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.

Maternal and fetal outcomes of pregnancy occurring after a diagnosis of immune-mediated thrombotic thrombocytopenic purpura

Pregnancy is a well-established trigger for a first episode or relapse of immune thrombotic thrombocytopenic purpura (iTTP). Other outcomes of subsequent pregnancy after a diagnosis of iTTP are less well described. We conducted this retrospective cohort study to evaluate maternal and fetal outcomes of pregnancy in women with prior iTTP from the Johns Hopkins Thrombotic Microangiopathy Cohort. Of 168 women in the cohort, 102 were of reproductive age at diagnosis. Fourteen pregnancies (in 9 women) that occurred after the initial iTTP episode were included in the analysis. iTTP relapse occurred in 9 (64%) pregnancies. Out of the 9 instances of relapse, 5 relapses occurred in 2 women. Seven pregnancies (50%) ended in fetal death or miscarriage in the setting of iTTP relapse and three were electively terminated due to fear of relapse. Four pregnancies (50% of the 8 that progressed beyond 20 weeks) were complicated by preeclampsia or HELLP syndrome, which is over ten-fold higher than that of the general population. No maternal deaths occurred. Only 4 pregnancies resulted in live births, of which, 2 were pre-term. Pregnancy in women with prior iTTP is associated with a substantial risk of iTTP relapse and fetal loss. Preeclampsia and HELLP syndrome is also more common than that in the general population. ADAMTS13 monitoring and preemptive therapy may improve pregnancy outcomes, which needs to be evaluated prospectively.

Race, rituximab, and relapse in TTP

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is characterized by recurring episodes of thrombotic microangiopathy, causing ischemic organ impairment. Black patients are overrepresented in iTTP cohorts in the United States, but racial disparities in iTTP outcome and response to therapy have not been studied. Using the United States Thrombotic Microangiopathies Consortium iTTP Registry, we evaluated the impact of race on mortality and relapse-free survival (RFS) in confirmed iTTP in the United States from 1995 to 2020. We separately examined the impact of rituximab therapy and presentation with newly diagnosed (de novo) or relapsed iTTP on RFS by race. A total of 645 participants with 1308 iTTP episodes were available for analysis. Acute iTTP mortality did not differ by race. When all episodes of iTTP were included, Black race was associated with shorter RFS (hazard ratio [HR], 1.60; 95% CI, 1.16-2.21); the addition of rituximab to corticosteroids improved RFS in White (HR, 0.37; 95% CI, 0.18-0.73) but not Black patients (HR, 0.96; 95% CI, 0.71-1.31). In de novo iTTP, rituximab delayed relapse, but Black patients had shorter RFS than White patients, regardless of treatment. In relapsed iTTP, rituximab significantly improved RFS in White but not Black patients. Race affects overall relapse risk and response to rituximab in iTTP. Black patients may require closer monitoring, earlier retreatment, and alternative immunosuppression after rituximab treatment. How race, racism, and social determinants of health contribute to the disparity in relapse risk in iTTP deserves further study.

Major adverse cardiovascular events in survivors of immune-mediated thrombotic thrombocytopenic purpura

Cardiovascular disease is a leading cause of death in survivors of immune-mediated thrombotic thrombocytopenic purpura (iTTP), but the epidemiology of major adverse cardiovascular events (MACE) in iTTP survivors is unknown. We evaluated the prevalence and risk factors for MACE, defined as the composite of non-fatal or fatal myocardial infarction (MI), stroke, and cardiac revascularization, during clinical remission in two large iTTP cohorts (Johns Hopkins University and Ohio State University). Of 181 patients followed for ≥ 3 months after recovery from acute iTTP, 28.6% had a MACE event over a median follow up of 7.6 years. Stroke was the most common type of MACE (18.2%), followed by non-fatal MI (6.6%), cardiac revascularization (4.9%) and fatal MI (0.6%). Compared to the general United States population, iTTP survivors were younger at first stroke in remission (males [56.5 years vs. 68.6 years, p = 0.031], females [49.7 years vs. 72.9 years, p <  0.001]) or MI in remission (males [56.5 years vs. 65.6 years, p <  0.001] and females [53.1 years vs. 72.0 years, p < 0.001]). Age (HR 1.03 [95% CI 1.002-1.054]), race (Black/Other vs. White) (HR 2.32 [95% CI 1.12-4.82]), and diabetes mellitus (HR 2.37 [95% CI 1.09-0.03]) were associated with MACE in a Cox regression model also adjusted for sex, hypertension, obesity, hyperlipidemia, chronic kidney disease, atrial fibrillation, autoimmune disease, and relapsing iTTP. Remission ADAMTS13 activity was not significantly associated with MACE. In conclusion, iTTP survivors experience high rates of MACE and may benefit from aggressively screening for and managing cardiovascular risk factors.

Therapeutic plasma exchange taper does not decrease exacerbations in immune thrombotic thrombocytopenic purpura patients

BACKGROUND

Despite rapid and intensive treatments with therapeutic plasma exchange (TPE) and immunosuppression, immune thrombotic thrombocytopenic purpura (TTP) patients are at risk of disease exacerbation, i.e., early recurrence of TTP within 30 days of achieving treatment response. TPE taper, a practice of performing additional TPE procedures after achieving treatment response, is commonly performed for decreasing exacerbations, although no evidence supports this practice.

STUDY DESIGN AND METHODS

In this prospective observational investigation over four years, our center switched its standard of care for treating all TTP patients from not performing TPE taper after achieving treatment response (i.e., no-taper cohort) to performance of TPE taper (i.e., yes-taper cohort) to characterize impacts on exacerbations. Continuous and categorical data were analyzed by Mann-Whitney, Fisher's exact, and log-rank tests; significance was defined as p < 0.05.

RESULTS

The two cohorts were well matched and had no significant differences in demographics, presentation laboratory values, or TTP history (p > 0.05 for all). The yes-taper cohort of 26 patients with 29 consecutive episodes did not have a significantly different exacerbation rate from the no-taper cohort of 24 patients with 27 consecutive episodes (exacerbation rates of 37.9% vs. 33.3%, respectively; p = 0.78); however, treatment-related complications directly attributed to the TPE procedures, blood products, or central venous catheters were significantly greater in the yes-taper cohort (nine vs. one events, respectively; p = 0.01).

CONCLUSION

Since TPE taper did not reduce exacerbations in our TTP patients, we no longer advocate for TPE taper and have reverted to our original standard of care.

The Impact of an Undergraduate Biology Class on Donor Recruitment at a Hospital-Based Blood Donor Center

OBJECTIVES

A biology class, BIOL 294H, taught undergraduates about platelet donation while partnering with the University of North Carolina's (UNC's) hospital-based Blood Donation Center to recruit apheresis platelet donors. We identified our platelet donors' demographics and learned how BIOL 294H affected recruitment.

METHODS

Every platelet donor presenting to the UNC Blood Donation Center from February 7, 2017, to March 10, 2017, was asked to complete an electronic 10-question survey.

RESULTS

A total of 159 unique donors completed the survey; 64% were female and 75% were between ages 18 and 25 years. Overall, 70% were UNC undergraduate students. Over half (56%) reported first learning about platelet donation through word of mouth, and 22% cited specific efforts associated with BIOL 294H.

CONCLUSIONS

Recruitment of undergraduate platelet donors primarily included BIOL 294H peer interactions and deliverables from the class, such as social media updates and events on campus. The sustained recruiting efforts of our students over many years contributed to recruitment of a majority of our platelet donors.

The top 10 things to know about transfusion medicine before intern year: an evidence-based course for graduating medical students

Background

Transfusion medicine (TM) knowledge varies widely among physician trainees. In addition, there have been few instances in which curricular changes have been meaningfully assessed for TM education in medical school.

Methods

We created and presented a novel lecture to improve TM knowledge for graduating medical students using eight objectives designed to reinforce critical information about blood management. Each objective was coded according to unique color schemes, fonts, and graphics to create visual associations while quickly and clearly presenting complex concepts. The validated BEST Collaborative exam was used to measure changes in student TM knowledge, while a survey was conducted to gauge changes in confidence for each objective. Students were asked to submit anonymous feedback about their experiences.

Results

The mean student post-course exam score was 50.0%, while the pre-course baseline score was 27.5% (P<0.0001). Mean confidence levels increased significantly for all objectives. Student feedback was universally positive.

Conclusion

This study improved knowledge and confidence for graduating medical students by utilizing engaging and visually stimulating presentations to display high-impact TM material. However, further efforts are needed to optimize learning.

Coated platelets and severe haemophilia A bleeding phenotype: Is there a connection?

INTRODUCTION

Coated platelets are a subpopulation of platelets that possess highly prothrombotic properties. Previous observational data suggest that bleeding phenotype in severe haemophilia A is associated with coated platelet levels. Haemophilia A patients with higher coated platelet levels may have a mild bleeding phenotype; those with lower levels may have a more severe bleeding phenotype.

AIM

The aim of the study was to test the hypothesis that coated platelet levels are correlated with clinical bleeding phenotype.

METHODS

This cross-sectional, observational study enrolled 20 severe haemophilia A patients, including 15 with severe and five with a mild bleeding phenotype, and a control group of 12 healthy volunteers. The haemophilia bleeding phenotype was determined by the patient's medical history and haemophilia treatment centre records. Blood was obtained from each patient by venipuncture and platelets were analysed by flow cytometry.

RESULTS

Patients categorized as having a severe bleeding phenotype experienced a median eight bleeds per year compared to one bleed annually in the mild bleeding phenotype group. Both groups had similar total platelet counts and fibrinogen levels. There was no difference in coated platelet percentage between severe and mild bleeding phenotype (17 and 16% respectively), however, both groups had significantly lower % coated platelets compared to controls (44%, P < 0.0001).

CONCLUSION

Coated platelet levels were not associated with bleeding phenotype in this study; however, these data may suggest coated platelet levels are lower in haemophilia patients relative to healthy volunteers.

Passive reporting greatly underestimates the rate of transfusion-associated circulatory overload after platelet transfusion

BACKGROUND

Transfusion-associated circulatory overload (TACO) is the second leading cause of reported transfusion-related fatalities in the United States. While its occurrence has been previously investigated after red cell and plasma transfusion, no data are available regarding its association with platelet transfusion. Our goal was to determine the rate of platelet-associated TACO at our university medical centre.

STUDY DESIGN AND METHODS

This study had retrospective and prospective analyses. The 13-year retrospective analysis served to determine the historical rate of platelet-associated TACO by passive reporting. The 30-day prospective analysis included active surveillance of all non-emergently issued and non-operative platelet recipients ≥16 years old with no transfusions in the previous 6 h determined by analysis of blood bank product issue records. Data collected included demographics, vital signs pre- and posttransfusion, fluid balances, supplemental oxygen use, reports of dyspnoea, and infusion rates. For the prospective analysis, all variables were collected within 24 h of transfusion from the medical record and, when necessary, interviews with care providers and/or patients.

RESULTS

In the retrospective analysis, 366 reactions were reported, of which 6 (1·6%) were TACO. The historical rate of TACO was 1:5997 transfused platelet units. During the prospective analysis, 225 eligible patients received a total of 334 units of platelets. The average platelet transfusion volume was 261 ± 26 ml, and the average infusion rate was 391 ± 198 ml/h. Two unreported TACO reactions were discovered and characterized by new-onset hypertension, crackles on lung auscultation, dyspnoea, hypoxia and supplemental oxygen requirements which resolved completely with diuresis. The rate of TACO during this prospective analysis was 1:167 transfused platelet units.

CONCLUSION

Platelet-associated TACO is greatly underestimated by passive reporting in the adult patient population.

Two cases of asymptomatic massive fetomaternal hemorrhage

Evaluation of fetomaternal hemorrhage (FMH) in the immediate postpartum period is critical for the timely administration of Rh immunoglobulin (RhIG) prophylaxis to minimize the risk of alloimmunization in D-negative mothers of D-positive newborns. We report a series of two clinically-unsuspected cases of massive FMHs identified at our university medical center. Retrospective records of two cases of massive FMH were investigated using the electronic medical record. After positive fetal bleed screens, flow cytometric analysis for hemoglobin F was performed to quantify the volume of the hemorrhages in both cases. Flow cytometric enumeration with anti-D was also performed in one case. The two patients had 209.5 and 75 mL of fetal blood in circulation, resulting in 8 and 4 doses of RhIG administered, respectively. For the former patient, flow cytometric analysis with anti-D ruled out hereditary persistence of fetal hemoglobin and supported the fetal origin of the red cells. Due to the clinically-silent nature of both hemorrhages, further evaluation of the newborns' blood was not performed. These cases highlight the importance of rapidly obtaining accurate measurements of fetal blood loss via flow cytometric analysis in cases of FMH, particularly in clinically-unsuspected cases, to ensure timely administration of adequate immunoprophylaxis to D-negative mothers.

Pathology consultation on electronic crossmatch

OBJECTIVES

The full crossmatch is traditionally the final step in compatibility testing, acting as a serologic double check for ABO compatibility and unexpected RBC antibodies. In this review, we discuss the development of electronic crossmatch (EXM), an approach for determining when EXM can be used, and its strengths and weaknesses.

METHODS

Because EXM relies on highly sensitive screening assays, antibodies are frequently encountered whose clinical significance must be investigated and interpreted. Our approach is to obtain further history, perform enhanced tube testing, and consider tests of immune reactivity or RBC survival.

RESULTS

For those without clinically significant antibodies, we found two alternatives: immediate-spin crossmatch (IS XM) and EXM. IS XM is prone to error related to serologic interference, whereas EXM depends on the accuracy of the sample label, accurate data entry, and informatics to avoid errors.

CONCLUSION

EXM is an alternative to the serologic test in patients who have no clinically significant antibodies.

[Modernization of a photoelectric transducer for liquid chromatography]

Photoelectric sensor for fraction automatic collector of liquid chromatograph which eliminates violation of the movable collector mechanism working rhythm, prevents liquid samples losses, excludes changes in fraction structures of the samples and pollution is described. The mentioned above benefits were gained due to replenishment of the unit with the industrial photoelectric sensor, which consists of the funnel with the through central opening, eccentrically located platform and a shaft with the longitudinal channel for the liquid to pass in the photoresistor plane and with the diametrically located window for the light bunch, coming from the lamp to the photoresistor, which signal is transferred to the movable mechanism.