Acute ischemic stroke revealing a huge left atrial pinball thrombus: case report

¹Cardiology Department, Military Training Hospital of Rabat, Rabat, Morroco

^&Corresponding author
Hanaa El Ghiati, Cardiology Department, Military Training Hospital of Rabat, Rabat, Morroco

Introduction    

Ischemic stroke, a leading cause of morbidity and mortality worldwide, often originates from the occlusion of cerebral blood vessels due to thrombotic formations. Thrombi, typically consisting of aggregated platelets, fibrin, and trapped red blood cells, can vary in composition and morphology. This study presents a unique case of ischemic stroke, where transthoracic echocardiography unveiled a pinball-like thrombus within left atrium.

Patient and observation     

Patient information: we report a case of a 59-year-old female with a history of acute ischemic stroke who presented to the emergency room with right hemiplegia and aphasia. Her other comorbidities included hypertension, a long history of atrial fibrillation, and moderate mitral stenosis on vitamin K antagonist. Her international normalized ratio (INR) was not regularly controlled. She had no particular familial history and no relevant past interventions.

Clinical findings: the patient appeared distressed and had difficulty breathing. Her blood pressure was 150/90mmHg, and she was tachycardic with a heart rate of 110bpm. She was tachypneic, with an oxygen saturation of 88% on room air. Cardiac examination showed loud S1 and mid-diastolic murmur. Bilateral basal crackles were present, more pronounced on the left side. No wheezing or ascites. Otherwise, the patient had no signs of right heart failure: no peripheral oedema or hepatomegaly. Neurological examination found an alert patient with dysarthric speech, and profound weakness (1/5) in the right upper and lower extremities, indicating complete hemiplegia; with normal strength (5/5) in the left upper and lower extremities.

Timeline of the current episode: the patient was diagnosed with atrial fibrillation associated with moderate mitral stenosis a few years ago. However, her follow-up was irregular and inconsistent. No echocardiographic findings or INR results were available until she presented with neurological symptoms indicative of an acute ischemic stroke, which revealed a pinball thrombus in the left atrium.

Diagnostic assessment: bedside transthoracic echocardiography confirmed a 44×35 cm free-floating thrombus as shown in Figure 1,Figure 2, behaving like a pinball in the severely dilated left atrium and intermittently obstructing the mitral valve. Severe mitral stenosis (mean gradient=5 mmHg; valve area= 0.8 cm²), diffuse thickening of mitral valve leaflet with restricted opening (rheumatic-like), moderate tricuspid regurgitation, severely dilated left atrium (maximal dimension=5.5 cm), and preserved left ventricular ejection fraction (60%) were found. Non-contrast cerebral CT scan showed a hypodense area in the distribution of the left middle cerebral artery territory, and the absence of hemorrhage.

Diagnosis: acute ischemic stroke, revealing a large pinball thrombus in the left atrium with severe mitral stenosis.

Therapeutic interventions: the patient underwent thrombus removal and mechanical mitral valve replacement.

Follow-up and outcome of interventions: histopathological examination of the removed material revealed a thrombus. The evolution was favorable without complications after 3 months of follow-up. The patient was included in a rehabilitation plan with physical and speech therapy.

Patient perspective: after cardiac surgery, the patient recovered well and was discharged a few days later. She was pleased with the level of care, as her dyspnea had resolved.

Informed consent: informed consent was obtained from the patient for the publication of this case and accompanying images.

Discussion     

The phenomenon of an atrial free-floating ball thrombus was initially identified by Wood in 1814 during an autopsy of a 15-year-old girl suffering from mitral stenosis [1]. Since that time, numerous cases have been documented, largely attributed to the increased use of echocardiography. Most of these cases were linked with atrial fibrillation and mitral stenosis [2]. This aligns perfectly with our case, which also presented with both of these conditions. However, several cases described in the literature occur in a normal mitral valve. Theories about its formation in these cases remain speculative. The precise formation mechanism of a floating ball thrombus is not fully understood. One theory suggests that it originates as a fixed mural thrombus in the left atrial wall, associated with a dilated left atrium and atrial fibrillation, particularly in patients with insufficient anticoagulation therapy [3]. The international normalized ratio (INR) of our patient was not regularly controlled. A free-floating thrombus in the left atrium exposes it to many potential complications. It poses a risk of sudden hemodynamic collapse if it occludes the mitral orifice [4]. Additionally, systemic embolization may occur if the thrombus fragments, which was the case of our patient and was responsible for its acute ischemic stroke. The echocardiographic appearance of a floating thrombus can present multiple differential diagnoses such as myxoma, malignant tumor, or vegetation. The floating aspect may better indicate a thrombus. Only histological analysis can confirm the final diagnosis. A histopathological examination of the removed material from our patient revealed a thrombus.

Currently, there are no definitive guidelines for evaluating and treating patients with this condition [5]. Nevertheless, due to the high risks of sudden death and systemic embolization, prompt surgical removal of the thrombus is recommended as soon as the diagnosis is confirmed [6]. This surgery also provides an opportunity to address the underlying valve disease and potentially treat atrial fibrillation, the main etiological factor, through surgical ablation. The patient underwent thrombus removal and mechanical mitral valve replacement. The evolution was favourable without complications after 3 months of follow-up. Anticoagulation and thombolytic therapy do not appear to have a role in the acute management of left atrial ball thrombus, due to the risk of embolization. However, curative anticoagulation plays a crucial role in preventing recurrence [7]. While there has been a reported successful case of aggressive anticoagulation treating a free-floating left atrial thrombus [2], its effectiveness remains uncertain, and it carries a high risk of embolization, making it a consideration only for high-risk patients. In summary, the presence of a free-floating pinball thrombus poses significant risks of embolism and severe hemodynamic consequences. Surgical removal is promptly recommended in most cases. However, due to the lack of consensus on the optimal treatment approach, decisions are often guided by reported individual cases of this rare and challenging clinical scenario, highlighting the potential contribution of our case to the literature.

Conclusion     

In conclusion, this exceptional case of ischemic stroke characterized by a pinball-like thrombus emphasizes the importance of comprehensive imaging modalities and histological analyses in unraveling the intricate nature of thrombotic events. This case will make a significant contribution to the literature regarding the diagnosis and management of similar cases.

Competing interests     

The authors declare no competing interest.

Authors' contributions     

Hanaa El Ghiati described the case, did the literature search, and wrote the first draft of the manuscript. She also was involved in the echocardiographic study. Houda Mokhliss did a concurrent literature search, reviewed the manuscript and made a substantial contribution. All authors have read and agreed to the final manuscript.

Figures     

Figure 1: apical 4 chambers image showing the left atrial pinball thrombus

Figure 2: apical 2 chamber image of the large thrombus

References