Abstract

Introduction

An intracardiac thrombus is a rare yet potentially life-threatening condition in the paediatric population. This study aimed to describe the clinical characteristics, diagnostic findings, treatment strategies, and outcomes of paediatric patients diagnosed with intracardiac thrombus.

Materials and Methods

A retrospective study was conducted including patients aged 0–17 years who were diagnosed with intracardiac thrombus between February 2020 and May 2025 at our paediatric cardiology clinic. Demographic characteristics, clinical presentation, echocardiographic findings, treatment modalities, and clinical outcomes were reviewed. The study was retrospective and observational in design.

Results

Ten patients were identified with a median age of 3 years (range: 10 days to 17 years), of whom seven were female (70%). The most common thrombus location was the right atrium (70%). Six patients (60%) had a history of central venous catheterization. Anticoagulation therapy was initiated in all patients, while three patients (30%) required surgical thrombectomy due to an inadequate response to medical treatment. Complications included a cerebrovascular event in one patient, pulmonary embolism in two patients, and one death.

Conclusion

Intracardiac thrombus in children is associated with multiple risk factors. Although anticoagulation therapy remains the primary treatment option, surgical intervention may be required in selected cases. The absence of a standardized treatment duration highlights the importance of individualized management and the need for further multicentre studies.

Introduction

An intracardiac thrombus is a rare yet potentially life-threatening condition in the paediatric population. Because large-scale studies are lacking, knowledge of this condition relies heavily on case series and isolated reports, leaving its true incidence in children poorly defined (1, 2). Multiple predisposing factors have been characterised, including prematurity, cyanotic heart disease, sepsis, malignancy, central or umbilical venous catheterization, surgery, and both acquired and inherited thrombophilias (3, 4). Echocardiography is the diagnostic modality of choice due to its non-invasive nature, widespread accessibility, and high sensitivity (5). In contrast to the adult population, where intracardiac thrombi frequently localise to left-sided cardiac chambers, paediatric presentations demonstrate a predilection for right heart involvement (6).

Therapeutic approaches in children remain largely derived from adult protocols and are influenced by multiple variables such as patient age, clinical syndrome, thrombus dimensions, anatomical location, and degree of mobility (2). Anticoagulation is still considered the first-line therapy, although surgical thrombectomy or pharmacological thrombolysis may be warranted in selected cases. The optimal duration of anticoagulation in children, however, remains a matter of debate (1).

Given the relative rarity of paediatric intracardiac thrombus and its documentation primarily through small case series, there is a need for thorough characterisation of its varied clinical presentations. Our study, therefore, aims to contribute to the existing literature by detailing the heterogeneous aetiologies, management strategies, and clinical outcomes in a diverse series of ten paediatric cases.

Materials and Methods

We conducted a retrospective review of all patients aged 0–17 years diagnosed with intracardiac thrombus between February 2020 and May 2025 at the Paediatric Cardiology Department of Necmettin Erbakan University Faculty of Medicine.

Patients were excluded if they were older than 17 years, had received anticoagulant therapy prior to diagnosis, or had an intracardiac mass subsequently confirmed as non-thrombotic. Transthoracic echocardiography was used for both diagnosis and follow-up assessment.

We collected demographic data, clinical presentations, echocardiographic characteristics, treatment modalities, and outcomes for analysis. A thrombophilia panel was performed in eight patients.

Statistical Analysis

Statistical analysis was conducted on SPSS version 18.0 (SPSS Inc., Chicago, Illinois, United States of America).

Results

Between February 2020 and May 2025, ten paediatric patients were diagnosed with intracardiac thrombus at our institution. The median age was 3 years (range: 10 days to 17 years), and seven patients (70%) were female.

Six patients had a history of central venous catheterisation, whilst an atrial septal defect was identified in three patients (30%). One patient was in the third month following atrial septal defect repair and was not receiving aspirin therapy at the time of thrombus detection. Among the patients with prior catheterisation, two had undergone plasmapheresis and one had a surgical history related to extremity fracture repair. All relevant demographic, clinical, and echocardiographic data are summarised in Table 1.

Echocardiography showed that thrombi were located predominantly in the right atrium (n=7, 70%). In the remaining patients, thrombi were found in the right ventricle (n=1), the left ventricle (n=1), and at the junction of the inferior vena cava and the right atrium (n=1). Ventricular function was preserved across the cohort, with a mean left ventricular ejection fraction of 65% (range: 52–73%) and a mean fractional shortening of 36% (range: 24–41%). Detailed echocardiographic findings are presented in Table 1. Representative images are shown in Figure 1, and the pre- and post-treatment views for Case 9 are shown in Figure 2.

Treatment and Outcomes

Seven patients were treated with a combination of aspirin and low molecular weight heparin, while three received low molecular weight heparin monotherapy. One patient (Case 10) was treated with systemic tissue plasminogen activator for a massive pulmonary embolism. The median overall treatment duration was 90 days (range: 18 days to 12 months), with low molecular weight heparin administered for a median of 40 days and aspirin for a median of 180 days. In Case 9, aspirin therapy was initiated but discontinued on day three due to tinnitus, with subsequent management consisting of low molecular weight heparin for 14 days followed by dipyridamole for three months.

Three patients (30%) with right atrial thrombi who did not respond to medical therapy required surgical thrombectomy. Significant complications occurred, including a cerebrovascular event in one patient, pulmonary embolism in two, and one death. Treatment regimens and clinical outcomes are detailed in Table 2.

We performed thrombophilia screening in eight patients. Genetic analysis identified a heterozygous methylenetetrahydrofolate reductase c.1298A>C polymorphism in two patients. Coagulation protein deficiencies were also detected: two cases of isolated protein C deficiency, one case of combined protein C and S deficiencies, and one case of factor X deficiency.

Discussion

This case series describes the diagnosis, management, and outcomes of ten paediatric patients with intracardiac thrombus. The primary contribution of our study lies in its documentation of the significant clinical heterogeneity observed in this population, reinforcing the need for individualized care. While most literature is limited to fewer cases, provides broader insight into the diverse risk factors that clinicians may encounter, ranging from central venous catheter use to underlying thrombophilias.

Previous studies have reported varying demographic patterns. John et al. (1) described a mean age of 8.8 years among 31 paediatric patients, with a male predominance (22 males, 9 females). Ozkutlu et al. (7) reported ages ranging from 7 days to 5 years, again with male predominance (8 males, 3 females. Our series demonstrated a lower median age of 3 years and female predominance, highlighting the demographic variability in this condition.

Common aetiological risk factors include prematurity, cyanosis, bacteraemia, malignancies, nephrotic syndrome, indwelling catheters, cardiac surgeries, and acquired or hereditary thrombophilias (3, 4). Agarwal et al. (6) identified central venous catheter use (73%), congenital heart disease (41%), malignancies (25%), and active infections (24%) as leading risk factors in 51 paediatric patients. In contrast to adults, where intracardiac thrombus typically associates with myocardial infarction, dilated cardiomyopathy, and atrial arrhythmias (2), our series identified similar paediatric risk factors including leukaemia, dilated cardiomyopathy, prematurity, hypoxaemia, sepsis, central venous catheter use, and recent surgery.

Echocardiography remains the diagnostic modality of choice, offering non-invasive, accessible, and rapid assessment with reported sensitivity and specificity of 95% and 86%, respectively (5). Two-dimensional transthoracic echocardiography provided detailed information regarding thrombus location, size, relationship to adjacent structures, and impact on cardiac function. It proved equally valuable for monitoring thrombus resolution and guiding treatment duration. Consistent with Agarwal et al. (6), who reported right atrial involvement in 59% of cases, the right atrium was the predominant site in our series.

The incidence of catheter-related venous thrombosis in children ranges between 25% and 40%, whereas right atrial thrombus prevalence in patients with central venous catheters ranges from 5.4% to 12.5% (2). The free tip of the central venous catheter can cause endothelial injury, promoting thrombus formation. The risk is higher when the catheter tip lies within the right atrium compared to the superior vena cava (8). The catheter tip can cause endothelial injury, promoting thrombus formation, with higher risk when positioned within the right atrium compared to the upper caval vein (8). In our cohort, 60% had prior central venous catheter placement, with all associated thrombi located in the right heart. Clinicians should maintain high suspicion for right atrial thrombus in patients with prolonged hospitalisation and central venous catheters, particularly when new symptoms develop, and should promptly perform an echocardiographic evaluation.

Intracardiac thrombus prevalence in dilated cardiomyopathy ranges from 6% to 53%, most commonly affecting the left ventricle (2). Case 2 in our series presented with acute cerebral infarction, with echocardiography revealing dilated cardiomyopathy and a 14.2×4.4-millimetre mural thrombus at the left ventricular apex. Thrombophilia screening revealed protein C deficiency, and the thrombus resolved with medical treatment. Surgical thrombectomy is generally recommended for left-sided, pedunculated thrombi exceeding 2 centimetres due to increased embolization risk (3). Our patient’s smaller, mural thrombus was appropriately managed medically.

The 2024 American Society of Haematology/International Society on Thrombosis and Haemostasis guidelines recommend anticoagulation for paediatric patients with right atrial thrombus who have high-risk features and low bleeding risk (9). Determining optimal anticoagulation duration remains challenging. The 2012 American College of Chest Physicians guidelines recommend at least three months of anticoagulation for right atrial thrombi but provide no guidance for longer durations (1). Our patients received treatment for a median of 90 days.

Protein C and its cofactor protein S are important natural anticoagulants, with deficiencies being either congenital or acquired (7, 10). Ozkutlu et al. (7) reported protein C deficiency as a causative factor in 3 of 11 paediatric patients (7). Our series identified protein C deficiency in two cases and concurrent protein C and S deficiency in one case. Although these patients had other prothrombotic conditions, we consider these deficiencies as contributing factors.

Given the heterogeneity of intracardiac thrombi in paediatric patients, future research should focus on developing standardised, evidence-based clinical decision tools. A morphology-based risk scoring system could aid in stratifying embolic risk and guiding therapeutic intensity. An age- and site-specific anticoagulation algorithm may optimise treatment duration and outcomes.

Study Limitations

This study has several limitations inherent to its design. As a retrospective, single-centre report, it is limited by a small sample size, which precludes robust statistical analysis. However, this focus on a small cohort allows for a detailed descriptive analysis of a clinically heterogeneous group, which is the study’s principal strength. Besides, the diversity of patient comorbidities and the individualized treatment approaches serve as confounding factors that prevent definitive conclusions about therapeutic efficacy. The reliance on echocardiography as the primary diagnostic tool is another limitation, as its sensitivity may vary for certain thrombus locations or morphologies. Finally, the limited long-term follow-up restricts our assessment of delayed thrombotic events and late complications. Our findings, while not generalizable, can provide valuable, hypothesis-generating insights into a rare paediatric condition and highlight the spectrum of real-world clinical challenges.

Conclusion

Intracardiac thrombus is a rare but serious condition in paediatric patients associated with significant morbidity and mortality. The clinical course varies depending on the underlying aetiology and presentation, highlighting the need for multidisciplinary care. Current management is primarily extrapolated from adult data, forcing clinicians to tailor treatment individually. The heterogeneous nature of this condition underscores the need for larger, multicentre studies to clarify optimal management strategies for this vulnerable population.