Bleeding events during anticoagulation in patients with hereditary hemorrhagic telangiectasia

Pharmacogenomic Considerations for Anticoagulant Prescription in Patients with Hereditary Haemorrhagic Telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia that commonly results in bleeding but with frequent indications for therapeutic anticoagulation. Our aims were to advance the understanding of drug-specific intolerance and evaluate if there was an indication for pharmacogenomic testing. Genes encoding proteins involved in the absorption, distribution, metabolism, and excretion of warfarin, heparin, and direct oral anticoagulants (DOACs) apixaban, rivaroxaban, edoxaban, and dabigatran were identified and examined. Linkage disequilibrium with HHT genes was excluded, before variants within these genes were examined following whole genome sequencing of general and HHT populations. The 44 genes identified included 5/17 actionable pharmacogenes with guidelines. The 76,156 participants in the Genome Aggregation Database v3.1.2 had 28,446 variants, including 9668 missense substitutions and 1076 predicted loss-of-function (frameshift, nonsense, and consensus splice site) variants, i.e., approximately 1 in 7.9 individuals had a missense substitution, and 1 in 71 had a loss-of-function variant. Focusing on the 17 genes relevant to usually preferred DOACs, similar variant profiles were identified in HHT patients. With HHT patients at particular risk of haemorrhage when undergoing anticoagulant treatment, we explore how pre-emptive pharmacogenomic testing, alongside HHT gene testing, may prove beneficial in reducing the risk of bleeding and conclude that HHT patients are well placed to be at the vanguard of personalised prescribing.

Antiplatelet and anticoagulant therapies in hereditary hemorrhagic telangiectasia: A large French cohort study (RETROPLACOTEL)

BACKGROUND

It is unclear whether hereditary hemorrhagic telangiectasia (HHT) patients can tolerate antithrombotic therapies (AT) including antiplatelet (AP) and/or anticoagulant (AC) agents.

OBJECTIVES

Primary endpoint was tolerance to AT in HHT. Secondary endpoints were to identify factors associated with major bleeding events (MBE) and premature discontinuation of AT.

METHODS

Retrospective multicenter study in French national HHT Registry patients exposed to AT.

RESULTS

We included 126 patients with 180 courses of AT. Median follow-up was 24 [11-52] months. Mean age was 65.6 ± 13.1 years. The first 3 months of AT exposure had an increased risk of hospitalization for hemorrhage (p < 0.001) and transfusions (p < 0.001). MBE (n = 63) occurred more frequently in the first 3 months of AT exposure (p < 0.001). Premature discontinuation of AT occurred in 61 cases. Rate of premature discontinuation was 29 % under both AP and AT therapy but significantly higher under dual AP therapy (n = 4/7, 57 % p = 0.008). Risk factors for MBE were: age ≥ 60 years (HR 2.34 [1.12;4.87], p = 0.023), prior hospitalization in the 3 months before starting AT for hemorrhage (HR 3.59 [1.93;6.66], p < 0.001) or transfusion (HR 3.15 [1.61;6.18], p = 0.001), previous history of gastro-intestinal bleeding (HR 2.71 [1.57;4.65], p < 0.001) or MBE (HR 4.62 [2.68;7.98], p < 0.001). Frequency of MBE did not differ between groups except for a higher risk in the dual AP group (HR 3.92 [1.37;11.22], p = 0.011).

CONCLUSION

Tolerance of AC or AP therapy was similar in HHT population but not dual AP therapy. We identified risk factors for MBE occurrence or premature discontinuation under AT.

Safety, tolerability, and effectiveness of anticoagulation and antiplatelet therapy in hereditary hemorrhagic telangiectasia

BACKGROUND

Antithrombotic therapy (anticoagulation and antiplatelet therapy) is frequently needed in patients with hereditary hemorrhagic telangiectasia (HHT); however, data describing and guiding its use are very limited.

OBJECTIVES

To investigate the safety, tolerability, and effectiveness of antithrombotic therapy in HHT in a cohort large enough to compare agents, evaluate for baseline predictors of premature discontinuation, and evaluate hematologic support requirements and healthcare utilization before and after antithrombitc therapy initiation.

METHODS

We performed a multicenter observational cohort study characterizing the outcomes of antithrombic therapy in adults with HHT.

RESULTS

A total of 119 patients with HHT with 187 discrete antithrombotic therapy episodes were included. Of these, 59 patients (50%) dose-reduced and/or prematurely discontinued therapy (including 52 patients [44%] who discontinued) due to worsened bleeding complications. Initiation at reduced dose intensity had a similar premature discontinuation rate (49%) as initiation at standard dose intensity (43%). In a multivariable logistic model, a history of gastrointestinal bleeding was associated with 3.25-fold odds of discontinuation (p = .001). Hemoglobin was significantly lower (10.8 g/dL vs 12.2 g/dL, p < .001), and the need for hematologic support (intravenous iron and/or red blood cell transfusion) was significantly higher (29 patients vs 12 patients, p = .004) in the 3 months after antithrombotic therapy initiation vs the 3 months before; emergency department visits and hospital admissions due to bleeding also increased. The rates of dose-reduction and/or premature discontinuation were similar regardless of the anticoagulant class (warfarin, 46%; heparin-based, 48%; direct oral anticoagulants, 44%) or with multiple simultaneous agents (44%) but were slightly lower with single-agent antiplatelet therapy (37%). Thromboembolism despite receiving antithrombotic therapy was common (18 patients, 15%) with varying outcomes.

CONCLUSION

Antithrombotic therapy is challenging in HHT, resulting in objectively higher morbidity and health care utilization from worsened bleeding. Discontinuation rates approached 50% regardless of the dose intensity at initiation or type of antithrombotic agent used and were higher in patients with a gastrointestinal bleeding history.