RIGHT SIDED ENDOCARDITIS: CASE SERIES FROM MOROCCO

Objective: Compared with the extensive data on left sided infective endocarditis, right-sided infective endocarditis (RSIE) remains a rare condition. It accounts for 5–10% of all cases of infective endocarditis (IE) [1] [2] [3]. Although it is predominantly encountered in the injecting drug user (IDU) population, where HIV and HCV infections often coexist, rheumatic heart disease remains the most important predisposing factor for IE in our context. The aim our study is to report clinical, investigation, management and outcome data in 5 patients diagnosed with RSIE in our department during the last 2 years. Methods: A retrospective analysis of data of 5 patients with right sided endocarditis in a tertiary care center from 2018 to 2020 was

The clinical presentation is often a persistent fever with respiratory symptoms whilst signs of systemic embolization as seen in left-sided IE are notably absent. The diagnosis of IE is made based upon a synthesis of clinical, microbiological, and echocardiographic findings. The modified Duke criteria are the standard criteria used to guide the diagnosis of IE (1). The two major criteria for a definite diagnosis of IE are positive blood cultures and evidence of endocardial vegetations on either a transthoracic (TTE) or transesophageal echocardiogram (TEE). There are also five minor criteria: persistent fever, the risk factors of an invasive procedure within 60 days, a prosthetic valve, current intravenous drug use, and the classic signs of Janeway lesions, Osler's nodes or Roth's spots (vascular and immunologic phenomena). However, many criteria can be missed given the subtle evolution and physiopathology of RSIE.
The prognosis is mainly determined by the early diagnosis and early medical/surgical management to decrease complications and death.
The aim our study is to report clinical, investigation, management and outcome data in 5 patients diagnosed with RSIE in our department during the last 2 years.

Methods:-
All the patients data were recorded in a tertiary care university hospital from 2018 to 2020.
The diagnosis of IE was based on modified Dukes criteria. There was no history of IV drug abuse in any of the patients.
Clinical, microbiological, radiographic investigations, management, and follow-up information were analyzed.

History and clinical presentation :
All of our patients were young aged females; none of them had cardiac devices or history of drug use. Persistent fever was the most common clinical presentation. Interestingly, 4 patients presented clinical heart failure.

Discussion:-
Incidence of RSIE has been described as 5%-10% of IE. However, recently published studies indicate an increased incidence of 10%-20% (4-6). It is often associated with intravenous drug use (IVDU), intracardiac devices, and central venous catheters, all of which have become more prevalent in the western world over the past 20 years (1)

Primary prevention
In our context, very few studies have estimated the prevalence of RSIE; However, rheumatic heart disease remains the most prevalent etiology as the prevalence of this pathology is high in Africa (7-9).
Moreover, IE is also well-recognized complication of ventricular septal defects with an incidence in several large series of approximately 1/1000 patient years. VSD, aortic stenosis, coarctation of the aorta, and patent ductus arteriosus are associated with high-velocity or turbulent flows, and are at a much higher risk for developing infective endocarditis. Conversely, defects such as secundum atrial septal defects are not associated with infective endocarditis. The infective process may involve the margins of the defect or the aortic or tricuspid valve, the principal causative organisms being streptococcus viridans and staphylococcus aureus (10) .
In our case series, one patient had a VSD and another one had an ASD, no evident mode of entry was founded in the two others except recent oral care and poor oral hygiene. Currently, the American Heart Association/American College of Cardiology and the task force of the European Society of Cardiology for IE antibiotic prophylaxis have precluded the need for antibiotics in patients with acyanotic congenital hemodynamically insignificant atrial and ventricular septal defects (11).
As rheumatic heart disease is a major public health problem in our country, it can be interesting to evaluate the interest of antiobiotic prophylaxis in patients with VSDs and ASDs; larger studies in our context (North Africa) need to be carried out.

Feature of valvular envolvement
Another interesting observation in our case series is the existence of isolated pulmonary valve IE in one patient, and the coexistence of pulmonary and tricuspid valve IE in another one. In literature review, isolated pulmonary valve endocarditis is rare. It is assumed that its rarity is due to the low pressure gradients within the right heart, the low prevalence of congenital malformations, the lower oxygen content of venous blood, and the differences in the covering and vascularization of the right heart endothelium (12). Most cases of pulmonary valve endocarditis in children are secondary to the presence of a congenitally abnormal pulmonary valve and in adults secondary to intravenous drug abuse. Isolated pulmonary valve endocarditis has also been identified in patients undergoing chronic hemodialysis and orthotopic liver transplantation (13,14). A significant number of patients present with primarily pulmonary symptoms such as pleuritic chest pain, cough, and dyspnea. When peripheral embolic or neurologic features occur, either left-sided endocarditis or paradoxical embolism should be considered.
The clinical presentation of isolated pulmonary valve endocarditis in one patient included persistant fever, and in the other one features of multiple septic pulmonary embolism, and a new pulmonary murmur. A review of the published data indicated that the role of surgery in isolated pulmonic valve endocarditis is unclear. Recurrent pulmonary emboli are not an indication for surgery, which is only needed if fever persists despite 3 weeks of appropriate antibiotic treatment in the absence of a pulmonary abscess (15). Surgical options include debridement of the infected area, vegetation excision with either valve preservation or valve repair or valve replacement. Preservation of the native pulmonary valve is recommended whenever possible, and use of a homograft or xenograft is preferred if replacement is unavoidable, which was performed in our patient with isolated pulmonary IE.

Micro-organisms and antibiotic therapy features:
The typical microorganisms causing right sided IE are listed in Table 5. Staphylococcus aureus is the predominant organism (60-90% of cases) in rightsided IE, with a steadily increasing proportion of methicillin resistant Staphylococcus aureus strains and polymicrobial infections (1). Streptococcal and coagulase negative staphylococcal infections are also frequent causes of right sided IE, with S. pneumoniae IE occurring more commonly in the setting of chronic alcoholism, regardless of IVDU. However, S. pneumoniae is still more likely to involve the left side of the heart, with right sided IE accounting for <10% of cases (1). In our context, streptococcus is most likely to be the causative bacterial agent incriminated in RSIE.

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Intravenous antibiotics are the cornerstone of treatment for right-sided IE affecting the TV. However, surgical intervention may be warranted in several situations, as described in Table 6. (1). The proportion of patients who are reported to undergo surgery for right sided IE ranges from 5% to 40% (16). Surgical techniques consist of vegetation removal, radical debridement of vegetations, and infected tissue and valve repair. The use of prosthetic material (ie, valve replacement) should be avoided when possible (17) . Surgical techniques can be also divided into "prosthetic" (tricuspid valve replacement or ring annuloplasty) or "nonprosthetic" (annuloplasty, bicuspidization, vegectomy [solely removing the vegetation], or valvectomy [removal of tricuspid valve leaflet]). For right sided IE associated with IVDU, surgical management should strive to avoid artificial material and focus on vegetation removal and valve repair, which are associated with better late survival (17). In our case series, 4 patients underwent surgical treatment; the indications were the presence of right heart failure secondary to severe tricuspid regurgitation and the size of the vegetations. Unfortunately, one patient died of massive pulmonary embolism despite well conducted antibiotherapy.

Tab 6: Indications for Surgical Interventions for Right-Sided Infective Endocarditis.
The most common complications include valvular insufficiency, abscess formation, and septic pulmonary embolism (18). In a recent review, a mean of 1.6 complications per right-sided IE patient were reported, and the most common complications were valvular insufficiency, embolic events, and abscess formation (19). Pulmonary involvement occurred in 80% of these cases and varied from minor atelectasis to large infiltrates, pleural exudates, and cavitation, generally involving the lower lobes.
Invasive disease, such as the formation of cardiac abscesses, cavities, or pseudo-aneurysms, is rare in right-sided IE (0.7%) and the infection is usually limited to the TV leaflets and does not extend beyond the annulus. In contrast, invasive IE is significantly more common in aortic valve IE (65%) and mitral valve IE (31%). It has been hypothesized that the development of cardiac abscesses, cavities, or pseudoaneurysms requires high intracavitary pressures and thus almost never occur in the low pressure right sided chambers (20).

Conclusion:-
RSIE is rare and occurs in a wide range of underlying conditions like implantable electronic devices, indwelling catheters, CHD and immunocompromised state. Surprisingly, it can occur in young individuals without known risk factors. In our context, rheumatic heart disease remains the most incriminated etiology which lead us to question three essential points: 1. The interest of antibiotic prophylaxis in young patients with VSDs 2. The use of empiric antibiotics with action against streptococcus