Cardiac conduction abnormalities in endocarditis defined by the Duke criteria

Background Cardiac conduction abnormalities occur in endocarditis and have been associated with infection extension and increased mortality. There hav e been no prospective studies of electrocardiographic (ECG) conduction chan ges in endocarditis. We examined the incidence of ECG changes in a large pr ospective cohort with suspected endocarditis and correlated changes with ec hocardiographic evidence of invasive infection and mortality. Methods One hundred thirty-seven of 1396 (10%) suspected cases of endocardi tis were classified as "definite" or "possible" by the Duke criteria and ha d an interpretable ECG. ECG conduction changes were classified as old (pre- existing hospitalization), new (evident on admission or developed during ho spitalization), or indeterminate. New or indeterminate abnormalities were c onsidered "ECG conduction changes." Echocardiogram results were reviewed to identify infected valves and invasive infection. Results ECG conduction changes were present in 36 of 137 (26%) patients. Pa tients with ECG conduction changes were more often male (69% vs 46%, P =.00 5) and had prosthetic valves (47% vs 23%, P<.001). There were no significan t differences in microbiology results or treatment with cardiac surgery. In 76 (55%) patients, at least one infected valve was identified by echocardi ography; 15 of 76 (20%) patients were determined to have evidence of invasi ve infection. Eight of 15 (53%) invasive infections exhibited ECG conductio n changes compared with 16 of 61 (26%) isolated valve infections (P=.046). Eleven of 36 (31%) patients with ECG conduction changes died during hospita lization compared with 15 of 101 (15%) patients without changes (P=.039). Conclusions ECG conduction changes commonly occur in endocarditis despite m ore sensitive diagnostic criteria and are associated with increased mortali ty and invasive infection.