[Clinical, echocardiographic and prognostic profile of Streptococcus viridans left-sided endocarditis]

Published case series on Streptococcus viridans endocarditis are scarce and outdated. The aims of our study were multiple: to analyze the profile of the Streptococcus viridans endocarditis, to compare it with other types of left-sided endocarditis and with cases caused by Staphylococcus aureus, and to determine predictors of poor outcome in Streptococcus viridans endocarditis.

We analyzed 441 episodes of endocarditis: 330 left-sided and 54 caused by Streptococcus viridans (16%). We compared the 54 cases due to Streptococcus viridans with the remaining cases of left-sided endocarditis in our series, and also with cases caused by Staphylococcus aureus. We also analyzed the predictors of death and urgent surgery in Streptococcus viridans endocarditis.

Left-sided endocarditis due to Streptococcus viridans led to a similar degree of valvular destruction, showed acute onset less frequently, and led to less renal failure, septic shock and mortality than the remaining cases of left-sided endocarditis in our series. The same differences were found in comparison to Streptococcus viridans endocarditis. Prognostic factors for Streptococcus viridans left-sided endocarditis were heart failure and periannular complications.

Although Streptococcus viridans is a nonaggressive microorganism, valvular destruction is similar to that caused by other pathogens when it causes left-sided endocarditis. Nonetheless its prognosis is better, a feature which may be related to the fact that the systemic infectious syndrome can be treated more effectively. Prognostic factors in left-sided endocarditis due to Streptococcus viridans are heart failure and periannular complications.