Analysis of Clinical Features and Outcomes of Infective Endocarditis with Very Large Vegetations: A Retrospective Observational Study from 2016 to 2022

Background: Cases of infective endocarditis (IE) with > 30 mm vegetations are rare and are associated with high mortality. Clinical experience, clear therapeutic standards, and outcome evidence about these cases are still lacking. Methods: Detailed clinical data from patients suffering from IE complicated with > 30 mm vegetations were collected from a hospital medical record system. Age-and sex -matched IE cases with 10-20 mm vegetations were used as a control group. Results: Twenty-two patients with > 30 mm IE vegetations confirmed by biopsy and transthoracic echocardiography (TTE) were included. Thirteen (59.0%) patients had basic cardiac diseases, mainly congenital heart disease (CHD), rheumatic heart disease, and device-related issues. Fever (81.8%), heart murmur (86.4%), heart failure (86.4%), and embolism (50.0%) were common clinical manifestations and complications. TTE showed the diameter of vegetations was 34.5 (30.0-39.8) mm. The vegetations were usually accompanied by severe valvular regurgitation and pulmonary hypertension, and were most often located in the mitral valve (38.4%). Laboratory examinations indicated anemia, hypoalbuminemia, heart failure and inflammation. The rate of positive blood culture was 68.2%. Streptococcus viridans was the most frequent pathogen (26.7%). All individuals underwent vegetectomy and valve replacement or repair surgery, within 2 days of diagnosis. Compared with 10-20 mm vegetations group, > 30 mm vegetations group had more complicated basic cardiac diseases, more special microbial infection, higher levels of procalcitonin (PCT) and D-dimer, more common heart failure and embolism. They received more biological valve replacements, and had longer intensive care unit length of stay (ICU-LOS). A few patients developed significant postoperative adverse events, including intracerebral hemorrhage (ICH), septic shock, and new symptomatic thrombosis. Re-exploratory thoracotomy was performed in two cases. All patients survived during 6-month follow-up without IE recurrence in > 30 mm vegetations group, while there was one death and one recurrence in the 10-20 mm vegetations group. Conclusions: For IE complicated with > 30 mm vegetations, clinical characteristics are diverse and vegetations on TTE are prone to misdiagnosis as thrombus or tumors. This article also emphasizes the use of > 30 mm IE vegetations as an independent indication for early surgery to improve prognosis.