Discussion
Since HHT is a rare disorder, the natural history of VTE in these patients, and the optimal therapy are not well known. The only two studies that analyze the effect of anticoagulation in HHT patients were not based on objectively confirmed diagnosis and outcomes of VTE but on on-line surveys [
12,
13]. The first one was an on-line questionnaire about the use of antiplatelet or anticoagulant agents in HHT patients [
12]. A worsening of their usual epistaxis was referred in 86 (57.3%) of 150 patients with HHT who received anticoagulant therapy for different reasons [
12]. In the second study, 20% of 20 patients with self-reported diagnosis of VTE who received anticoagulant therapy had to withdraw anticoagulation because of bleeding [
13].
Our findings, obtained from the largest series of HHT patients with objectively confirmed VTE, reveal that one in every 3 (35%) patients bled during the course of anticoagulant therapy, though no bleed was fatal. This may be due to the fact that most bleeds came from nasal or GI tract telangiectasia and not from large vascular malformations (i.e. in the liver, lung or brain), that are common in HHT patients. The ESS seems to detect those patients at an increased risk to develop epistaxis, as all four patients with epistaxis during anticoagulation had a ESS > 4. ENT management to optimize measures to reduce epistaxis could allow to better tolerate anticoagulation [
3,
20]. Other options, such as tranexamic acid, topical or systemic estrogens, thalidomide or bevacizumab, should be weighted against the risk of VTE for these drugs [
3,
21‐
24].
Eighteen patients in our cohort (78%) had prior epistaxis, five had renal insufficiency, three had documented angiodisplasia in the GI tract and one patient had a gastroduodenal ulcer. To what extent the use of anticoagulant therapy could have influenced on the risk for bleeding is unknown. Two of the three patients with major epistaxis in the 30 days before the index VTE repeated epistaxis during the course of anticoagulation: one of these had a major re-bleeding. Then, we cannot assume that repeated epistaxis that happened during the course of anticoagulant therapy were exclusively related to anticoagulation, as epistaxis is an inherent feature of HHT [
3,
4,
9]. However, anticoagulation can increase the duration and severity of epistaxis [
12]. Unfortunately, we have no monitoring ESS during anticoagulant treatment to analyze this association.
In spite of the bleeding risk, some HHT patients also suffer from thrombotic complications [
10,
25‐
27]. Six patients in our cohort developed the index VTE after being immobilized for an acute medical illness and two had recent surgery, but only three of them did receive VTE prophylaxis. We hypothesize that the attending doctors might have been concerned about the risk for bleeding. In the on-line survey of HHT patients with self-reported VTE, 76% of them had a risk factor for VTE [
13]. There is consistent evidence on the reduction of VTE using prophylaxis in at-risk patients, with very low increase in the risk for bleeding [
28], but we do not know the potential benefit of VTE prophylaxis in at-risk patients with HHT. Further research is necessary to define prophylactic strategies in this frequently hospitalized HHT population. For these provoked VTE events, anticoagulant therapy for only 3 months is recommended [
29].
Our study has a number of limitations. First, the proportion of patients with HHT in our cohort was most likely conservative because some cases might have been missed. Second, we were not able to retrospectively collect genetic study and reassess Curaçao criteria in all patients [7, 8]. Nonetheless, the high percentage of recurrent epistaxis and first degree relatives with HHT in our patients, support the HHT diagnosis. Third, our study was not designed for assessment of comparative effectiveness of management strategies in patients with HHT. Since all patients with HHT in our cohort received anticoagulant therapy, we are unable to compare the potential advantages of the different therapeutic approaches. However, our study provides important insights into the outcomes of HTT patients with VTE. Fourth, the ESS has been retrospectively calculated after some time, being a likely cause of ascertainment bias. Finally, although many of the studies from the RIETE registry were designed with broad or detailed a priori plans, HHT is a rare disease and the decisions to explore several of the data elements were based on post-hoc plans and analyses. However, to our knowledge, these data represent the largest series of patients with HHT and objectively confirmed VTE. Moreover, the main strengths of our study are the strict and objectively diagnostic criteria for VTE, the long-term follow-up period and the objectively established outcomes reported (bleeding, recurrent symptomatic VTE and mortality).
Acknowledgements
We thank the RIETE Registry Coordinating Center, S&H Medical Science Service, for their quality control data, logistic and administrative support and Prof. Salvador Ortiz, Universidad Autónoma Madrid and Silvia Galindo, both Statistical Advisors in S&H Medical Science Service for the statistical analysis of the data presented in this paper.
Coordinator of the RIETE Registry: Manuel Monreal.
RIETE Steering Committee Members: Paolo Prandoni, Benjamin Brenner and Dominique Farge-Bancel.
RIETE National Coordinators: Raquel Barba (Spain), Pierpaolo Di Micco (Italy), Laurent Bertoletti (France), Sebastian Schellong (Germany), Inna Tzoran (Israel), Abilio Reis (Portugal), Marijan Bosevski (R. Macedonia), Henri Bounameaux (Switzerland), Radovan Malý (Czech Republic), Peter Verhamme (Belgium), Joseph A. Caprini (USA), Hanh My Bui (Vietnam).
RIETE Registry Coordinating Center: S & H Medical Science Service.
Members of the RIETE Group:
SPAIN: Adarraga MD, Agud M, Aibar MA, Alcalde-Manero M, Alfonso J, Amado C, Arcelus JI, Ballaz A, Barba R, Barbagelata C, Barrón M, Barrón-Andrés B, Blanco-Molina A, Camon AM, Cañas I, Castro J, Cerdà P, de Miguel J, del Toro J, Demelo P, Díaz-Pedroche C, Díaz-Peromingo JA, Domínguez IM, Escribano JC, Falgá C, Fernández-Capitán C, Fernández-Criado MC, Fidalgo MA, Flores K, Font C, Font L, Furest I, García MA, García-Bragado F, García-Raso A, Gavín-Blanco O, Gavín-Sebastián O, Gil-Díaz A, Godoy-Díaz D, Gómez V, Gómez-Cuervo C, González-Martínez J, Grau E, Guirado L, Gutiérrez J, Hernández-Blasco LM, Jara-Palomares L, Jaras MJ, Jiménez D, Joya MD, Jou I, Lalueza A, Lecumberri R, Lima J, Llamas P, Lobo JL, López-Jiménez L, López-Meseguer M, López-Miguel P, López-Núñez JJ, López-Reyes R, López-Sáez JB, Lorente MA, Loring M, Lumbierres M, Madridano O, Maestre A, Marchena PJ, Martín-Martos F, Martínez-Baquerizo C, Martínez-García MA, Mellado M, Moisés J, Monreal M, Morales MV, Muñoz-Blanco A, Nieto JA, Núñez MJ, Olivares MC, Olivera PE, Ortega C, Osorio J, Otalora S, Otero R, Panadero-Macia M, Parra V, Pedrajas JM, Pellejero G, Pérez-Ductor C, Pérez-Rus G, Peris ML, Pesantez D, Porras JA, Riera-Mestre A, Rivas A, Rodríguez-Cobo A, Rodríguez-Matute C, Rosa V, Rubio CM, Ruiz-Artacho P, Ruiz-Sada P, Sahuquillo JC, Sala-Sainz MC, Salgueiro G, Sampériz A, Sánchez-Martínez R, Sánchez-Muñoz-Torrero JF, Seguí E, Soler S, Suárez S, Suriñach JM, Tolosa C, Torres MI, Trujillo-Santos J, Uresandi F, Valero B, Valle R, Vidal G, Vilar C, Villares P, ARGENTINA: Gutiérrez P, Vázquez FJ, Vilaseca A, BELGIUM: Vanassche T, Vandenbriele C, Verhamme P, CZECH REPUBLIC: Hirmerova J, Malý R, ECUADOR: Salgado E, FRANCE: Benzidia I, Bertoletti L, Bura-Riviere A, Debourdeau P, Courtois MC, Farge-Bancel D, Helfer H, Hij A, Mahé I, Moustafa F, GERMANY: Schellong S, ISRAEL: Braester A, Brenner B, Tzoran I, ITALY: Bilora F, Bortoluzzi C, Ciammaichella M, Dentali F, Di Micco P, Ferrazzi P, Imbalzano E, Lodigiani C, Maida R, Mastroiacovo D, Mumoli N, Pace F, Pesavento R, Pomero F, Prandoni P, Quintavalla R, Rocci A, Rota L, Siniscalchi C, Tiraferri E, Tufano A, Visonà A, Vo Hong N, Zalunardo B, LATVIA: Kalejs RV, Kigitovica D, Skride A, REPUBLIC OF MACEDONIA: Bosevski M, Zdraveska M, SWITZERLAND: Bounameaux H, Mazzolai L, USA: Caprini JA, Tafur AJ, VIETNAM: Bui HM.