Mitral Valve Endocarditis in a Pediatric Patient: When Is the Right Time to Intervene? A Case Report

Abstract

Infective endocarditis (IE) is most often treated conservatively with medical management. There are no clear guidelines in the pediatric population for timing of surgical intervention. This is a case report of an 18-month-old male admitted to the hospital with IE. His workup showed a large vegetation on the mitral valve with evolving regurgitation caused by Kingella kingae, a HACEK group organism. Factors that led to consideration for early surgical intervention included the size of the vegetation (19 mm), the etiologic agent (K. kingae) described to be associated with a high rate of complications, the absence of neurologic complications, and the possibility for valve-sparing repair strategies. Following mitral valve repair, the patient made an uneventful recovery and he was discharged home within a week, to complete a course of antibiotics. Surgical intervention early in the disease course of IE can be a safe option and could pre-empt the development of embolic complications especially in the setting of very large vegetations and certain types of high-risk organisms. Additionally, early surgery allows for valve repair and could avoid valve replacement with its attendant risk of anticoagulation therapy and future surgery.

Introduction

Infective endocarditis (IE) is usually treated conservatively with medical management. In the pediatric population, there are no clear guidelines for when it might be appropriate to operate on the affected valve.

This report describes the clinical course and management of a child with mitral valve endocarditis, and a discussion of relevant considerations that aid in making the decision for timely surgical intervention.

Case Presentation

An 18-month-old boy with no known risk factors for IE presented with a week’s history of fever, rash, and fussiness. Physical exam showed an afebrile, well-appearing child with normal vital signs and a normal baseline neurologic exam. A holosystolic murmur was present. Electrocardiogram and chest radiograph were normal. Labs showed mild leukocytosis and mild thrombocytopenia.

Initial echocardiogram revealed a large (14 mm × 19 mm) mobile vegetation on the atrial side of the posterior leaflet of the mitral valve with moderate mitral regurgitation (MR) and normal systolic function (Figs. 1, 2, and 3). Two sets of blood cultures grew gram-negative bacilli that speciated as Kingella kingae. After 72 h of antibiotic treatment, subsequent blood cultures remained negative. Evaluation for septic emboli was negative with a normal non-contrast computerized tomography scan of the brain, renal sonogram, and ophthalmologic exam.

Fig. 1
figure1

Parasternal long axis view, demonstrating large vegetation on the posterior mitral valve leaflet

Fig. 2
figure2

Parasternal short axis view of the mitral valve showing large vegetation on the posterior leaflet

Fig. 3
figure3

Color Doppler in apical 4-view (A4C) view demonstrating moderate mitral regurgitation

Repeat echocardiogram at 1 week showed persistently large vegetation with worsening MR, mild inflow gradient of 5 mmHg, and prolapse of the mass into the LV during diastole (Fig. 4). The large vegetation size and worsening valve regurgitation on echocardiogram and the high-risk causative organism prompted early surgical intervention.

Fig. 4
figure4

A4C view demonstrating large vegetation prolapsing in the left ventricle during diastole

Using cardiopulmonary bypass and cardioplegic arrest, a valve-sparing repair was undertaken. The vegetation was excised, and autologous pericardium was used to patch augment the posterior leaflet. The child made an excellent recovery with no neurologic sequelae and was discharged home within a week to complete the remainder of his 4-week antibiotic course. Echocardiogram at discharge and follow-up visit 7 months postoperatively showed a durable repair with trivial to mild MR, good leaflet excursion, and normal function (Fig. 5).

Fig. 5
figure5

A4C view 7 months post-op with and without Doppler, showing excellent repair with normal leaflet excursion and trivial MR

Discussion

Currently, pediatric recommendations for surgery in native mitral valve endocarditis are derived from guidelines for adults. Surgical intervention, usually required in approximately 20% of pediatric patients with IE, is indicated when there is an increased risk of stroke, hemodynamic compromise, or failure of antibiotic therapy [1]. In general, left-sided IE tends to carry a higher mortality than right-sided IE [2].

Although there are clear indications for surgery in adults, based on the guidelines provided by the 2009 European Society of Cardiology (heart failure, uncontrolled infection, and prevention of embolism) and the 2014 American College of Cardiology–American Heart Association (valve dysfunction causing heart failure, antibiotic resistant organism, heart block, abscess, and persistent infection), the optimal timing in the absence of such indications, and especially in pediatric patients, can often be a complicated clinical decision [3, 4].

In favor of early surgery, which was variably defined as intervention within a week or two of diagnosis or during the same hospital admission and prior to the completion of a full 6-week course of antibiotics, a recent meta-analysis of 16 cohort studies with over 8000 adult patients concluded that early surgery in IE significantly lowers the incidence of in-hospital mortality and long-term mortality as compared with the non-early surgery group [5]. This is further corroborated in a recent series where the duration of preoperative antibiotic treatment was shown to be significantly correlated with increased mortality [1]. In this study, the authors demonstrated that new embolic phenomena occurred at a mean time of 3.2 days following diagnosis of IE and showed that there is no increased risk of mortality or re-operation when surgery was performed during the active phase of IE.

The risk attributed to early surgical intervention must be balanced against the risk of death and the sequelae of embolic phenomena or valve destruction. The extent and the location of vegetations influence these latter risks considerably. While vegetation size > 15 mm is a known risk factor for death in adults, Khoo et al. showed that vegetation size relative to patient body surface area, rather than its absolute size, was a significant independent predictor of early mortality, especially in children with left-sided lesions [1]. A 1-mm/m2 increase in vegetation size-body surface area ratio increased the relative risk of mortality by 7%.

While our patient’s vegetation size of 14 mm × 19 mm clearly placed him at a high risk for embolic complications, there was an additional and equally grave risk posed by its potential to destroy the valve.

Valve destruction and loss of leaflet surface area due to vegetations have serious implications, especially in the pediatric patient in that it could preclude valve preservation. In the series from Texas, 50% of surgical patients with native valve involvement were seen to require valve replacement [6]. In children, a mechanical mitral valve entails life-long anticoagulation which is risky in its own right and almost certainly places them at risk for future valve re-replacement. Therefore, an approach that allows for a valve-sparing repair strategy, aimed at reducing this chronic medical burden and its subsequent impact on quality of life, deserved serious consideration.

Apart from vegetation size and the consequent risks related to embolism and valve destruction, it is worth noting that the causative organism may be an important consideration as well. Kingella kingae is increasingly recognized as an invasive pathogen in children under 3 years of age, with IE as its most severe manifestation. Involvement of a native valve with this organism carries a 31% rate of neurologic complications and a 10% mortality rate [7]. The consequences of medical management or delayed surgical intervention in this instance is therefore not without serious risk.

This patient had several factors that needed to be weighed carefully in deciding the timing of surgical intervention. Although there was no evidence of ventricular dysfunction or heart failure, the importance of valve preservation in a child, the high-risk profile of the causative organism, and the risk for embolism and its sequelae were all considerations that were relevant to the decision, beyond those provided by consensus guidelines alone. This report highlights the specific factors that were taken into consideration in deciding optimal timing of surgery in a pediatric patient with mitral valve endocarditis that may allow for a positive outcome.

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Correspondence to Sujata Subramanian.

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O’Brien, D.R., Albaro, C.A. & Subramanian, S. Mitral Valve Endocarditis in a Pediatric Patient: When Is the Right Time to Intervene? A Case Report. SN Compr. Clin. Med. 2, 829–832 (2020). https://doi.org/10.1007/s42399-020-00308-x

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Keywords

  • Infective endocarditis
  • Vegetation
  • HACEK group
  • Valve-sparing surgery