Casanegra, Ana I.

ABSTRACT Background Platelet factor 4‐polyanion enzyme‐linked immunosorbent assays (ELISAs) are considered highly sensitive for diagnosing heparin‐induced thrombocytopenia (HIT), such that current practice guidelines recommend use of ELISA‐negative results to exclude HIT. Once HIT is ruled out, alternative, non‐heparin‐based anticoagulant treatments are ceased, and heparin reintroduction frequently occurs. Methods Antigen‐based and PF4‐dependent functional testing were used to study PF4/polyvinylsulfonate ELISA‐negative platelet‐activating antibodies in HIT‐suspected patients. Results Three patients with clinical presentations consistent with HIT tested negative in an ELISA using PF4‐polyvinylsulfonate (PF4/PVS), an antigenic target very commonly used for HIT antibody screening. All three patients demonstrated PF4‐dependent platelet activation in functional testing that was sensitive to blockade of platelet FcγRIIa receptors and inhibited by high concentrations of heparin, consistent with pathogenic HIT antibodies. Functional testing‐based screening of 500 ELISA‐negative patients identified three additional patients whose sera activated platelets in a PF4‐ and FcγRIIa‐dependent manner and had clinical histories consistent with HIT. Five of the six ELISA‐negative HIT patients were re‐exposed to heparin, which precipitated a decrease in platelet counts in all re‐exposed patients, and one patient developed a new thrombus. Conclusions Recognition of ELISA‐negative HIT is critical to avoid harm due to the cessation of alternative anticoagulation therapy and re‐exposure of these patients to heparin.

Background: Chronic venous insufficiency (CVI) can be evaluated using Duplex ultrasonography (US) and air plethysmography (PG), yet comparative performance remains unclear. Methods: We retrospectively identified patients who underwent venous insufficiency US and PG within a 90-day interval from March 1, 2015 through July 31, 2024. CVI severity was classified by the clinical (C) component of the Clinical, Etiologic, Anatomic, and Pathophysiologic (CEAP) classification system and categorized as mild (C0–2), moderate (C3), or severe (C4–6). PG and insufficiency US findings were compared across categories and machine learning models were trained to predict severe CVI. Results: We analyzed 1478 limbs from 839 patients who were predominantly women (62%) with a mean age of 61 years (± 14 years). Severe CVI was present in 32.3% of limbs. US detected venous incompetence in 67.4% of limbs overall and in 75.3% of severe CVI limbs. Abnormal PG findings occurred in 72.9% of limbs overall and in 88.5% of severe CVI limbs. PG parameters in machine learning models outperformed US parameters in predicting severe CVI (area under the receiver operating characteristic curve [AUROC] 0.82 vs 0.65). The top PG model (multilayer perceptron [MLP]) achieved an AUROC of 0.82, versus the best US model (gradient boosting) with an AUROC of 0.65. Limiting PG data to incompetence and obstruction parameters modestly reduced performance but remained higher than US (logistic regression AUROC 0.72). Conclusion: Our findings indicate that PG assessment in CVI offers superior performance compared to US. Overall, these results validate the quantitative whole-limb hemodynamic approach using PG, which provides a more complete understanding of the pathology behind CVI.

Abstract Optimal management of anticoagulation for patients with aortic mechanical heart valves (MHVs) receiving vitamin K antagonists (VKAs) undergoing gastrointestinal endoscopic procedures is clinically challenging. Risk of bleeding from an unanticipated polypectomy or biopsy further complicates this issue. Current guidelines on use of bridging with low-molecular-weight heparin (LMWH) for these procedures are based on low-quality evidence. We conducted a subanalysis of a retrospective, multicenter observational study of adult patients with aortic MHVs receiving VKAs who underwent elective gastrointestinal endoscopies (colonoscopy or upper endoscopy). We included patients who underwent the procedure between July 1, 2020, and July 1, 2023, at five centers in Canada and the United States Patients with procedures performed on separate days within a 30-day period were excluded. Efficacy and safety outcomes included thromboembolic events, major bleeding (MB), and clinically relevant non-major bleeding (CRNMB) in the 30 days post procedure. A total of 192 endoscopic procedures were analyzed. Median (interquartile range [IQR]) patient age was 66 years (58.2–72.8) and 22% were female. Warfarin was interrupted for 185 procedures (96%). Among these, 119 (64%) received LMWH bridging: 33 (17%) pre-procedure only, 10 (5%) post-procedure only, and 76 (40%) both pre- and post-procedure. Post-procedure LMWH was initiated a median (IQR) of 1 day (1–1) and discontinued 5 days post-procedure (3–8). MB occurred in two patients (1%), CRNMB in two patients (1%), and one death (0.5%) was identified; no thromboembolic events occurred. Prior to propensity score matching (PSM), post-procedure LMWH with or without pre procedure LMWH was associated with the composite outcome of MB and CRNMB (P = 0.034), although not with MB or CRNMB individually. After stepwise regression and PSM analyses, no significant differences in bleeding outcomes were observed between patients who received LMWH bridging and those who did not. Our findings indicate that although adverse thrombotic events were rare and use of post-procedure LMWH bridging was significantly associated with a small absolute increased risk of bleeding, it was not significant after PSM. Larger prospective studies are needed to better inform antithrombotic management guidelines for patients with aortic MHVs undergoing gastrointestinal endoscopy.

Post-pulmonary embolism syndrome (PPES) encompasses a diverse spectrum of long-term complications that are associated with persistent dyspnea, exercise intolerance, and a decrease in quality of life. The PPES constellation ranges from life-threatening conditions such as chronic thromboembolic pulmonary hypertension (CTEPH) to nonlife-threatening but still debilitating conditions such as chronic thromboembolic pulmonary disease (CTED) or post-PE deconditioning. The safety and efficacy of exercise and cardiopulmonary rehabilitation programs to prevent and manage these symptoms in PPES has not been well established. Herein, we review contributors to PPES and synthesize the evidence for exercise training after PE to treat and prevent PPES.

Abstract Guidelines recommend placement of inferior vena cava filters (IVCFs) in patients with acute proximal lower extremity deep vein thrombosis (DVT) and a contraindication to anticoagulation. IVCF placement during pregnancy or immediately postpartum presents technical challenges and is not extensively described in the existing literature. This study aimed to describe the use of IVCFs in the obstetric population along with outcomes related to filter placement. Retrospective chart review of all patients at Mayo Clinic from 2001 to 2020 with an IVCF at the time of conception or who underwent placement during pregnancy/postpartum. About 24 pregnancies in 23 women (mean age 26.3 years, range 18–41) were included: 5 (21%) with IVCF placement prior to pregnancy, 7 (29%) during pregnancy, and 12 (50%) during postpartum. IVCFs placed during pregnancy were frequently in the suprarenal position, in 5 (71%) cases. Meanwhile, 16 (94%) were deployed in an infrarenal position prior to pregnancy and postpartum. Complications included multiple attempts to remove the IVCF (n = 2), severe angulation (n = 4), embedded struts (n = 3), fracture (n = 1), and one case of cardiac tamponade (n = 1). Complications were more common when placement was performed prior to pregnancy or during pregnancy (2, 40% and 4, 57% respectively) versus postpartum (2, 17%). IVCF placement prior or during pregnancy/postpartum is uncommon and is associated with a high incidence of complications, although most did not fundamentally impact clinical outcomes. While IVCFs remain an option for clinicians treating pregnant and postpartum patients, these should be considered a last resource.

Abstract Background Ankle-brachial indices (ABI) predict mortality and major cardiovascular events (MACE); however, they are unable to assess the severity of peripheral artery disease in patients with non-compressible vessels. Toe brachial indices (TBI) are less affected by non-compressibility and could be good predictors of cardiovascular morbidity and mortality. Purpose To evaluate the predictive value of TBI for MACE and all-cause mortality in a large population. Methods The initial ABIs and TBIs of all patients referred to a noninvasive vascular laboratory were obtained. We categorized patients based on the worse TBI from either leg, and each patient was classified as normal (>0.8), borderline (0.8-0.61), mild-moderate PAD (0.6 - 0.21) and severe PAD (≤0.2). MACE occurring after the study were identified using ICD9/10 and procedural CPT codes and included myocardial infarction, coronary revascularization, or stroke. Survival analysis was performed using the Kaplan-Meier method with log-rank test to compare survival curves between groups. Results Of 13551 patients, we excluded 643 (5%) in whom TBI could not be obtained. Patient characteristics can be found in Table 1. There were 4,924 MACE and 3,125 deaths during the median follow up time of 8.39 years (Table1). There was a significant difference of MACE incidence (p <0.001) and mortality (p<0.001) by TBI categories, and the curves separate before the 1-year mark (Figure 1A and B). Conclusion TBI is a good predictor of MACE and all-cause mortality in the short and long term and can be obtained in 95% of patients.

Abstract Background Antiphospholipid syndrome (APS) is diagnosed when vascular thrombosis or pregnancy morbidity occurs in the presence of persistent antiphospholipid antibodies (aPL). Although IgM-isotype antibodies are part of the laboratory criteria, their clinical value remains uncertain. We evaluated real-world aPL testing patterns to quantify the prevalence of isolated IgM positivity. Methods We analyzed aPL testing data across the Mayo Clinic sites between January 2006 and July 2025, lined up with the publication of the revised Sapporo (Sydney) classification criteria. For each patient, we identified the first time in which any aPL test was performed. We assessed available results for Lupus anticoagulant (LA), anticardiolipin (aCL) isotypes IgG and IgM, and anti–beta 2 glycoprotein (B2GP1) isotypes IgG and IgM. Positivity rates were calculated for each marker, and a subgroup of patients who had results for all three test categories at the initial workup was identified. In this cohort, we assessed the distribution of single, double, and triple positivity. We also quantified the number and percentage of patients who were positive only for IgM isotypes (aCL or B2GP1), with negative LA and IgG at initial testing. Antibodies were considered positive based on international criteria and internal standards. aCL and B2GP1 were positive if ≥40 units. LA positivity followed ISTH SSC guidelines, requiring demonstration of a phospholipid-dependent inhibitor in the following assays: screening, mixing, and confirmatory steps in DRVVT or aPTT-based platelet neutralization procedure (PNP), Staclot LA delta and HEX LA delta assays. Criteria for a positive result was as follows: DRVVT: prolonged screen and inhibited mix with screen/confirm ratio >1.2; Staclot LA delta: >7 seconds; PNP: shortening of the APTT clotting time with PNP by ≥5 seconds before 2023 and ≥2 seconds thereafter; HEX LA delta >13 seconds. Results A total of 99,814 unique patients underwent testing for at least one aPL marker. The most frequently tested was LA (n = 75,085), with a positivity rate of 10.29% (7,730/75,085). Among antibody isotypes, positivity rates were 1.2% (846/69,539) for aCL IgG, 1.7% (1,198/69,640) for aCL IgM, 1.9% (732/37,791) for B2GP1 IgG, and 2.0% (762/37,601) for B2GP1 IgM. Among the 30,274 patients who underwent simultaneous testing for LA, aCL IgG/IgM, and B2GP1 IgG/IgM, 1.3% (n = 407) were triple-positive, 1.4% (n = 427) were double-positive, and 9.9% (n = 3,009) had a single positive marker. The remaining 87.3% (n = 26,431) tested negative for all three. Of the 3,009 patients with only one positive marker, 9.8% (n = 296) were positive exclusively for aCL IgM, and 7.4% (n = 224) were positive exclusively for B2GP1 IgM. Among all fully tested patients, 2.2% (668/30,274) were positive for only IgM isotypes (either aCL or B2GP1) in the absence of IgG and LA positivity. Specifically, 0.9% (n = 296) were exclusively positive for aCL IgM and 0.7% (n = 224) for B2GP1 IgM. Additionally, 0.5% (n = 148) were simultaneously positive for both aCL IgM and B2GP1 IgM, without associated IgG or LA markers. Had only IgG and LA been assayed, 17.4 % (668/3843) of initially positive patients—and one-third of those classified as triple-positive—would have been missed. Conclusion Within this large-scale analysis of real-world APS test ordering practice, less than one-third of orders included a comprehensive characterization. Isolated IgM positivity, defined as aCL or B2GP1 IgM in the absence of IgG and LA, was infrequent yet represents a sizable proportion of initial positive aPL testing. How these results impact APS diagnosis and management of APS requires further study.

Abstract Background Plantar vein thrombosis is a rare vascular condition typically presenting with unilateral plantar foot pain and edema. Of interest to the musculoskeletal clinician, mechanical trauma to the plantar foot has been cited as a risk factor for development of these thrombi. Objective To assess the demographics, presenting history, risk factors, treatment protocols, and long‐term sequelae of patients with plantar vein thrombosis secondary to increased mechanical trauma. Design Retrospective chart review. Setting Tertiary care center. Participants Adult patients with mention of plantar vein thrombosis in imaging impressions. Main Outcome Measures Primary outcome measure was determination of the demographic and clinical characteristics of plantar vein thrombosis in patients with mechanical trauma as a preceding risk factor. Secondary outcome was evaluation of treatment options in this patient population. Results Between 2005 and 2023, nine patients at a single institution were diagnosed with plantar vein thrombosis through imaging and were determined to have developed the thrombus due at least in part to mechanical trauma. Patients typically presented with localized plantar foot pain and foot edema. Diagnosis was made via magnetic resonance imaging or ultrasound. The most frequent treatment was therapeutic anticoagulation but initial conservative treatment with serial ultrasound resulted in conversion to anticoagulation in only one patient. Among those patients with mechanical trauma as an inciting factor, the only noted complication was propagation of the thrombosis in one patient. Conclusions Although rare, plantar vein thrombosis should be considered by the musculoskeletal clinician in the differential diagnosis of unilateral plantar foot pain. Treatment of these thrombi is most commonly therapeutic anticoagulation, but in the absence of additional high‐risk factors serial ultrasound evaluations may be an adequate first line treatment due to the overall minimal risk of thrombosis propagation.

ABSTRACT BACKGROUND Platelet factor 4-polyanion enzyme-linked immunosorbent assays (ELISAs) are considered highly sensitive for diagnosing heparin-induced thrombocytopenia (HIT), such that current practice guidelines recommend use of ELISA-negative results to exclude HIT. Once HIT is ruled out, alternative, non-heparin-based anticoagulant treatments are ceased, and heparin reintroduction frequently occurs. METHODS Antigen-based and PF4-dependent functional testing were used to study PF4/polyvinyl sulfonate ELISA-negative platelet-activating antibodies in HIT-suspected patients and mice immunized with PF4/heparin. RESULTS Three patients with clinical presentations consistent with HIT tested negative in an ELISA using PF4-polyvinylsulfonate (PF4/PVS), an antigenic target very commonly used for HIT antibody detection. All three patients demonstrated PF4-dependent platelet activation in functional testing that was sensitive to blockade of platelet FcγRIIa receptors and inhibited by high concentrations of heparin, consistent with pathogenic HIT antibodies. Functional testing-based screening of 500 ELISA-negative patients identified three patients whose sera activated platelets in a PF4- and FcγRIIa-dependent manner, and had clinical histories consistent with HIT. Five of the six ELISA-negative HIT patients were re-exposed to heparin, which precipitated a decrease in platelet counts in all re-exposed patients, and one patient developed a new thrombus. To advance the study of ELISA-negative HIT antibodies, mice were immunized with PF4/heparin, and functional and antigenic assays were simultaneously used to successfully identify an ELISA-negative, PF4-dependent platelet-activating murine monoclonal antibody that recapitulated the serological characteristics of ELISA-negative HIT patients. CONCLUSIONS Recognition of ELISA-negative HIT is critical to avoid harm due to the cessation of alternative anticoagulation therapy and re-exposure of these patients to heparin.