Infective Endocarditis Vegetation Size vs. Embolic Risk

Study Questions:

Is there an association between vegetation size >10 mm and increased embolic risk among patients with infective endocarditis (IE)?


A literature search of all publications in the PubMed and EMBASE databases from inception to May 1, 2017, was performed with search terms including varying combinations of IE, emboli, vegetation size, pulmonary infarct, stroke, splenic emboli, renal emboli, retinal emboli, and mesenteric emboli. Observational studies or randomized clinical trials that evaluated the association of vegetation size >10 mm with embolic events in adult patients with IE were included; conference abstracts and non–English language literature were excluded. Two reviewers blinded to the other’s work independently extracted data; disputes were resolved by consensus or by a third investigator.


The search yielded 21 unique studies published from 1983 to 2016, with a total of 6,646 unique patients with IE and 5,116 vegetations with available dimensions. Patients with a vegetation size >10 mm had increased odds of embolic events (odds ratio [OR], 2.28; 95% confidence interval [CI], 1.71-3.05; p < 0.001) and mortality (OR, 1.63; 95% CI, 1.13-2.35; p = 0.009) compared with those with a vegetation size <10 mm.


In this meta-analysis of 21 studies, patients with vegetation size >10 mm had significantly increased odds of embolism and mortality. The authors concluded that understanding the risk of embolization will allow clinicians to adequately risk stratify patients and help facilitate discussions regarding surgery in patients with a vegetation size >10 mm.


It makes intuitive sense that larger valvular vegetations may be more prone to embolization, and this meta-analysis supports this. Limitations include presumed selection bias (patients with a vegetation may have been more likely to undergo earlier and/or more aggressive echocardiographic interrogation), treatment of vegetation size as a binary variable, and an unknown effect of antibiotic therapy on embolization. Current (2014) American Heart Association/American College of Cardiology guidelines suggest that intervention may be considered among patients with native valve IE and mobile vegetation(s) >10 mm in length (Class IIb, Level of Evidence B); it is not clear that this meta-analysis should substantially change the weight of that recommendation.

Keywords: Cardiac Surgical Procedures, Diagnostic Imaging, Echocardiography, Embolism, Endocarditis, Endocarditis, Bacterial, Heart Valve Diseases, Risk, Secondary Prevention, Stroke

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