coronary thrombus in lysis-resistant STEMI patients with that of lysis-sensitive patients. Intracoronary thrombi (n=64) were obtained by aspiration in consecutive STEMI patients. Of them, 20 had received fibrinolysis and underwent rescue percutaneous coronary intervention (r-PCI, lysis-resistant patients) and 44 underwent primary PCI (p-PCI). Lysis-sensitivity was determined in vitro by clot permeability measurements and turbidimetric lysis in plasma of 44 patients undergoing p-PCI and 20 healthy donors. Clot-lysis sensitivity was defined as a clot-lysis time not greater than 1 SD over the mean of healthy donors. Coronary thrombus composition in 20 lysis-resistant and in 20 lysis-sensitive patients was analysed by immunofluorescence with confocal microscopy. Plasma biomarkers (P-selectin, VWF, PAI-1, t-PA, D-dimer, TF pathway markers, plasmin and CD34+) were measured simultaneously on peripheral blood. Lysis-resistant clots had higher levels of fibrin (p=0.02), P-selectin (p=0.03) and VWF (p=0.01) than lysis-sensitive clots. Among thrombi obtained ≤ 6 hours after onset of symptoms, those from lysis-resistant patients showed a higher content in fibrin than those from p-PCI patients (p=0.01). Plasma PAI-1 (p=0.02) and D-dimer levels were significantly higher (p=0.003) in lysis-resistant patients, whereas plasmin levels were lower (p=0.03). Multivariate analysis showed the content of fibrin and VWF within thrombus as predictors of thrombolysis resistance. In conclusion, coronary thrombi in STEMI patients resistant to fibrinolysis are characterised by higher fibrin, P-selectin and VWF content than lysis-sensitive thrombi.