Thrombotic microangiopathy

Pulmonary involvement in catastrophic antiphospholipid syndrome: A descriptive analysis from the "CAPS Registry"

OBJECTIVES

To describe the pulmonary involvement in patients with catastrophic antiphospholipid syndrome (CAPS), focusing on its relationship with extrapulmonary involvement, laboratory, radiological, and pathological findings.

METHODS

This retrospective cross-sectional study includes all patients grouped in the "CAPS Registry". All cases were reviewed, and those with pulmonary thromboembolism (PE) and/or diffuse alveolar hemorrhage (DAH) were selected. Data on pulmonary and extrapulmonary clinical presentation, radiologic patterns, laboratory findings, associated autoimmune diseases, treatments, and outcomes were analyzed. Frequency distribution and measures of central tendency were used to describe the cohort. Comparison between groups regarding qualitative variables was undertaken by chi-square or Fisher exact test, while T-test for independent variables was used to compare groups regarding continuous variables. IBM-SPSS v.22 was used for data analysis.

RESULTS

PE was reported in 129 (48.6 %) episodes, DAH in 75 (28.3 %) episodes, and overlap (DAH plus PE) in 7 (2.6 %) episodes. Bronchoalveolar lavage (BAL) was performed in 35 (4.9 %) CAPS episodes, and lung pathology samples were obtained in 84 (10.5 %) episodes (including autopsies). A significant relationship was observed between DAH and laboratory features of thrombotic microangiopathy (TMA). A meaningful relationship was also found between triple antiphospholipid antibody positivity and pathological TMA (26.5 %) as well as hypocomplementemia and DAH (24 %).

CONCLUSIONS

Pulmonary involvement may include both TMA and non-thrombotic inflammation, which can be differentiated into three patterns: PE, DAH with systemic TMA with hypocomplementemia or DAH without systemic TMA with/without hypocomplementemia.

A Saudi multicenter experience on therapeutic plasma exchange for patients with thrombotic thrombocytopenic purpura: A call for national registry

BACKGROUND

The improvement in the clinical care for patients with thrombotic thrombocytopenic purpura (TTP) is evolving, and many efforts are being put to standardize it. Here, we aimed to assess the provided care at a national level and identify deficiencies.

METHODS

A national Saudi retrospective descriptive study was carried out at six tertiary referral centers and included all patients who underwent therapeutic plasma exchange (TPE) for the diagnosis of TTP between May 2005, and July 2022. Collected information included demographic data, clinical features on presentation, and the results of laboratory investigations at admission and discharge. In addition, the number of TPE sessions, days till the first session of TPE, usage of immunological agents, and clinical outcomes were all collected.

RESULTS

One hundred patients were enrolled, predominantly female (56%). The mean age was 36.8 years. At diagnosis, 53% of patients showed neurological involvement. The mean platelet count at presentation was 21 × 109 /L. All patients had anemia (mean hematocrit 24.2%). Schistocytes were present in the peripheral blood film of all patients. The mean number of TPE rounds was 13 ± 9.3, and the mean days to start TPE since admission for the first episode was 2.5 days. ADAMTS13 level was measured in 48% of patients and was significantly low in 77% of them. Assessing for clinical TTP scores, 83%, 1000%, 64% of eligible patients had an intermediate/high PLASMIC, FRENCH, and Bentley scores, respectively. Caplacizumab was used on only one patient, and rituximab was administered to 37% of patients. A complete response for the first episode was achieved in 78% of patients. The overall mortality rate was 25%. Neither time to TPE, the use of rituximab or steroid affected survival.

CONCLUSIONS

Our study shows an excellent response to TPE with a survival rate approximate to the reported international literature. We observed a deficiency in using validated scoring systems in addition to confirming the disease by ADAMTS13 testing. This emphasizes the need for a national registry to facilitate proper diagnosis and management of this rare disorder.

Comparison of Clinical Scoring Systems in the Management of Patients with Microangiopathic Hemolytic Anemia and Thrombocytopenia

Objective:

Several clinical scoring systems have been developed for the differential diagnosis of thrombotic microangiopathies (TMAs), all to predict and identify patients with ADAMTS13 deficiency and to start treatment as soon as possible. The first scoring system in this regard was the Bentley score, and the French score and PLASMIC score were developed afterwards.

Materials and Methods:

We aimed to evaluate the laboratory parameters and clinical features of patients who underwent plasma exchange with a prediagnosis of TTP at our clinic between 2007 and 2019 and whose ADAMTS13 enzyme levels were measured and to compare the findings with the scoring systems.

Results:

Data of 35 patients were evaluated. Twelve patients were evaluated as high risk according to all three scoring systems. A statistically significant relation was observed between all three scoring systems and ADAMTS13 levels.

Conclusion:

A moderate correlation was found between all three scoring systems and ADAMTS13 levels. We observed similar potential strength of all three scoring systems to predict TTP among other TMAs and we conclude that they are applicable in daily practice.

Thrombalexin: Use of a Cytotopic Anticoagulant to Reduce Thrombotic Microangiopathy in a Highly Sensitized Model of Kidney Transplantation

Early activation of coagulation is an important factor in the initiation of innate immunity, as characterized by thrombotic microangiopathy (TMA). In transplantation, systemic anticoagulation is difficult due to bleeding. A novel "cytotopic" agent, thrombalexin (TLN), combines a cell-membrane-bound (myristoyl tail) anti-thrombin (hirudin-like peptide [HLL]), which can be perfused directly to the donor organ or cells. Thromboelastography was used to measure time to clot formation (r-time) in both rhesus and human blood, comparing TLN versus HLL (without cytotopic tail) versus negative control. Both TLN- and HLL-treated rhesus or human whole blood result in significantly prolonged r-time compared to kaolin controls. Only TLN-treated human endothelial cells and neonatal porcine islets prolonged time to clot formation. Detection of membrane-bound TLN was confirmed by immunohistochemistry and fluorescence activated cell sorter. In vivo, perfusion of a nonhuman primate kidney TLN-supplemented preservation solution in a sensitized model of transplantation demonstrated no evidence of TLN systemically. Histologically, TLN was shown to be present up to 4 days after transplantation. There was no platelet deposition, and TMA severity, as well as microvascular injury scores (glomerulitis + peritubular capillaritis), were less in the TLN-treated animals. Despite promising evidence of localized efficacy, no survival benefit was demonstrated.

Analyses of data of patients with Thrombotic Microangiopathy in the WAA registry

Thrombotic Microangiopathy (TMA) is a histopathological feature of various diseases including thrombotic thrombocytopenic purpura and hemolytic uremic syndrome. The aim of this study was to investigate the outcome and prognostic variables of TMA-patients.

MATERIALS AND METHODS

Data were consecutively retrieved from the WAA-apheresis registry (www.waa-registry.org) during 2003-2009. Included were all 120 patients (1237 procedures) who suffered from various forms of TMA, as registered by the ICD-10 code M31.1. Besides registry data, more extensive information was retrieved from the latest 64 patients. Adverse events of the TMA patients were compared to those of the other patients in the registry.

RESULTS

The mean age was 46 years (range 11-85 years, 57% women). In 72% therapeutic apheresis was due to an acute indication while a long-term indication was present in 28%. Plasma exchange was performed by centrifugation and filtration technique (95% and 4%, respectively), and immunoadsorption in 1% of the patients. Only fresh frozen plasma was used as replacement fluid in 69% of procedures. Adverse events were more frequent than in the general apheresis population (10% versus 5%, RR 1.9, CI 1.6-2.3). No death occurred due to apheresis treatment. Three percent of the procedures were interrupted. Bronchospasm and/or anaphylactic shock were present in two patients and one patient suffered from TRALI. At admission 26% were bedridden and needed to be fed. The risk of dying during the treatment period was significantly higher if the patient also suffered from a compromising disease, such as cancer. There was an inverse correlation between the ADAMTS13 level and the antibody titer (r=-0.47, p=0.034).

CONCLUSIONS

Patients with TMA have an increased risk for moderate and severe AE compared to the general apheresis population. Many patients were severely ill at admission. The prognosis is worse if the patient also has a severe chronic disease. Even slightly increased ADAMTS13-antibody titers seem to have a negative impact on the ADAMTS13 levels.