Measurement of vegetations in infective endocarditis: An inaccurate method to decide the therapeutical approach

BACKGROUND

The European Society of Cardiology and American Heart Association guidelines give a central role to the maximal vegetation diameter in the indication for surgery to prevent embolism in left sided infective endocarditis. Vegetation measuring is likely to be inaccurate. The hypothesis herein, is that the vegetation diameter is not an appropriate surgical criterion given the variability of its measurement.

METHODS

Two trained echocardiographers independently measured the maximal vegetation diameter by transesophageal echocardiogram of 76 vegetations in 67 consecutive patients with definite infective endocarditis in an off-line workstation. The interobserver variability was calculated by the interclass correlation coefficient. The relationship between the strength of agreement for the cut-off points of 10 and 15 mm was also calculated. Finally, the number of patients whose surgical indication would have changed depending on which operator measured the vegetation was evaluated.

RESULTS

Interobserver interclass correlation coefficient in the measurement of the maximal longitudinal diameter of the vegetations was 0.757 (0.642-0.839). The strength of agreement of the interobserver analysis for the cut-off point of 10 mm was 0.533 (0.327-0.759). For the cut-off point of 15 mm it was 0.475 (0.270-0.679). If heart failure or uncontrolled infections had been absent, the surgical indication would have changed in a total of 33 patients (33/76; 43%) depending on which operator measured the vegetation.

CONCLUSIONS

The variability in the measurements of the maximal longitudinal diameter by transesophageal echocardiogram is high. Surgical indications based on the cut-off points recommended by the international guidelines should be revised.

Reassessment of vegetation size as a sole indication for surgery in left-sided infective endocarditis

BACKGROUND

Guidelines recommend surgery in left-sided infective endocarditis (LSIE) associated with large vegetations. Given that most patients who undergo surgery also have other indications (heart failure and/or uncontrolled infection), it is not settled whether surgery should be routinely recommended in patients with large vegetations but no other predictors of poor outcome.

METHODS

A total of 726 patients with definitive LSIE were included in our analysis. Mean age was 64.9 years, 61% were male. Multivariate analysis of all patients was performed to determine if vegetation size is related to death in LSIE. Then, patients were divided in two groups according to vegetation size: Group A (>10 mm, n=420) and group B (≤10 mm, n=306). Univariate and multivariate analyses of group A patients were carried out to identify the variables related to death in this group. Impact of surgery on mortality of group A patients without heart failure or uncontrolled local infection (n=139) was assessed.

RESULTS

Age, Staphylococcus aureus, perivalvular complications, heart failure, kidney failure and septic shock, but not vegetation size, were associated with death. Patients with large vegetations showed increased mortality (31.7% in group A vs 24.8% in group B, p=0.045). Group A had more valve rupture and valve regurgitation than group B, but heart failure (55% vs 53%, p=0.678), stroke (22% vs 17.0%, p=0.091), systemic embolism (39% vs 32%, p=0.074), perivalvular complication (28% vs 28%, p=0.865) or septic shock (15% vs 13%, p=0.288) were similar in both groups. In patients from group A without heart failure or uncontrolled infection mortality was similar with and without surgery (n=139; n=70 with surgery, n=69 without surgery; mortality 18.6% vs 11.6% respectively, p=0.251).

CONCLUSIONS

large vegetations identify patients with poor outcome in LSIE. However, surgery is not associated with a better prognosis in patients with large vegetations if they do not present with another predictor of poor outcome such as heart failure or uncontrolled infection. These findings challenge whether vegetation size alone should be an indication for surgery in LSIE.

Effect of the Lysin Exebacase on Cardiac Vegetation Progression in a Rabbit Model of Methicillin-Resistant Staphylococcus aureus Endocarditis as Determined by Echocardiography

Methicillin-resistant Staphylococcus aureus (MRSA) poses significant therapeutic challenges related to its frequency in clinical infections, innate virulence properties, and propensity for multiantibiotic resistance. MRSA is among the most common causes of endovascular infections, including infective endocarditis (IE). Our objective was to employ transthoracic echocardiography (TTE) to evaluate the effect of exebacase, a novel direct lytic agent, in experimental aortic valve MRSA IE. TTE was utilized to evaluate the in vivo effect of exebacase on MRSA-infected vegetation progression when combined with daptomycin (versus daptomycin alone). Primary intravegetation outcomes were maximum size, weights at sacrifice, and MRSA counts at infection baseline versus after 4 days of daptomycin treatment (alone or in addition to exebacase administered once on treatment day 1). A single dose of exebacase in addition to daptomycin cleared significantly more intravegetation MRSA than daptomycin alone. This was associated with a statistical trend toward reduced maximum vegetation size in the exebacase plus daptomycin versus the daptomycin alone therapy groups (P = 0.07). Also, mean vegetation weights in the exebacase-treated group were significantly lower than those of the daptomycin alone group (P < 0.0001). Maximum vegetation size by TTE correlated with vegetation weight (P = 0.005). In addition, intravegetation MRSA counts in the combination group were significantly lower than those of untreated controls (P < 0.0001) and the daptomycin alone group (P < 0.0001). This study suggests that exebacase has a salutary impact on MRSA-infected vegetation progression when combined with daptomycin, especially in terms of vegetation MRSA burden, size, and weight. Moreover, TTE appears to be an efficient noninvasive tool to assess therapeutic efficacies in experimental MRSA IE.

Effect of antibiotic treatment on vegetation size and complication rate in infective endocarditis

BACKGROUND

Infective endocarditis is associated with significant morbidity and mortality, with valvular destruction, and with congestive heart failure. Embolic events are more common in patients with echocardiographically discernible vegetations, especially when vegetations are > 10 mm in diameter.

HYPOTHESIS

The objective of the study was to follow vegetation morphology during native valve endocarditis, to compare it with the clinical course and antibiotic treatment chosen, and to evaluate whether the impact on vegetation size and complication rate of antibiotic regimens differed in patients with positive and negative blood cultures.

METHODS

The effect of different antibiotic regimes on vegetation size monitored by using transesophageal echocardiography was evaluated in 183 patients with echocardiographic evidence of infective endocarditis. A total of 223 vegetations attached to the aortic or mitral valves were detected using the transesophageal approach. The patients were followed for a mean of 76 weeks and underwent a minimum of two consecutive transesophageal echocardiographic examinations.

RESULTS

Treatment with different kinds of antibiotics corresponded with significant differences in vegetation size; vancomycin-associated treatment was related to a 45% reduction, ampicillin to a 19% reduction, penicillin to a 5% reduction, penicillase-resistant drugs to a 15% increase, and cephalosporin to a 40% increase in vegetation size. Multivariate analysis showed that penicillin, cephalosporin, and penicillase-resistant drug treatments were associated with an increased embolic risk, vancomycin treatment with abscess formation, and cephalosporin medication with increased mortality. Plotting changes in vegetation size against the incidence of embolism and mortality, linear regression analysis suggested a 40-50% reduction in vegetation size, thereby greatly reducing the risk of embolism and mortality.

CONCLUSION

Our study shows that different antibiotics have different effects on vegetation size. The highest complication rate was observed when vegetations significantly increased in size during antibiotic treatment. Especially in culture-negative patients, monitoring vegetation size by means of transesophageal echocardiography may prove to be useful for estimating the efficacy of antibiotic treatment.