Author`s Reply.

To the Editor,

We would like to thank the authors for their interest in our article titled “Mitral valve and right ventricular thrombi possibly caused by heparin-induced thrombocytopenia” and for taking time to express their opinions (1). In the authors’ letter to the editor, they mention potential concerns with the diagnosis and management of HIT.

Anticoagulation is the cornerstone of treatment for acute pulmonary embolism (PE). Unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), and fondaparinux are the main options as anticoagulants in the treatment of acute PE. We totally agree with the authors. Both 2014 and 2019 ESC Guidelines on the diagnosis and management of acute PE recommend that if anticoagulation is parenterally initiated, LMWH or fondaparinux should be used in most patients (Class I-A) (2, 3). However, it is important to note that the use of UFH in the treatment of low-to-moderate PE patients is not contraindicated.

Fondaparinux is an anticoagulant pentasaccharide that specifically inhibits activated factor X. Major cardiovascular guidelines regarding acute PE recommend fondaparinux as one of the first-line treatment options in low- to moderate-risk patients (3). Moreover, a recent study has indicated that fondaparinux has efficacy and safety equivalent to those of argatroban and danaparoid in patients with suspected heparin-induced thrombocytopenia (HIT) (4). On the basis of these recommendations, fondaparinux is subcutaneously administered at a dose of 5 mg per day in patients weighing <50 kg (our patient weighed 48 kg).

In the case report, we have mentioned that a detailed evaluation of the patient for the presence of cancer was performed by an oncologist. Malignancy markers were negative, and positron emission tomography/computed tomography (CT) and whole-body CT were evaluated in detail. Moreover, in this case report, we specifically mentioned the necessity of platelet function test or serological tests for confirming the diagnosis of HIT. This is the major limitation of our case report.