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factor,133,723 while patients with indwelling vascular catheters have the worst prognosis.725 IE of transcatheter pulmonary valves is covered in Section 12.2, whereas CIED-related right-sided IE is covered in Section 12.3. The most common microorganism causing right-sided IE is S. aureus, accounting for the majority of patients.723,726 The tricuspid valve is much more commonly infected than the pulmonary valve in patients with right-sided IE.723,727 Right-sided IE may also involve non-functional embryonic remnants of the right atrium (e.g. Eustachian valve).723,727 Right-sided IE rarely spreads to involve the left-sided cardiac structures, whereas spread from left- to right-sided structures is not uncommon.728

12.6.1 Diagnosis and complications

Right-sided IE patients present with fever, bacteraemia, and pulmonary complaints (i.e. cough, chest pain, or haemoptysis). Right-sided HF may also occur due to tricuspid or pulmonary regurgitation, or to pulmonary hypertension induced by multiple pulmonary septic emboli.133 Diagnosis is most frequently confirmed by echocardiographic findings of vegetations on the tricuspid valve or, less frequently, pulmonary valve. Adequate evaluation of the tricuspid valve may be performed with TTE, due to the anterior location of the valve and the large vegetations frequently observed in right-sided IE. Transoesophageal echocardiography is frequently required, however, particularly for evaluation of the pulmonary valve or in patients with indwelling venous catheters or intracardiac devices.729 Intracardiac echocardiography may also be helpful in select patients. Vegetations may be challenging to identify on the pulmonary valve even with TOE, especially in patients with a prosthetic valve in the pulmonary position. [18]FDG-PET imaging may be very helpful in such patients.34,730 Perivalvular abscess formation and invasion into surrounding structures is rarely seen in right-sided IE, unless it is a secondary consequence of left-sided IE.728 CT is useful in order to identify concomitant pulmonary disease, including infarcts and abscess formation.

12.6.2 Endocarditis in people who inject drugs

Infective endocarditis in PWID is an increasing global phenomenon.10,132,133,141 Repeat i.v. injections result in contaminated particles that reach the tricuspid valve and right-heart chambers and can also lead to infection of left-heart structures, which is associated with worse prognosis.614 PWID patients also have an increased rate of human immunodeficiency virus (HIV) and hepatitis than other patients with right-sided IE.731 The majority of right-sided IE in PWID can be treated successfully with antibiotic therapy. Mortality rates of PWID are relatively low, even when surgery is required, probably due to the young patient age.723 However, PWID have a markedly increased rate of IE recurrence, particularly in the first 6 months post-surgery.133,614,723,732

12.6.3 Prognosis and treatment

Right-sided IE is generally a more benign clinical entity than left-sided IE and can be medically managed in ∼90% of patients, with surgery reserved for those who fail medical therapy.733 Patients with CIED-related right-sided IE have a worse prognosis as compared with non-CIED-related right-sided IE (see Section 12.4).723 725 Right-sided IE in immunocompromised patients, particularly fungal infections, carries a very poor prognosis.

12.6.3.1 Antimicrobial therapy

S. aureus and CoNS are the cause of right-sided IE in a large proportion of cases, with S. aureus predominating in PWID and CoNS being more common in patients with indwelling devices.723,726 MRSA rates may be increasing over time, particularly in PWID.133 Right-sided IE due to Streptococcus spp. is unusual but can be observed in alcoholics and diabetics. P. aeruginosa and other Gram-negative organisms are rare causes of right-sided IE, while Candida albicans is mostly seen in immunocompromised patients.

Empirical antimicrobial therapy depends on the suspected microorganism, the type of drug and solvent used by the PWID, and the infection location,734 but S. aureus must be initially covered in all cases. Initial treatment consists of penicillinase-resistant penicillin, vancomycin, or daptomycin, depending on the local prevalence of MRSA,735 in combination with gentamicin. If the patient is a pentazocine addict, an anti-Pseudomonas agent may also be required, as the use of recreational drugs may also entail infections with Gram-negative bacteria.735 Very large vegetations and history of brown heroin use dissolved in lemon juice suggest infection for Candida spp. (not C. albicans), and therefore antifungal treatment should be added.736 Antifungals may be necessary in selected PWID, particularly if immunocompromised.737 Once the causative organisms have been isolated, therapy has to be adjusted. An RCT demonstrated that a 2-week treatment course may be sufficient and that aminoglycosides may be unnecessary.738 717 Two-week treatment with oxacillin (or cloxacillin) without gentamicin is effective when: (i) MSSA is the causative organism; (ii) There is good clinical and microbiological response to treatment

(>96 h);739 (iii) The vegetation size is ≤20 mm; and (iv) There is an absence of metastatic sites of infection or empyema

and cardiac or extracardiac complications,739,740 prosthetic valve or left-sided valve infection,741 and severe immunosuppression.742

Glycopeptides (vancomycin) should not be used in a 2-week treatment. The standard 4–6-week regimen should be used in the remaining patients or when therapy with antibiotics other than penicillinase-resistant penicillins are used.330,739–744 When the conventional i.v. route therapy is not possible, S. aureus right-sided IE in PWID may also be treated with oral ciprofloxacin (750 mg twice a day) plus rifampin (300 mg twice a day) if the strain is susceptible to both drugs, the case is uncomplicated, and patient adherence is monitored carefully.745 Partial oral antibiotic treatment may also be beneficial for PWID with IE.746 For organisms other than S. aureus, therapy in PWID does not differ from that in other patients.

12.6.3.2 Surgery

The commonly accepted indications for surgical treatment of rightsided IE in patients who are receiving appropriate antibiotic therapy are (see Recommendation Table 19): • Persistent bacteraemia after at least 1 week of appropriate antibiotic therapy.10 • Tight ventricular dysfunction secondary to acute severe tricuspid regurgitation non-responsive to diuretics.479 • Respiratory insufficiency requiring ventilatory support after recurrent pulmonary emboli.747 • Involvement of left-sided structures;748,749 and • Large residual tricuspid vegetations (>20 mm) after recurrent pulmonary emboli.145,471

Patients should be individually assessed by the Endocarditis Team. An isolated vegetation is not an indication for surgery. Patients with Downloaded from academic.oup.com/eurheartj/article/44/39/3948/7243107 by guest on 07 October 2026