**4. Discussions**

The prediction of individual patient risk for embolization has proven extremely difficult. Many studies have attempted to use echocardiography to identify a high-risk subset of IE patients who might benefit from early surgery to avoid embolization [5, 6, 8–16]. In several studies using TTE was shown a trend toward higher embolic rates with VEG more than 1 cm in diameter located on the left heart [6]. In our study, the VEG dimension associated with a higher EE rate was about 15 mm probably because of a more precise measurement by TEE. Regarding the VEG diameter, in another study based on TEE, mitral VEG diameter more than 1 cm was associated with the highest incidence of embolism [6]. The association was strengthened when analysis was limited to those patients who had not yet experienced a clinical EE. Among such patients, the predictive accuracy for embolism with large mitral VEG was nearly 100% and in our study that value was about 94%. Mugge et al. had found particularly for patients with mitral valve IE, a VEG diameter greater than 10 mm was highly sensitive in identifying patients at risk for EE. On the other hand, VEG size was not significantly different in patients with and without severe heart failure or in patients surviving or dying during acute IE. In addition, no significant correlation was found between VEG size and IE location or type of infective organism. VEG with a maximal diameter of >10 mm were associated with a 50% incidence of EE, compared with a 42% incidence of emboli in patients with VEG measuring less or equal to 10 mm. Inter observer variability was higher with respect to vegetation shape, mobility, and attachment characteristics. Echocardiographic VEG characteristics were not helpful in defining the risk of embolic complications in patients with IE [5].

Heinle et al. found that patients with a maximum VEG diameter > 10 mm had a significantly higher incidence of EE than those with < or = 10 mm (p < 0.05). There were no significant differences in the frequency of emergent valve replacement between patients with aortic value and mitral valve IE. The maximum size and total score reflecting mobility, extent and consistency of VEG using two-dimensional echocardiography provide useful information to predict the occurrence of EE in patients with IE [6].

Another prospective TEE study, however, found no clear correlation of VEG size with embolization, and transthoracic and TEE characteristics of VEG were not helpful in defining embolic risk in patients with IE [8].

De Castro used multivariate analysis and identified echocardiographic accessible risk factors for subsequent embolism a VEG size of more than 10 mm and mitral valve involvement [8]. Risk factors associated with in-hospital increased mortality rate were embolism, a vegetation size of more than 10 mm, and *Staphylococcus aureus* IE. Also, precise echocardiographic visualization of VEG helps to stratify patients into a high-risk sub-group, needing early prophylactic surgical intervention.

Overall, these data are compatible with previous observations that in general, mitral VEG, regardless their size, are associated with higher rates of embolization (25%) than aortic VEG (10%) [10]. On the other hand, the highest embolic rate (37%) has been seen in the subset of patients with mitral VEG attached to the anterior rather than the posterior mitral leaflet. In particular, mobile VEG attached to the mitral valve with a maximal diameter > 10 mm may be prone to EE [10]. In a retrospective study, Deprele et al. analyzed the risk factors for systemic emboli in IE [13]. They found that the risk of emboli was 57% when the VEG measured >10 mm and only 22% when it was <10 mm (p = 0.003). The mobility of the VEG was also a risk factor: 48% if the vegetation was mobile; and 9% if fixed (p = 0.003). Sex, age, pathogen, antibiotic treatment, type of valve and the number and position of the VEG were not found to be risk factors. With multivariate analysis, only mobility was identified as a risk factor.

**4. Discussions**

treatment has been started.

78 Advanced Concepts in Endocarditis

The prediction of individual patient risk for embolization has proven extremely difficult. Many studies have attempted to use echocardiography to identify a high-risk subset of IE patients who might benefit from early surgery to avoid embolization [5, 6, 8–16]. In several studies using TTE was shown a trend toward higher embolic rates with VEG more than 1 cm in diameter located on the left heart [6]. In our study, the VEG dimension associated with a higher EE rate was about 15 mm probably because of a more precise measurement by TEE. Regarding the VEG diameter, in another study based on TEE, mitral VEG diameter more than 1 cm was associated with the highest incidence of embolism [6]. The association was strengthened when analysis was limited to those patients who had not yet experienced a clinical EE. Among such patients, the predictive accuracy for embolism with large mitral VEG was nearly 100% and in our study that value was about 94%. Mugge et al. had found particularly for patients with mitral valve IE, a VEG diameter greater than 10 mm was highly sensitive in identifying patients at risk for EE. On the other hand, VEG size was not significantly different in patients with and without severe heart failure

**Figure 5.** Correlation between clinical and echo parameters and the appearance of the embolic events after the antibiotic

The effect of VEG size on embolic potential was specific to the infecting organism, with large VEG independently predicting EE only in the setting of streptococcal IE [13, 17–19]. In contrast, staphylococcal or fungal IE appears to carry a high risk of embolization that is independent of the VEG size.

The evolution of VEG size revealed by TEE appears to predict EE; however an increase in VEG size revealed by TEE over 4–8 weeks of antibiotic therapy. In patients with IE and increasing VEG size, the EE rate among was twice that of patients with static or decreasing VEG size. In addition, a second peak of late EE occurred at 15–30 weeks after diagnosis of IE, and it was associated with failure of a VEG to stabilize or diminish in size as defined by echocardiography [5, 6].

**References**

[1] Bayer AS. Infective endocarditis. Clinical Infectious Diseases. 1993;**17**:313-320

New York, NY: Raven Press; 1991. pp. 515-559

Annals of Internal Medicine. 1991;**114**:635-640

American Journal of Medicine. 1994;**96**:200-209

North America. 1985;**69**:385-398

1989 Sep;**14**(3):631-638

1994;**74**(8):799-801

[2] Francioli P. Central nervous system complications of infective endocarditis. In: Scheld WM, Whiteley RJ, Durack DT, editors. Infections of the Central Nervous System.

Prediction of Embolic Events in Infective Endocarditis Using Echocardiography

http://dx.doi.org/10.5772/intechopen.76845

81

[3] Lerner P. Neurologic complications of infective endocarditis. The Medical Clinics of

[4] Steckelberg JM, Murphy JG, Ballard D, Bailey K, Tajik AJ, Taliercio CP, Giuliani ER, Wilson WR. Emboli in infective endocarditis: The prognostic value of echocardiography.

[5] Mugge A, Daniel WG, Frank G, Lichtlen PR. Echocardiography in infective endocarditis: Reassessment of prognostic implications of vegetation size determined by the transthoracic and the transesophageal approach. Journal of the American College of Cardiology.

[6] Heinle S, Wilderman N, Harrison JK, Waugh R, Bashore T, Nicely LM, Durack D, Kisslo J. Value of transthoracic echocardiography in predicting embolic events in active infective endocarditis. Duke Endocarditis Service. American Journal of Cardiology.

[7] Durack DT, Lukes AS, Bright DK. New criteria for diagnosis of infective endocarditis: Utilization of specific echocardiographic findings. Duke Endocarditis Service. The

[8] Koie S, Iwase M, Hasegawa K, Matsuyama H, Yamamoto H, Takeda K, Kato C, Kimura M, Hishida H, Kamiya H, Ohno M. Echocardiographic prediction of risk for embolism in patients with infective endocarditis. Journal of Cardiology. 1997;**29**(Suppl 2):117-122

[9] De Castro S, Magni G, Beni S, Cartoni D, Fiorelli M, Venditti M, Schwartz SL, Fedele F, Pandian NG. Role of transthoracic and transesophageal echocardiography in predicting embolic events in patients with active infective endocarditis involving native cardiac

[10] Rohmann S, Erbel R, Gorge G, Makowski T, Mohr-Kahaly S, Nixdorff U, Drexler M, Meyer J. Clinical relevance of vegetation localization by transoesophageal echocardiog-

[11] Mugge A, Daniel WG. Echocardiographic assessment of vegetations in patients with infective endocarditis: Prognostic implications. Echocardiography. 1995;**12**(6):651-661

[12] Daniel WG, Mugge A, Grote J, Hausmann D, Nikutta P, Laas J, Lichtlen PR, Martin RP. Comparison of transthoracic and transesophageal echocardiography for detection of abnormalities of prosthetic and bioprosthetic valves in the mitral and aortic positions.

raphy in infective endocarditis. European Heart Journal. 1992;**13**(4):446-452

valves. The American Journal of Cardiology. 1997;**80**(8):1030-1034

The American Journal of Cardiology. 1993;**71**:210-215

Because of the known decrease in embolic risk over the first 2 weeks of antibiotic therapy, the benefit of surgery in avoiding catastrophic embolic events is the greatest early in the course of the IE. Early surgical intervention may preclude a primary or recurrent major EE but exposes the patient to both the immediate and the life-long risks of valve replacement. That is why, the strategy for surgical intervention to avoid systemic embolization in IE still remains specific to the individual patient, benefit being the greatest in the early phase of IE when embolic rates are the highest and when other predictors of a complicated course are present (i.e., recurrent embolization, congestive heart failure aggressive, antibiotic-resistant organisms or prostheticvalve IE). Surgical options must be considered when large VEG are detected on the mitral valve, particularly the anterior leaflet. Failure of a VEG to stabilize or diminish in size on TEE during clinically adequate therapy may also predict later EE.
