Periannular Extension of Infection Extension of IE beyond the valve annulus predicts a higher mortality rate, more frequent development of heart fail- ure, and more frequent need for cardiac surgery.284,297,298 Perivalvular cavities form when annular infections break through and spread into contiguous tissue. In aortic NVE, this generally occurs through the weakest portion of the annulus, which is near the membranous septum and atrio- The anatomic vulnerability of this area explains both why abscesses occur in this location and why heart block is a frequent sequela.300 Periannular exten- sion is common, occurring in 10% to 40% of all NVE and complicating aortic IE more commonly than mitral or tri- Periannular infection is of even greater con- cern with PVE, occurring in 56% to 100% of patients.298,302 Perivalvular abscesses are particularly common with pros- thetic valves because the annulus, rather than the leaflet, is the usual primary site of infection, especially in early PVE and on bioprosthetic valves.302 Under the influence of systemic intravascular pressures, abscesses may progress to fistulous tracts that create intracar- diac or pericardial shunts. The mortality rate was 41% in a of patients with aorto-cavitary fistulization despite surgical intervention in 87%. Multivariate analysis demon- strated that factors associated with an increased risk of death included moderate to severe heart failure, PVE, and urgent or emergency surgical intervention. In some cases, progressive periannular infection totally disrupts the ventricular-aortic continuity or the mitral-aortic trigone. Such structural lesions and intracardiac fistulas may be catastrophic; even if their hemodynamic impact is tolerated, these lesions will not heal with medical treatment alone and require urgent operative intervention. Clinical parameters for the diagnosis of perivalvular extension of IE are inadequate. 