Clinical Characteristics, Treatment, and Outcomes of Children with Severe Mycoplasma Pneumonia Complicated with Cardiac Thrombosis: A retrospective study

Objective: To explore the clinical characteristics, treatment, and outcomes of children with severe mycoplasma pneumonia (SMPP) complicated with cardiac thrombosis. Methods: Clinical data of 16 children with SMPP complicated with cardiac thrombosis, who were treated at three medical centers in China from July 2018 to April 2025, were retrospectively analyzed. Results: Among the 16 children, 11 were males and 5 were females, with an age of onset of 8.03 ± 2.17 years. All 16 children presented with fever and cough, while additional symptoms included dyspnea in 8 cases, chest pain in 7 cases, hemoptysis in 3 cases, and chest tightness in 1 case. A total of 15 children underwent testing for the Mycoplasma pneumoniae drug resistance genes 2063A>G and 2064A>G, of which 14 tested positive. The plasma D‑dimer levels of 16 children were 9.18 (6.57, 15.91) mg/L, all of which were higher than normal. Among the 16 children, 5 had decreased activity of anticoagulant proteins (protein C, protein S, antithrombin Ⅲ), and 8 tested positive for antiphospholipid antibodies. Chest CT scans of all 16 children showed pulmonary consolidation and (or) atelectasis, with pleural effusion present in 12 cases. In the 16 children, thrombosis was detected at 14.0(11.25, 17.25) days after the onset of illness. The locations of cardiac thrombosis included the right ventricle in 10 cases, the right atrium in 5 cases, and the left atrium in 1 case.Additionally, 11 cases had pulmonary vascular embolism, comprising 10 cases of pulmonary artery thrombosis and 1 case of pulmonary vein thrombosis. After anticoagulant treatment, cardiac thrombi disappeared in 11children. Five children who did not show improvement with anticoagulation underwent surgical thrombectomy. In the follow‑up of 16 children, lung imaging basically returned to normal, with no major hemorrhagic events or other adverse events. Conclusion: An early and thorough cardiac ultrasound examination should be performed in children with SMPP who present with chest pain, hemoptysis, significantly elevated D-dimer levels, pulmonary consolidation, atelectasis, and pericardial effusion. SMPP complicated by cardiac thrombosis, prognosis is good following anticoagulation or surgical treatment.