Background <p>Cardiac hydatid cysts are rare, even in endemic regions, and are typically asymptomatic. Systemic embolism resulting from rupture of a cardiac hydatid cyst is exceptionally uncommon, and thrombosis within a cyst has not previously been reported.</p> Case presentation <p>We describe the case of a 7-year-old girl who presented with left hemiplegia and aphasia secondary to an ischemic stroke. Neuroimaging revealed a right middle cerebral artery infarction, while cardiac imaging identified a heterogeneous mass at the apex of the left ventricle. Further investigations confirmed a ruptured and partially thrombosed hydatid cyst. Additional infarctions in the spleen and kidneys supported a diagnosis of systemic embolization.</p> <p>Surgical management was performed via a left pleural approach due to pericardial adhesions. Cardiopulmonary bypass was established, and aortic cross-clamping was used to prevent embolization. A pre-declamping transverse aortotomy revealed and allowed removal of the germinative membrane. The patient recovered well postoperatively, with resolution of aphasia but persistent hemiplegia. Histopathology confirmed hydatid disease.</p> Conclusion <p>This case represents the first reported instance of a ruptured and thrombosed cardiac hydatid cyst causing systemic embolization. It underscores the critical role of intraoperative aortic inspection before declamping to prevent secondary embolic events.</p>