Prognostic risk-stratified score for predicting mortality in hospitalized patients with thrombotic thrombocytopenic purpura: nationally representative data from 2007 to 2012

MINOCA as the result of coronary artery aneurysm thrombosis

Myocardial infarction (MI) can be caused by many factors. In addition to the typical obstruction or stenosis of the coronary arteries, there is heterogenic MI with non-obstructive coronary arteries (MINOCA). A rare cause of MINOCA is the thrombosis of a coronary artery aneurysm (CAA). This current case report describes a male patient with CAA thrombosis as the cause of MINOCA following surgery for a mucoepidermoid carcinoma. The patient underwent angiography that identified three CAAs that were located as follows: (i) in the proximal part of the left anterior descending artery (5.55 mm); (ii) in the distal part of the circumflex artery (8.05 mm); and (iii) in the distal part of the right coronary artery (6.61 mm). Thrombotic masses were identified within all three structures. The patient received balloon angioplasties without stent implanting and recovered well. The patient was also notable for the presence of two brain artery aneurysms that were the cause of the previous strokes that he had experienced. This case report also reviews the literature in order to: (i) summarize the aetiological factors and clinical manifestations of CAA; (ii) discuss the diagnostic methods for CAA; (iii) describe the medical and surgical management of CAA; and (iv) assess the prognosis of this rare clinical event.

[100 years thrombotic thrombocytopenic purpura (TTP) - lessons learned?]

100 years ago Dr. Eli Moschcowitz described the first case of thrombotic thrombocytopenic purpura. For many decades there were no recognized treatment options, and the mortality rate was extremely high. At the beginning of the 1990 s, therapy with steroids and plasma exchange became increasingly popular, although the mortality rate was still over 20 %. It took until the turn of the millennium for the disease mechanisms (ADAMTS13-deficiency) to be decoded in Bern and New York, thus paving the way for new therapy options. It has now become clear that acquired TTP (iTTP) is an autoimmune disease, and the autoantibodies are directed against ADAMTS13, a protease that cleaves large von-Willebrand multimers. This causes a severe ADAMTS13-deficiency. The ultralarge multimers persist and bind platelets, resulting in microvascular thrombosis. This is distinguished from congenital TTP (cTTP), in which severe ADAMTS13-deficiency is caused by mutations in the ADAMTS13-gene (Upshaw-Schulman syndrome). In other forms of thrombotic microangiopathy (TMA, e. g. aHUS), severe ADAMTS13-deficiency does not occur. Two randomized controlled studies demonstrated the benefit of the selective bivalent anti-von-Willebrand factor (vWF) nanobody Caplacizumab, approved in 2019, in the treatment of iTTP. Various publications from national iTTP cohorts improved the data and showed consistent reductions in the time until platelet normalization, a reduction in refractory courses and exacerbations (especially when therapy is controlled according to ADAMTS13-activity) as well as evidence of reduced mortality. Modern therapeutic options include strategies for preemptive therapy for ADAMTS13-relapse as well as plasma exchange-free treatment. The use of recombinant ADAMTS13 may also expand the therapeutic options in iTTP patients in the future.

Coronary artery thromboembolism as a cause of myocardial infarction with non-obstructive coronary arteries (MINOCA)

Acute myocardial infarction (AMI) usually represents the clinical manifestation of atherothrombotic coronary artery disease (CAD) resulting from atherosclerotic plaque rupture. However, there are cases in which coronary angiography or coronary computed tomography angiography reveals patients with acute coronary syndrome with non-obstructive CAD. This clinical entity is defined as myocardial infarction with non-obstructive coronary arteries (MINOCA) and often considered as a clinical dynamic working diagnosis that needs further investigations for the establishment of a final etiologic diagnosis. The main causes of a MINOCA working diagnosis include atherosclerotic, non-atherosclerotic (vessel-related and non-vessel-related), and thromboembolic causes This literature review aimed to investigate the major thromboembolic causes in patients presenting with MINOCA regarding their etiology and pathophysiologic mechanisms, as well as diagnostic and treatment methods.

A machine learning approach to predict mortality due to immune-mediated thrombotic thrombocytopenic purpura

Background

Mortality due to immune-mediated thrombotic thrombocytopenic purpura (iTTP) remains significant. Predicting mortality risk may potentially help individualize treatment. The French Thrombotic Microangiopathy (TMA) Reference Score has not been externally validated in the United States. Recent advances in machine learning technology can help analyze large numbers of variables with complex interactions for the development of prediction models.

Objectives

To validate the French TMA Reference Score in the United States Thrombotic Microangiopathy (USTMA) iTTP database and subsequently develop a novel mortality prediction tool, the USTMA TTP Mortality Index.

Methods

We analyzed variables available at the time of initial presentation, including demographics, symptoms, and laboratory findings. We developed our model using gradient boosting machine, a machine learning ensemble method based on classification trees, implemented in the R package gbm.

Results

In our cohort (n = 419), the French score predicted mortality with an area under the receiver operating characteristic curve of 0.63 (95% CI: 0.50-0.77), sensitivity of 0.35, and specificity of 0.84. Our gradient boosting machine model selected 8 variables to predict acute mortality with a cross-validated area under the receiver operating characteristic curve of 0.77 (95% CI: 0.71-0.82). The 2 cutoffs corresponded to sensitivities of 0.64 and 0.50 and specificities of 0.76 and 0.87, respectively.

Conclusion

The USTMA Mortality Index was acceptable for predicting mortality due to acute iTTP in the USTMA registry, but not sensitive enough to rule out death. Identifying patients at high risk of iTTP-related mortality may help individualize care and ultimately improve iTTP survival outcomes. Further studies are needed to provide external validation. Our model is one of many recent examples where machine learning models may show promise in clinical prediction tools in healthcare.

Should we consider caplacizumab as routine treatment for acute thrombotic thrombocytopenic purpura? An expert perspective on the pros and cons

INTRODUCTION

Immune thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening disorder. Caplacizumab has been the latest drug incorporated into the initial treatment of acute episodes, allowing for faster platelet recovery and a decrease in refractoriness, exacerbation, thromboembolic events, and mortality. However, caplacizumab is also associated with a bleeding risk and higher treatment costs, which prevent many centers from using it universally.

AREAS COVERED

Studies that included iTTP and/or caplacizumab to date were selected for this review using PubMed and MEDLINE platforms. We describe outcomes in the pre-caplacizumab era and after it, highlighting the benefits and risks of its use early in frontline, and also pointing out special situations that require careful management.

EXPERT OPINION

It is clear that the availability of caplacizumab has significantly and favorably impacted the management of iTTP patients. Whether this improvement is cost-effective still remains uncertain, and data on long-term sequelae and different healthcare systems will help to clarify this point. In addition, evidence of the bleeding/thrombotic risk of iTTP patients under this drug needs to be better addressed in future studies.

Immune thrombotic thrombocytopenic purpura in older patients: Results from the Spanish TTP Registry (REPTT)

Immune thrombotic thrombocytopenic purpura (iTTP) is an ultra-rare disease that seldom occurs in the elderly. Few reports have studied the clinical course of iTTP in older patients. In this study, we have analysed the clinical characteristics at presentation and response to therapy in a series of 44 patients with iTTP ≥60 years at diagnosis from the Spanish TTP Registry and compared them with 209 patients with <60 years at diagnosis from the same Registry. Similar symptoms and laboratory results were described in both groups, except for a higher incidence of renal dysfunction among older patients (23% vs. 43.1%; p = 0.008). Front-line treatment in patients ≥60 years was like that administered in younger patients. Also, no evidence of a difference in clinical response and overall survival was seen in both groups. Of note, 14 and 25 patients ≥60 years received treatment with caplacizumab and rituximab, respectively, showing a favourable safety and efficacy profile, like that observed in patients <60 years.

A British Society for Haematology Guideline: Diagnosis and management of thrombotic thrombocytopenic purpura and thrombotic microangiopathies

The objective of this guideline is to provide healthcare professionals with clear, up-to-date and practical guidance on the management of thrombotic thrombocytopenic purpura (TTP) and related thrombotic microangiopathies (TMAs), including complement-mediated haemolytic uraemic syndrome (CM HUS); these are defined by thrombocytopenia, microangiopathic haemolytic anaemia (MAHA) and small vessel thrombosis. Within England, all TTP cases should be managed within designated regional centres as per NHSE commissioning for highly specialised services.

Cardiovascular Disease and Stroke in Immune TTP-Challenges and Opportunities

Advances in the management of immune thrombotic thrombocytopenic purpura (iTTP) have dramatically improved outcomes of acute TTP episodes, and TTP is now treated as a chronic, relapsing disorder. It is now recognized that iTTP survivors are at high risk for vascular disease, with stroke and myocardial infarction occurring at younger ages than in the general population, and cardiovascular disease is the leading cause of premature death in this population. iTTP appears to have a phenotype of accelerated vascular aging with a particular predilection for cerebral circulation, and stroke is much more common than myocardial infarction. In addition to traditional cardiovascular risk factors, low ADAMTS13 activity during clinical remission may be a risk factor for some of these outcomes, such as stroke. Recent studies also suggest that Black patients, who are disproportionately affected by iTTP in the United States, are at higher risk of adverse cardiovascular outcomes, likely due to multifactorial reasons. Additional research is required to establish the risk factors and mechanisms underlying these complications in order to institute optimal screening strategies and identify interventions to improve outcomes.

Quantitative analysis of external carotid artery bypass donor vessels by recipient and approach

INTRODUCTION

Utilization an in-situ pedicle of the external carotid artery (ECA) as an arterial donor can allow for the successful augmentation or replacement of flow to a large vascular territory. We propose a mathematical model for quantitatively analyzing and grading the suitability of donor and recipient bypass vessels based on a set of anatomical and surgical variables in order to predict which pair has the greatest possibility for success. Using this method, we analyze all of the potential donor-recipient pairs for each ECA donor vessel-including the superficial temporal (STA), middle meningeal (MMA), and occipital (OA) arteries.

METHODS

The ECA pedicles were dissected in frontotemporal, middle fossa, subtemporal, retrosigmoid, far lateral, suboccipital, supracerebellar, and occipital transtentorial approaches. For each approach, every potential donor-recipient pair was identified, and donor length and diameter were measured as well as depth of field, angle of exposure, ease of proximal control, maneuverability, and length and diameter of the recipient segment. Anastomotic pair scores were determined by adding the weighted donor and recipient.

RESULTS

The best overall anastomotic pairs were OA-vertebral artery (V3, 17.1) and STA-insular (M2, 16.3) and STA-sylvian (M3, 15.9) segments of the middle cerebral artery. Other strong anastomotic combinations were OA- telovelotonsillar (15) and OA- tonsilomedullary (14.9) segments of the posterior inferior cerebellar artery, and MMA-lateral pontomesencephalic segment of the superior cerebellar artery (14.2).

CONCLUSIONS

This novel model for anastamotic pair scoring can serve as a useful clinical tool for selecting the optimal donor, recipient, and approach combination that can help facilitate a successful bypass.

In patients with suspected immune TTP, admission source impacts hospital length of stay and time to therapeutic plasma exchange impacts clinical outcomes

INTRODUCTION

When immune thrombotic thrombocytopenic purpura (TTP) is suspected, outcomes are impacted by time to therapeutic plasma exchange (TPE). We evaluated the impact of time to TPE on outcomes in suspected TTP cases admitted through the Emergency Department (ED) vs. transferred from another facility (Transfer).

MATERIALS AND METHODS

In a retrospective analysis of the National Inpatient Sample, we examined the association between TTP outcomes and admission source (ED vs. Transfer) for the primary outcome of time to TPE. A second stratified analyses within each analytic group examined the association of time to TPE (<1 day, 1 day, 2 days, and >2 days) and outcomes for the composite outcome of mortality, major bleeding and thrombosis.

RESULTS

Of 1195 cases, 793 (66 %) were admitted through the ED and 402 (34 %) were transferred. Compared to ED cases, Transfers had a longer hospital length of stay (14.69 vs. 16.65 days, p = 0.0060). For ED cases, TPE after >2 days was associated with higher odds of the composite outcome (OR = 1.68 95 % CI: 1.11-2.54; p = 0.0150) and mortality (OR = 3.01 95 % CI: 1.38-6.57; p = 0.0056). For Transfers, TPE on day 2 was associated with higher odds of the composite outcome (OR = 3.00 95 % CI: 1.31-6.89; p = 0.0096) and mortality (OR = 4.95 95 % CI: 1.12-21.88; p = 0.0350).

CONCLUSIONS

In suspected TTP admitted through the ED or transferred, there was no significant difference in time to TPE. A longer time to TPE was associated with worse outcomes. Future studies should evaluate strategies to decrease initial time to TPE.

A second look at the mortality in thrombotic thrombocytopenic purpura score: An external validation study

BACKGROUND

Despite high effectiveness of therapeutic plasma exchange as the first-line therapy, thrombotic thrombocytopenic purpura (TTP) remains a life-threatening condition and may require utilization of adjunct modalities in certain patients. Mortality In TTP Score (MITS) is a prognostic risk stratified scoring tool designed to predict mortality in hospitalized patients with TTP. There has not been an external validation of MITS to date.

STUDY DESIGN AND METHODS

We performed an external validation of MITS in patients hospitalized with TTP using the National Inpatient Sample database from 2016 to 2019. We identified 4589 patients who met the selection criteria. Univariate and multivariable logistic regression models were run based on the MITS parameters of arterial thrombosis, intracranial haemorrhage, age, renal failure, ischemic stroke, platelet transfusion, and myocardial infarction to evaluate prognostic performance and discriminatory power of this tool.

RESULTS

All-cause mortality was reported more frequently in female subjects (57.8%), Caucasian race (58.9%), and ages 60 years, and above (52.3%). In a multivariable analysis, the variables included in the MITS criteria remained significant predictors of mortality. Moreover, MITS correlated with mortality risk. Our model's area under the receiving operator character curve was 71%, compared to 78.6% in the derivation cohort study.

DISCUSSION

In this external validation cohort, performance of MITS was similar to the derivation cohort, validating it as a valuable clinical tool that may guide management of TTP patients.

Coronary functional assessment in non-obstructive coronary artery disease: Present situation and future direction

Non-obstructive coronary artery disease (CAD), which is defined as coronary stenosis <50%, has been increasingly recognized as an emerging entity in clinical practice. Vasomotion abnormality and coronary microvascular dysfunction are two major mechanisms contributing to the occur of angina with non-obstructive CAD. Although routine coronary functional assessment is limited due to several disadvantages, functional evaluation can help to understand the pathophysiological mechanism and/or to exclude specific etiologies. In this review, we summarized the potential mechanisms involved in ischemia with non-obstructive coronary arteries (INOCA) and myocardial infarction with non-obstructive coronary arteries (MINOCA), the two major form of non-obstructive CAD. Additionally, we reviewed currently available functional assessment indices and their use in non-obstructive CAD. Furthermore, we speculated that novel technique combined anatomic and physiologic parameters might provide more individualized therapeutic choice for patients with non-obstructive CAD.

Epidemiology, treatment patterns, clinical outcomes, and disease burden among patients with immune-mediated thrombotic thrombocytopenic purpura in the United States

Background

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a life-threatening thrombotic microangiopathy. Due to its rarity, epidemiology and real-world outcomes data are scarce.

Objectives

The aim was to assess epidemiology, treatment patterns, clinical outcomes, and disease burden in patients with iTTP in the United States.

Methods

This longitudinal, retrospective observational study of the Optum-Humedica database included patients with an iTTP diagnosis (≥1 documented ADAMTS13 activity less than 10% or one or more iTTP episodes) from January 2007 to December 2019.

Results

Of 666 patients with an iTTP diagnosis between October 2015 and December 2019, 302 (45%) had one or more iTTP episodes. The pooled annual incidence of documented iTTP during this period was 3.43/million, and the annual incidence of one or more iTTP episodes was 1.81/million. Patients with one or more iTTP episodes received a median of six therapeutic plasma exchange (TPE) sessions per episode; 86% received corticosteroids, and 59% received rituximab. Exacerbations occurred in 17% (52/302) and relapse in 11% (34/302); 34% (103/302) had one or more thromboembolic events. Mortality rates during the study period were 25% (167/666) among all patients with iTTP diagnosis, and 14% (41/302) among patients with one or more iTTP episodes. In the assessment of disease burden (January 2007 to September 2019), patients in the iTTP cohort (n = 514) presented with a mean of 14 comorbidities, compared with 3 in a matched non-iTTP cohort (n = 2570). In a cluster analysis, duration of iTTP episode and mortality rate were greater in older versus younger patients.

Conclusions

Despite treatment with TPE and immunosuppressants, patients with iTTP have high risk of morbidity and mortality, demonstrating the need for more effective therapies.

Plasma Levels of Big Endothelin-1 Are Associated with Renal Insufficiency and In-Hospital Mortality of Immune Thrombotic Thrombocytopenic Purpura

Immune thrombotic thrombocytopenic purpura (iTTP) is caused by severe deficiency of plasma ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity. Despite advances in early diagnosis and management, the mortality rate of acute iTTP remains high in a large part of world where access to some of the most novel therapies is limited. To determine the role of plasma big endothelin-1 (bigET-1) or its bioactive product ET-1 as a biomarker and/or a pathogenic factor in acute iTTP, plasma levels of bigET-1 were determined using an immunoassay in patients with iTTP on admission and during remission, as well as in healthy controls; moreover, the biological effect of ET-1 in thrombus formation was determined by a microfluidic assay. We show that plasma levels of bigET-1 were dramatically increased in patients with acute iTTP on admission, which was significantly decreased during clinical response/remission; elevated admission levels of plasma bigET-1 were associated with low estimated glomerular filtration rate, the need for intensive care unit admission or intubation, and in-hospital mortality. Moreover, an addition of a bioactive product ET-1 to cultured endothelial cells in a microfluidic channel significantly accelerated the rate of thrombus formation under arterial flow. Our results demonstrate for the first time a potential role of measuring plasma bigET-1 in patients with acute iTTP in assessing the disease severity and risk of in-hospital mortality, which may help stratify patients for a more aggressive monitoring and therapeutic strategy; also, the bioactive ET-1, derived from bigET-1, may result in acute renal injury in TTP patient, likely through its vasoconstriction and prothrombotic properties.

Severe Thrombotic Thrombocytopenic Purpura (TTP) with Organ Failure in Critically Ill Patients

Thrombotic thrombocytopenic purpura (TTP) is a multiorgan disorder. Organ dysfunction occurs as a consequence of widespread microvascular thrombosis, especially in the heart, brain and kidney, causing transient or partial occlusion of vessels, resulting in organ ischemia. Intensive care unit (ICU) admission varies between 40% and 100% of patients with TTP, either because of severe organ failure or in order to initiate emergency plasma exchange (PEx). Severe neurologic manifestations and cardiac involvement have been associated with higher mortality. Acute kidney injury, although usually less severe than that in hemolytic and uremic syndrome, is common during TTP. Initial management in the ICU should always be considered in TTP patients. The current treatment of TTP in the acute phase is based on urgent PEx, combined with corticosteroid therapy, B-cell-targeted immunotherapy, rituximab and inhibition of the interaction between ultra-large Von Willebrand factor multimers and platelets, using caplacizumab, a monoclonal antibody. ICU management permits close monitoring and the rapid introduction of life-sustaining therapies. This review details the epidemiology of TTP in the ICU, organ failures of critically ill patients with TTP, and the initial management of TTP patients in the ICU.

ADAMTS13 Autoantibodies and Burden of Care in Immune Thrombotic Thrombocytopenic purpura: New Evidence and Future Implications

The introduction Caplacizumab in the management of Immune thrombotic thrombocytopenic purpura (iTTP) has raised different questions, considering its cost-efficacy and the optimal immunosuppressive treatment (IST) to associate. A retrospective multicenter collection of 42 first iTTP cases was conducted to identify variables associated with a higher burden of care and necessity of an implemented IST with early Rituximab (RTX) rescue. A significant correlation resulted between ADAMTS13 inhibitors (ADAMTS13inh) at diagnosis with total plasma exchange (PEXtot) and PEX needed to achieve clinical response (PEXtoCR, r = 0.46; r = 0.48), along with age (r = - 0.31; r = -0.35), platelet count (r = -0.30; r = -0.30), LDH (r = 0.44; r = 0.41) and total bilirubin (r = 0.54; r = 0.35). ADAMTS13inh also correlated with number of days of hospitalization (DoH, r = 0.44). A significant difference was observed in terms of median ADAMTS13inh titer at diagnosis in patient treated with RTX rescue and those responding to only steroid treatment. Thus, ADAMTS13inh titer resulted a marker of iTTP burden of care, associated with higher number of PEXtot, PEXtoCR, DoH and higher probability of needing RTX rescue to achieve clinical response and could be a useful tool for management of new iTTP cases and an interesting variable to optimize iTTP cases stratification in future Caplacizumab cost-efficacy analysis.

[Treatment of immune-mediated thrombotic thrombocytopenic purpura: A decisive turning point]

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening thrombotic microangiopathy characterized by severe deficiency of ADAMTS13, the enzyme that cleaves von Willebrand factor multimers. Recent insights into iTTP pathophysiology have led to the development of new therapies targeting ADAMTS13 replacement, anti-ADAMTS13 antibodies, and von Willebrand factor-platelet interactions. New maximalist therapeutic strategies are emerging based on triple therapy. While plasma exchange remains the cornerstone therapy of the acute phase, the introduction of front-line immunosuppressive treatments, corticosteroids and rituximab, has led to a reduction in exacerbations and relapses but without any significant improvement in survival. Caplacizumab, a bivalent humanized anti-von Willebrand factor nanobody, is poised to revolutionize the treatment of the acute phase. By inhibiting the interaction between von Willebrand factor multimers and platelets, caplacizumab prevents platelets adhesion, prevents the formation of new microthrombi and protects organs from ischemia. Its early combination with plasma exchange and immunosuppressive therapy prevents unfavorable outcomes and reduces the burden of care. Supported by repeated ADAMTS13 assays, rituximab prevents relapse in patients with persistent or recurrent ADAMTS13 deficiency in clinical remission. This review examines how advances in diagnostics and targeted therapies are changing the current treatment paradigm in both the acute and remission phases and are contributing to dramatically improve the iTTP prognosis.

Caplacizumab prevents refractoriness and mortality in acquired thrombotic thrombocytopenic purpura: integrated analysis

The efficacy and safety of caplacizumab in individuals with acquired thrombotic thrombocytopenic purpura (aTTP) have been established in the phase 2 TITAN and phase 3 HERCULES trials. Integrated analysis of data from both trials was conducted to increase statistical power for assessing treatment differences in efficacy and safety outcomes. Caplacizumab was associated with a significant reduction in the number of deaths (0 vs 4; P < .05) and a significantly lower incidence of refractory TTP (0 vs 8; P < .05) vs placebo during the treatment period. Consistent with the individual trials, treatment with caplacizumab resulted in a faster time to platelet count response (hazard ratio, 1.65; P < .001), a 72.6% reduction in the proportion of patients with the composite end point of TTP-related death, TTP exacerbation, or occurrence of at least 1 treatment-emergent major thromboembolic event during the treatment period (13.0% vs 47.3%; P < .001), and a 33.3% reduction in the median number of therapeutic plasma exchange days (5.0 vs 7.5 days) vs placebo. No new safety signals were identified; mild mucocutaneous bleeding was the main safety finding. This integrated analysis provided new evidence that caplacizumab prevents mortality and refractory disease in acquired TTP and strengthened individual trial findings, with a confirmed favorable safety and tolerability profile. These trials were registered at www.clinicaltrials.gov as #NCT01151423 and #NCT02553317.

Elevated plasma levels of syndecan-1 and soluble thrombomodulin predict adverse outcomes in thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a potentially fatal blood disorder resulting from acquired deficiency of plasma ADAMTS13 activity. Despite recent advances in early diagnosis and novel therapeutics, the mortality rate of acute iTTP remains as high as 10% to 20%. Moreover, a reliable clinical and laboratory parameter that predicts disease severity and outcomes is lacking. We show in the present study that plasma levels of syndecan-1 (Sdc-1) and soluble thrombomodulin (sTM) on admission were dramatically increased in patients with acute iTTP and remained substantially elevated in a subset of patients compared with healthy controls. The elevated admission plasma levels of Sdc-1 and sTM were associated with abnormal Glasgow coma scale scores, low estimated glomerular filtration rates, the need for intensive care, and in-hospital mortality rates. Moreover, a further simultaneous increase in plasma Sdc-1 and sTM levels at the time of clinical response/remission (eg, when normalization of platelet counts and substantial reduction of serum lactate dehydrogenase activity were achieved) was highly predictive of iTTP recurrence. These results demonstrate that endothelial injury, resulting from disseminated microvascular thromboses, is severe and persistent in patients with acute iTTP. Plasma levels of Sdc-1 and sTM on admission and in remission are predictive of in-hospital mortality and recurrence of acute iTTP, respectively. Thus, an incorporation of such novel plasma biomarkers into the risk assessment in acute iTTP may help implement a more vigorous and intensive therapeutic strategy for these patients.

Retrospective analysis of bleeding events after central venous catheter placement in thrombotic thrombocytopenic purpura

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic disorder caused by severe deficiency of ADAMTS13. Platelets are transfused prophylactically in non-TTP patients for central venous catheter (CVC) with a count <20 × 10⁹/L to prevent bleeding. However, transfusing platelets in TTP prior to CVC placement remains controversial due to concern for arterial thrombosis and mortality. At our center, platelet transfusion is contraindicated in TTP, therefore, we analyzed data for bleeding complications following CVC placement.

STUDY DESIGN AND METHODS

95 acute episodes of TTP were identified. Twenty-six episodes were excluded for insufficient documentation or no CVC placement. The charts of 69 remaining episodes were reviewed.

RESULTS

Of 69 TTP episodes, nine (13 %) had bleeding after a CVC placement. Of these, seven bleeds were minor, and the two were major related to the technical issues during femoral venous access causing arterial bleeds. Median platelet count before the CVC placement among those experiencing bleeding complications was 12 × 10⁹/L (range 3-44) as compared to median count of 15 × 10⁹/L (range 4-257) in those who did not bleed (p = 0.258). Among 44 episodes with a platelet count <20 × 10⁹/L, seven (16 %) had bleeds.

CONCLUSION

Major bleeding complications following CVC placement in TTP is uncommon and most likely related to technical challenges. Median platelet count was similar in patients who bled versus those who did not, suggesting that platelet transfusion is unnecessary to correct platelet count prior to a CVC placement in TTP.

Application of the French TMA Reference Center Score and the mortality in TTP Score in de novo and relapsed episodes of acquired thrombotic thrombocytopenic purpura at a tertiary care facility in Spain

Acquired thrombotic thrombocytopenic purpura (aTTP) is still associated with a 10% to 20% death rate and its clinical course is characterized by recurrent episodes in up to 50% of cases. Over the last decade, mortality predicting models like the French TMA Reference Center Score and the Mortality In TTP Score (MITS) have been developed in an attempt to personalize treatment. The objective of the present study was to compare the results in both scores of de novo and relapsed aTTP episodes. For such purpose, a total of 29 episodes of aTTP (16 de novo and 13 relapses) were analyzed. All patients were homogeneously diagnosed and treated. First episodes had a higher score in both models in comparison with relapsed aTTP, (MITS median, 1 r: 1-4 vs 0 r: 1-2, P = .038 and French TMA Reference Center Score median, 2 r: 1-3 vs 1 r: 0-1, P = .006). The prevalence of neurological symptoms was significantly higher in the first episodes (P = .001) and patients >60 years old were more common in this group (P = .013), which may have been related to the results. Platelet count at presentation was higher in recurrences than in the first disease episode (P = .016) and ADAMTS13 activity <5% was more frequent in the last group (P = .016). There was no significant difference in the rate of refractoriness or exacerbations. In conclusion, first aTTP episodes had a higher probability of short-term mortality compared to relapsed aTTP episodes according to the MITS and French TMA Reference Center Score.

Cardiovascular Complications and Their Association With Mortality in Patients With Thrombotic Thrombocytopenic Purpura

BACKGROUND

Despite widespread availability of plasmapheresis, the mortality in thrombotic thrombocytopenic purpura remains high. Cardiovascular complications have been reported as an important cause of morbidity in these patients. The burden and prognostic implications of these complications have not been well studied. We analyzed the rates of cardiovascular complications in thrombotic thrombocytopenic purpura, temporal trends, and studied its impact on in-hospital mortality.

METHODS

We analyzed the National Inpatient Sample (NIS) from January 2005 to September 2015 to identify adult patients with thrombotic thrombocytopenic purpura. This group was further refined by excluding patients who did not receive therapeutic plasmapheresis, and other conditions that can mimic thrombotic thrombocytopenic purpura. We identified the age- and sex-stratified rates of cardiac arrhythmias, cardiac conduction system disorders, heart failure, acute coronary syndrome, myocarditis, pericarditis, takotsubo cardiomyopathy, cardiogenic shock, cardiac arrest, and stroke. We also compared in-hospital mortality with and without cardiovascular complications.

RESULTS

Among 15,054 thrombotic thrombocytopenic purpura hospitalizations (mean age 46.4 years, 69% in the 18- to 54-age group, 66.2% women, and 42.9% white), a cardiovascular complication was observed in 3802 (25.3%) hospitalizations. The following cardiovascular complications were identified: stroke (10.4%), heart failure (8.3%), acute coronary syndrome (6.4%), atrial tachyarrhythmia (5.9%), ventricular tachyarrhythmia (2.0%), cardiogenic shock (0.5%), takotsubo cardiomyopathy (0.1%), atrioventricular block (0.2%), myocarditis or pericarditis (0.3), and cardiac arrest (1.9%). Rates of several cardiovascular complications were significantly higher in patients 55 years or older compared to a younger age group, whereas males had higher rates of acute coronary syndrome and tachyarrhythmias compared to females. Overall, the cardiovascular complication rate was stable during the study period. The presence of a major cardiovascular complication was associated with a significantly higher in-hospital mortality (19.7%) as compared with no major cardiovascular complication (4.1%) (adjusted odds ratio 2.09, 95% confidence interval 1.41-3.09, P <0.001). Results were generally consistent in age and sex subgroups.

CONCLUSION

Cardiovascular complications were frequently observed at a rate of 1 in 4 in patients hospitalized for thrombotic thrombocytopenic purpura and were associated with substantially higher in-hospital mortality. These findings underscore the need to promptly identify and treat these complications to improve outcomes.

Burden of illness among Medicare and non-Medicare US populations with acquired thrombotic thrombocytopenic purpura

BACKGROUND

Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare hematologic disorder that can lead to serious life-threatening medical complications.

OBJECTIVE

The aim of this study was to describe aTTP-related hospital resource utilization, cost, complications, and overall survival among US Medicare and non-Medicare populations following aTTP episodes prior to the US approval of caplacizumab.

METHODS

This retrospective study utilized administrative claims data for Medicare Fee-for-Service (FFS) beneficiaries (100% sample) and a sample of commercial, managed Medicaid [MM], Medicare Advantage [MA] plan members from the Inovalon MORE² Registry. aTTP patients ages 18+ were identified between 2010 and 2018 using a published validated algorithm: ≥1 hospitalization for thrombotic microangiopathy + therapeutic plasma exchange (TPE). 2,279 patients were identified; 65.2% were enrolled in Medicare FFS, 13.6% in commercial, 15.7% in MM, and 5.4% in MA. Mean hospitalization days for aTTP index episode ranged between 12 and 17 days; ∼60% of patients required intensive care. Mean payments for index hospitalization varied by payer [Medicare FFS: $29,024; MA: $12,860; commercial: $9,996 and MM: $10,470]. Among FFS patients, 15.7% died during initial hospitalization and 21.0% died within first 30 days of the event. During follow-up, 11.6-19.6% experienced aTTP-related exacerbation. Incidence rate of relapse and complications per 100 person-years was 5.6 [Medicare FFS: 3.6; MA: 8.7; commercial: 10.4 and MM: 14.7] and 16.7 [FFS: 15.5; MA: 20.5; commercial: 21.7 and MM: 19.1], respectively. Among Medicare patients with and without aTTP, mortality risk was 2.9 (95 % CI: 2.4-3.4) times higher for aTTP vs. non-aTTP patients.

CONCLUSION

This is the first real-world study evaluating burden of illness among aTTP patients in the US across payer types. Despite being treated with TPE, patients with aTTP have lower survival rates in comparison to a matched cohort without aTTP. These findings highlight the need for more effective and novel therapies to reduce disease burden for this population.Key pointsIn US Medicare and managed care populations with aTTP between 2010 and 2018, aTTP can lead to significant utilization of ICU services due to clinical complications, and/or relapse following hospital discharge.Despite treatment with therapeutic plasma exchange, acute mortality remains high (15.7%) indicating the need for more effective and novel treatments.

Cost analysis of the impact of caplacizumab in the treatment of acquired thrombotic thrombocytopenic purpura from a US hospital perspective

AIM

This study aimed to model the financial impact of caplacizumab with therapeutic plasma exchange (TPE) + immunosuppression for patients experiencing an acute acquired thrombotic thrombocytopenic purpura (aTTP) episode versus TPE + immunosuppression, from a US hospital's perspective.

METHODS AND MATERIALS

We developed an economic model to estimate the impact of caplacizumab on a US hospital's budget. Cost offsets from caplacizumab utilization targeted inpatient general ward days, intensive care unit (ICU) days, and TPE utilization. Costs and event probabilities were estimated from primary data analyses of the phase 3 HERCULES trial and peer-reviewed literature or other public sources. Plan reimbursement was obtained from 2019 Medicare Fee Schedules and adjusted to represent reimbursement from different US payers. Cost of ICU and general ward utilization were estimated from Medicare Provider Analysis and Review data analyses capturing hospital discharges.

RESULTS

The model results indicate that caplacizumab leads to hospitalization cost savings of over $8,000 ($23,148 versus $14,904) along with TPE cost savings of over $14,000 ($37,150 versus $23,033) per patient. When the cost of caplacizumab and plan reimbursement are incorporated into the results, the per-patient cost of TPE + immunosuppression is $23,120 versus $70,068 for caplacizumab with TPE + immunosuppression, an incremental cost of $46,948. The model was robust to several scenario analyses; however, when limited to Medicare fee-for-service (FFS), the incremental cost of caplacizumab per patient was reduced to $4,852 due to add-on payments.

CONCLUSIONS

Caplacizumab with TPE + immunosuppression is associated with an increase in costs; however, the increase is nominal among payers who provide an add-on payment consistent with that of Medicare FFS.

Good practice statements (GPS) for the clinical care of patients with thrombotic thrombocytopenic purpura

BACKGROUND

Despite advances in treatment options for thrombotic thrombocytopenic purpura (TTP), there are still limited high quality data to inform clinicians regarding its management.

METHODS

In June 2018, the ISTH formed a multidisciplinary guideline panel to issue recommendations about treatment of TTP. The panel discussed 12 treatment questions related to both immune-mediated TTP (iTTP) and hereditary/congenital TTP (cTTP). The panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, including evidence-to-decision frameworks, to appraise evidence and formulate recommendations.

RESULTS

The panel agreed on eleven recommendations based on evidence ranging from very low to moderate certainty. For first episode and relapses of acute iTTP, the panel made a strong recommendation for the addition of corticosteroids to therapeutic plasma exchange (TPE), and a conditional recommendation for addition of rituximab and caplacizumab. For asymptomatic iTTP with low ADAMTS13, the panel made a conditional recommendation for rituximab outside of pregnancy, and for prophylactic TPE during pregnancy. For asymptomatic cTTP, the panel made a strong recommendation for prophylactic plasma infusion during pregnancy, but a conditional recommendation for plasma infusion or a wait and watch approach outside of pregnancy.

CONCLUSIONS

The panel's recommendations are based on all the available evidence for the treatment effects of various approaches including suppressing inflammation, blocking platelet clumping, replacing the missing and/or inhibited ADAMTS13, and suppressing ADAMTS13 antibody production. There was insufficient evidence for further comparison of different treatment approaches, for which future high-quality studies in iTTP (e.g., rituximab, corticosteroids, recombinant ADAMTS13, and caplacizumab) and in cTTP (eg, recombinant ADAMTS13) are needed.

Development and validation of a prediction model (AHC) for early identification of refractory thrombotic thrombocytopenic purpura using nationally representative data

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening haematological emergency. Although therapeutic plasma exchange together with corticosteroids achieve successful outcomes, a considerable number of patients remain refractory to this treatment and require early initiation of intensive therapy. However, a method for the early identification of refractory iTTP is not available. To develop and validate a model for predicting the probability of refractory iTTP, a cohort of 265 consecutive iTTP patients from 17 large medical centres was retrospectively identified. The derivation cohort included 94 patients from 11 medical centres. For the validation cohort, we included 40 patients from the other six medical centres using geographical validation. An easy-to-use risk score system was generated, and its performance was assessed using internal and external validation cohorts. In the multivariable logistic analysis of the derivation cohort, three candidate predictors were entered into the final prediction model: age, haemoglobin and creatinine. The prediction model had an area under the curve of 0.886 (95% CI: 0.679-0.974) in the internal validation cohort and 0.862 (95% CI: 0.625-0.999) in the external validation cohort. The calibration plots showed a high agreement between the predicted and observed outcomes. In conclusion, we developed and validated a highly accurate prediction model for the early identification of refractory iTTP. It has the potential to guide tailored therapy and is a step towards more personalized medicine.

Predictors of In-Hospital Mortality in Thrombotic Thrombocytopenic Purpura in Children in the United States: A Population Analysis

BACKGROUND

Despite proven efficacy and increased availability of therapeutic plasma exchange, thrombotic thrombocytopenic purpura (TTP) is associated with significant morbidity and mortality.

STUDY DESIGN AND METHODS

This study utilized the Kids' Inpatient Database and National Inpatient Sample (2003 to 2016) to study predictors of in-hospital mortality in hospitalized TTP patients. Adjusted odds ratios of death with various putative risk factors were calculated using multiple regression analysis.

RESULTS

Among 1568 hospitalizations with TTP as primary admission diagnosis who underwent therapeutic plasma exchange, 69 deaths were identified (all-cause mortality, 0.04%; median time-to-death, 6 wk). Overall, hospitalizations rates were fairly similar across the study period. The overall incidence of TTP related hospitalizations is 1.51 per 100,000 hospitalizations. A total of 69 deaths were reported with an all-cause in-hospital mortality rate of 0.04% (69/1568). The median time-to-death was 6 weeks. The majority of deaths occurred in age 16 to 20 years (58%), females (56.5%), and African American (42.9%) as shown in Table 2. Mean age for nonsurvivors was 14 years and the mean age of 15 years for survivors (P=0.01). Younger age, male sex, African-American ethnicity, malignancy, sepsis, acute kidney injury, platelet transfusion was significantly associated with mortality in patients with TTP.

CONCLUSIONS

Early and targeted therapy for high risk individuals should be used to guide management of TTP patients for improved survival outcomes.

Immune thrombotic thrombocytopenic purpura in older patients: prognosis and long-term survival

Older age is associated with increased mortality in immune thrombotic thrombocytopenic purpura (iTTP). Yet, data are scarce regarding iTTP occurring among older patients. To assess clinical features and long-term impact of iTTP on mortality in older patients (>60 years old), characteristics and prognoses of adult iTTP patients enrolled in the French Reference Center for Thrombotic Microangiopathies registry between 2000 and 2016 were described according to age (<60 years old or ≥60 years old). Long-term mortality of iTTP older survivors was compared with that of non-iTTP geriatric subjects. Comparing, respectively, older iTTP patients (N = 71) with younger patients (N = 340), time from hospital admission to diagnosis was longer (P < .0001); at diagnosis, delirium (P = .034), behavior impairment (P = .045), renal involvement (P < .0001), and elevated troponin level (P = .025) were more important whereas cytopenias were less profound (platelet count, 22 × 103/mm3 [9-57] vs 13 × 103/mm3 [9-21], respectively [P = .002]; hemoglobin level, 9 g/dL [8-11] vs 8 g/dL [7-10], respectively [P = .0007]). Short- and mid-term mortalities were higher (P < .0001) and increased for every 10 years of age range. Age ≥60 years, cardiac involvement, increased plasma creatinine level, and total plasma exchange volume were independently associated with 1-month mortality. Compared with a non-iTTP geriatric population, older survivors showed an increased long-term mortality (hazard ratio = 3.44; P < .001). In conclusion, older iTTP patients have atypical neurological presentation delaying the diagnosis. Age negatively impacts short-term but also long-term mortality.

Solvent detergent treated pooled plasma and reduction of allergic transfusion reactions

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) patients have increased risk for allergic transfusion reactions (ATR) due to the number of plasma products they require. This study evaluated the efficacy of solvent detergent treated plasma (S/D treated plasma) to reduce ATRs.

STUDY DESIGN AND METHODS

All TTP patients who presented from April 2014 to February 2015 and experienced a moderate-severe ATR to untreated plasma with TPE were switched to S/D treated plasma (Octaplas) for their remaining procedures and included in the study. Patient records were retrospectively reviewed.

RESULTS

The overall ATR rate per procedure decreased from 35.0% (95% CI = 15.4%-59.2%) with untreated plasma to 1.4% ([1/73] 95% CI = 0.0%-7.4%) with S/D treated plasma. The moderate-severe ATR rate decreased from 20.0% ([4/20] 95% CI = 5.7%-43.7%) with untreated plasma to 0.0% ([0/73] 95% CI = 0.0%-4.9%) with S/D treated plasma. The overall ATR rate per plasma unit decreased from 2.6% (95%CI = 1.0%-5.1%) with untreated plasma to 0.1% (95% CI = 0.0%-0.4%) with S/D treated plasma. No patients experienced VTE while receiving untreated plasma. Four patients experienced VTE events while receiving S/D treated plasma. All patients who experienced a VTE had additional risk factors for VTE.

CONCLUSION

S/D plasma has promise as an effective product to reduce the risk of ATRs in TTP patients. Given the high risk of ATR in TTP patients, consideration of S/D plasma instead of untreated plasma for TPE in these patients may be warranted, especially for patients with a history of moderate to severe ATR. More extensive studies are needed to confirm these findings.

Incidence of acquired thrombotic thrombocytopenic purpura in Germany: a hospital level study

Background

Acquired thrombotic thrombocytopenic Purpura (aTTP) is a life-threatening ultra-orphan disease with a reported annual incidence between 1.5 and 6.0 cases per million in Europe and mainly affecting otherwise young and healthy adults aged 40 years on average. The goal of this study was to assess the incidence of aTTP in Germany.

Methods

A systematic review was performed to determine the published evidence on the aTTP epidemiology in Germany. To obtain additional evidence on the proportion of aTTP cases within the national Thrombotic Microangiopathy (TMA) population a hospital-level study was performed, using a retrospective data collection approach. Diagnosis of aTTP was confirmed if ADAMTS13 level were < 10% and/or the medical records explicitly mentioned aTTP diagnosis. The aggregated hospital data were then projected to the national level using logistic regression techniques.

Results

The systematic literature search did not provide incidence estimates of aTTP in Germany. Eight centers (≈27% of the top 30 TMA hospitals) delivered data according to a predefined data collection form. On average (year 2014–2016) a total number of 172 aTTP episodes per year was projected (95% confidence interval [95%CI]: 132–212). The majority were newly diagnosed aTTP cases (n = 121; 95%CI: 105–129), and 51 were recurrent aTTP cases (95%CI: 27–84). The average annual projected incidence (year 2014–2016) of aTTP episodes was 2.10 per million inhabitants in Germany (95%CI: 1.60–2.58).

Conclusions

The determined annual incidence of newly diagnosed aTTP cases and the overall annual incidence of aTTP episodes in Germany confirm the ultra-orphan character of aTTP. An external validation against international registries (France, UK and USA) shows that our findings are quite comparable with those international incidence rates.

Expert statement on the ICU management of patients with thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is fatal in 90% of patients if left untreated and must be diagnosed early to optimize patient outcomes. However, the very low incidence of TTP is an obstacle to the development of evidence-based clinical practice recommendations, and the very wide variability in survival rates across centers may be partly ascribable to differences in management strategies due to insufficient guidance. We therefore developed an expert statement to provide trustworthy guidance about the management of critically ill patients with TTP. As strong evidence was difficult to find in the literature, consensus building among experts could not be reported for most of the items. This expert statement is timely given the recent advances in the treatment of TTP, such as the use of rituximab and of the recently licensed drug caplacizumab, whose benefits will be maximized if the other components of the management strategy follow a standardized pattern. Finally, unanswered questions are identified as topics of future research on TTP.

Clinical Efficacy and Safety Profile of Caplacizumab for Acquired Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) is usually defined as microangiopathy characterized by low platelet count and low red blood cell count, i.e., hemolytic anemia. It can either be acquired or immune-mediated. TTP requires quick diagnostic identification and emergent management. According to the evidence-based guidelines, the recommended therapy is plasma exchange and immunosuppression. Caplacizumab is used alongside the standard recommended therapy. Caplacizumab is a monoclonal antibody (Mab) that binds to von Willebrand factor (VWF). This prevents A1 VWF to bind platelet glycoprotein 1b receptor. The recommended dosage for this drug is 10mg. At the start, 10mg intravenous (IV) dose is given before plasma exchange, followed by daily 10mg subcutaneous (SC) dose after plasma exchange. Moreover, the SC dose is continued even after the daily plasma exchange is stopped. This review aims to consolidate findings related to the efficacy of this recently approved drug.

Contemporary Diagnosis and Management of Patients With Myocardial Infarction in the Absence of Obstructive Coronary Artery Disease: A Scientific Statement From the American Heart Association

Myocardial infarction in the absence of obstructive coronary artery disease is found in ≈5% to 6% of all patients with acute infarction who are referred for coronary angiography. There are a variety of causes that can result in this clinical condition. As such, it is important that patients are appropriately diagnosed and an evaluation to uncover the correct cause is performed so that, when possible, specific therapies to treat the underlying cause can be prescribed. This statement provides a formal and updated definition for the broadly labelled term MINOCA (incorporating the definition of acute myocardial infarction from the newly released “Fourth Universal Definition of Myocardial Infarction”) and provides a clinically useful framework and algorithms for the diagnostic evaluation and management of patients with myocardial infarction in the absence of obstructive coronary artery disease.

Presenting ADAMTS13 antibody and antigen levels predict prognosis in immune-mediated thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder caused by antibodies against ADAMTS13. From the United Kingdom TTP registry, we undertook a prospective study investigating the impact of the presenting anti-ADAMTS13 IgG antibody and ADAMTS13 antigen on mortality. A total of 312 episodes involving 292 patients over 87 months were included; 68% were female, median age 46 (range, 11-88 years), and median presenting ADAMTS13 of <5% (range, <5%-18%). The mortality rate was 10.3% (n = 32); 68% of patients had a raised troponin at presentation conferring a sixfold increase in mortality compared with those with normal troponin levels (12.1% vs 2.0%, P = .04). Twenty-four percent had a reduced Glasgow Coma Score (GCS) at presentation with a ninefold increase in mortality (20% vs 2.2% for normal GCS at presentation, P < .0001). Mortality increased with higher anti-ADAMTS13 antibody levels and lower ADAMTS13 antigen levels. Those with antibody levels in the upper quartile (antibody >77%) had a mortality of 16.9% compared with 5.0% for the lowest quartile (antibody <20%) (P = .004). Those with an antigen level in the lowest quartile (antigen <1.5%) had a mortality of 18% compared with 3.8% for the highest quartile (antigen >11%) (P = .005). The synergistic effect of anti-ADAMTS13 IgG antibody in the upper quartile and ADAMTS13 antigen in the lowest quartile had the highest mortality of 27.3%. We conclude that both anti-ADAMTS13 IgG antibody and ADAMTS13 antigen levels correlate with outcome in TTP with increased cardiac and neurological involvement and increased mortality.

Caplacizumab reduces the frequency of major thromboembolic events, exacerbations and death in patients with acquired thrombotic thrombocytopenic purpura

Essentials Acquired thrombotic thrombocytopenic purpura (aTTP) is linked with significant morbidity/mortality. Caplacizumab's effect on major thromboembolic (TE) events, exacerbations and death was studied. Fewer caplacizumab-treated patients had a major TE event, an exacerbation, or died versus placebo. Caplacizumab has the potential to reduce the acute morbidity and mortality associated with aTTP.

SUMMARY

Background Acquired thrombotic thrombocytopenic purpura (aTTP) is a life-threatening autoimmune thrombotic microangiopathy. In spite of treatment with plasma exchange and immunosuppression, patients remain at risk for thrombotic complications, exacerbations, and death. In the phase II TITAN study, treatment with caplacizumab, an anti-von Willebrand factor Nanobody® was shown to reduce the time to confirmed platelet count normalization and exacerbations during treatment. Objective The clinical benefit of caplacizumab was further investigated in a post hoc analysis of the incidence of major thromboembolic events and exacerbations during the study drug treatment period and thrombotic thrombocytopenic purpura-related death during the study. Methods The Standardized Medical Dictionary for Regulatory Activities (MedDRA) Query (SMQ) for 'embolic and thrombotic events' was run to investigate the occurrence of major thromboembolic events and exacerbations in the safety population of the TITAN study, which consisted of 72 patients, of whom 35 received caplacizumab and 37 received placebo. Results Four events (one pulmonary embolism and three aTTP exacerbations) were reported in four patients in the caplacizumab group, and 20 such events were reported in 14 patients in the placebo group (two acute myocardial infarctions, one ischemic stroke, one hemorrhagic stroke, one pulmonary embolism, one deep vein thrombosis, one venous thrombosis, and 13 aTTP exacerbations). Two of the placebo-treated patients died from aTTP during the study. Conclusion In total, 11.4% of caplacizumab-treated patients and 43.2% of placebo-treated patients experienced one or more major thromboembolic events, experienced an exacerbation, or died. This analysis shows the potential for caplacizumab to reduce the risk of major thromboembolic morbidities and mortality associated with aTTP.