The mitral valve is most often affected, and valvular regurgitation is the predominant func- tional abnormality seen in APA syndrome with complicating valvular involvement. To complicate matters, the APA syn- drome may develop secondary to IE.239 Numerous other causes of noninfective vegetative endo- carditis can mimic IE. These can be categorized into 4 : neoplasia associated (atrial myxoma, marantic endocarditis, neoplastic disease, and carcinoid), autoimmune associated (rheumatic carditis, systemic lupus erythematosus, polyarteritis nodosa, and Beh et disease), postvalvular surgery (thrombus, stitch, or other postsurgery changes), and miscel- laneous (eosinophilic heart disease, ruptured mitral chordae, and myxomatous degeneration). Recommendations 1. An evaluation of epidemiological factors, history of prior infections including cardiovascular infections, exposure to antimicrobials, clinical course, sever- ity, and extracardiac sites of infection of the current infection should be performed in all culture-nega- tive endocarditis cases (Class I; Level of Evidence C). 2. Consultation with an infectious diseases specialist to define the most appropriate choice of therapy in patients with culture-negative endocarditis is rec- ommended (Class I; Level of Evidence C). 3. For patients with acute (days) clinical presentations of native valve infection, coverage for S aureus, -hemolytic streptococci, and aerobic Gram- negative bacilli is reasonable (Class IIa; Level of Evidence C). 4. For patients with a subacute (weeks) presenta- tion of NVE, coverage of S aureus, VGS, HACEK, and enterococci is reasonable (Class IIa; Level of Evidence C). 5. For patients with culture-negative PVE, cover- age for staphylococci, enterococci, and aerobic Gram-negative bacilli is reasonable if onset of symp- toms is within 1 year of prosthetic valve placement (Class IIa; Level of Evidence C). 6. 