The Official Journal of EuroPCR and the European Association of Percutaneous Cardiovascular Interventions (EAPCI)

Objectives— We sought to investigate whether patients with in-stent thrombosis (IST) display altered plasma fibrin clot properties. Methods and Results— We studied 47 definite IST patients, including 15 with acute, 26 subacute and 6 late IST, and 48 controls matched for demographics, cardiovascular risk factors, concomitant treatment and angiographic/stent parameters. Plasma clot permeability (K_s), which indicates a pore size, turbidity (lag phase, indicating the rate of fibrin clot formation, ΔAbs_max, maximum absorbance of a fibrin gel, reflecting the fiber thickness), lysis time (t_50%) and maximum rate of d-dimer release from clots (D-D_rate) were determined 2 to 73 (median 14.7) months after IST. Patients with IST had 21% lower K_s, 14% higher ΔAbs_max, 11% lower D-D_rate, 30% longer t_50% (all P<0.0001) and 5% shorter lag phase compared to controls (P=0.042). There were no correlations between clot variables and the time of IST or that from IST to blood sampling. Multiple regression analysis showed that K_s (odds ratio=0.36 per 0.1 μm², P<0.001), D-D_rate (odds ratio=0.16 per 0.01 mg/L/min, P<0.001) and stent length (odds ratio=1.1 per 1 mm, P=0.043) were independent predictors of IST (R²=0.58, P<0.001). Conclusions— IST patients tend to form dense fibrin clots resistant to lysis, and altered plasma fibrin clot features might contribute to the occurrence of IST. Plasma fibrin clot properties were assessed in patients after in-stent thrombosis (IST). Our findings suggest that altered fibrin clot features associated with attenuated fibrinolysis can be detected in patients with IST. Reduced clot permeability and susceptibility to lysis represent a novel prothrombotic mechanism, which might contribute to the IST.

Determinants of intracoronary thrombus (ICT) composition in patients with ST-elevation myocardial infarction (STEMI) are largely unknown. We sought to investigate whether plasma fibrin phenotype and platelet reactivity affect ICT ultrastructure. We assessed the content of fibrin, platelets and erythrocytes including polyhedrocytes by scanning electron microscopy on the surface and inside ICT aspirated from 80 STEMI patients within 12 hours since chest pain onset. Plasma fibrin clot permeability (K_s), which indicates the average pore size, lysis time (t_{50 %}), platelet reactivity index (PRI) and ADP-induced platelet aggregation (ADP_5,20μM) were evaluated on admission. All patients received aspirin and 45 (56.3 %) 600 mg of clopidogrel, 80 (60–120) min prior to aspiration. Higher content of fibrin (61.6 vs 34.3 %, P< 0.0001) and platelets (8.2 vs 4.8 %, P=0.018) and lower erythrocyte content (15.8 vs 42.9 %, P< 0.0001) were found on ICT surface compared with its inner part. After adjustment for fibrinogen, in both ICT parts fibrin content was correlated with K_s (r≤-0.55, P< 0.0001) and t_50% (r≥ 0.29, P≤ 0.02) but not with PRI and ADP_5,20μM. Polyhedrocytes were observed in 16 (20 %) patients and their large amount expressed as ≥ 50 % fields of view covered by polyhedrocytes was associated with the lower PRI values (40 vs 69 %, P=0.015), but not K_s or t_50%. By multivariate regression, K_s (β=-0.62, P< 0.0001), clopidogrel pretreatment (β=-0.36, P< 0.001), ischemia time (β=0.19, P=0.044) and family history (β=0.18, P=0.049) independently predicted fibrin content in the whole ICT (R²=0.65, P< 0.0001). Formation of denser plasma fibrin clots is independently associated with high fibrin content within the ICT in STEMI.

Myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA) is an important clinical problem especially in the era of extensive utilization of coronary angiography in MI patients. Its pathophysiology is poorly understood which makes diagnostics and treatment of MINOCA challenging in everyday clinical practice. The aim of the study was to assess characteristics of MINOCA patients in Poland based on data from the Polish National ORPKI Registry. In 2016, 49,893 patients with non-ST-segment elevation (NSTEMI) or ST-segment elevation (STEMI) myocardial infarction entered the ORPKI registry. MINOCA was defined as a non-obstructive coronary artery disease (CAD) and a lack of previous coronary revascularization. MINOCA was identified in 3924 (7.8%) patients and clinical presentation was more often NSTEMI than STEMI (MINOCA: 78 vs. 22%; obstructive CAD 51.1 vs. 48.9%; p < 0.0001). MINOCA patients were younger and more often females with significantly lower rates of diabetes, smoking, arterial hypertension, kidney disease, previous MI and previous stroke comparing to patients with obstructive CAD. Myocardial bridge was visualized in angiography more often in the MINOCA group (2.2 vs. 0.4%; p < 0.0001). Additional coronary assessment inducing fractional flow reserve, intravascular ultrasound, optical coherence tomography was marginally (< 1%) used in both groups. Periprocedural mortality was lower in MINOCA group (0.13% vs. 0.95%; p < 0.0001). MINOCA patients represent a significant proportion of MI patients in Poland. Due to multiple potential causes, MINOCA should be considered rather as a working diagnosis after coronary angiography and further efforts should be taken to define the cause of MI in each individual patient.