Due to its rarity, risk factors for endocarditis due to Candida spp. are not well established. One multivariable analysis suggests only valvular heart disease as an independent risk factor. Other possible risk factors include prosthetic heart valves, immunosuppression, diabetes mellitus, prolonged antibiotic therapy, intravenous drug use, previous cardiac surgery, vascular access lines and CIED [8, 9]. The most common Candida species causing endocarditis is C. albicans, followed by C. parapsilosis [3]. The diagnosis of endocarditis due to C. albicans was definite according to the modified Duke criteria. Diagnosis was further supported by the presence of risk factors (pacemaker, immunosuppression due to uncontrolled diabetes mellitus, chronic kidney disease and old age), extensive fungal fingernail infection, absence of other documented sites of active fungal disease explaining the candidemia, as well as significant clinical and laboratory improvement with antifungal treatment. Despite the presence of a pacemaker, our patient did not meet criteria for CIED-related fungal endocarditis, as the cultures from the explanted leads were negative. Primary mural endocarditis due to Candida spp. is very rare, with only nine cases identified in the literature [4, 5]. Primary mural endocarditis of the right atrium due to C. albicans has not been described in the literature and to our knowledge this is the first reported case.

Echocardiography is the main diagnostic tool for investigating right atrial masses [10]. Regarding our patient, the main diagnosis to differentiate was atrial myxoma, which is more common in the left atrium and usually originates from the interatrial septum with a narrow stalk [11, 12]. Atrial myxoma is a slowly growing tumor and the absence of a mass on a TTE seven months prior to the presentation further decreases the possibility of this diagnosis. Malignant cardiac tumors have an invasive nature and are usually associated with significant pericardial effusion and a more aggressive course which did not fit the patient’s description. Metastatic neoplasms are the most common malignant cardiac tumors with aggressive local behavior and often the presence of a primary tumor site, which was not the case for our patient. Angiosarcomas are the most frequent primary malignant cardiac tumors that usually arise from the right atrial free wall near the inferior vena cava but show infiltrative local behavior and often extend to the pericardium and right ventricle [11]. We should also highlight that the echogenicity of the mass with a spongy appearance and vacuoles was characteristic of a vegetation, compared to the compact echogenicity that characterizes many tumors. Another entity to exclude was intracardiac thrombus, which has different echogenicity and is more common in the left auricle, apex and akinetic segments of the left ventricular wall [11, 12].

Regarding the performance of biopsy for histological confirmation of the diagnosis, the patient was evaluated by a heart team taking into account multiple variables. The possibility of infective endocarditis was very high, considering the definite diagnosis from the modified Duke criteria together with the significant clinical and laboratory improvement with antifungal treatment. Another aspect that further supports the diagnosis is that Candida spp. is seven times more common in primary mural endocarditis (14% of cases), compared to the 2% frequency of all infective endocarditis cases [5]. On the other hand, the probability of an alternative diagnosis, such as a cardiac tumor or thrombus, was low, as already highlighted. Furthermore, the risk of performing biopsy was high, considering the elevated EUROSCORE of 33%, presence of severe comorbidities, frailty and patent foramen ovale. For the above reasons, following discussion with the patient and relatives, we decided against performing biopsy for diagnostic purposes.

The management of endocarditis due to Candida spp. is complex and warrants evaluation from a heart team. Based on the 2023 ESC Guidelines, liposomal amphotericin B with or without flucytosine or high-dose echinocandin is the management of choice, while long-term suppressive therapy with fluconazole or voriconazole is recommended, sometimes lifelong. Regarding CIED extraction, it is recommended with class I and grade B evidence in definite and class IIa and grade C evidence in probable CIED involvement [7]. According to expert consensus statements transvenous lead extraction can be performed in vegetations less than 2.5 cm, while larger vegetations require surgical extraction [13,14]. Our patient did not present with clinical or laboratory features of uncontrolled infection, acute heart failure, recurrent pulmonary emboli or other features to warrant cardiothoracic surgery for the purpose of treatment based on the 2023 ESC Guidelines [14]. We should highlight that specific guidelines on the management of primary mural endocarditis due to Candida spp. are lacking, due to the rarity of this entity.