(P094) PERCUTANEOUS MECHANICAL ASPIRATION IN ENDOCARDITIS

Case background: Infective endocarditis (IE) is a condition with high morbidity and mortality that has increasing prevalence within Saskatchewan communities. Between 2006 and 2016, the number of admissions with IE doubled at the two tertiary hospitals in Saskatoon. People who inject drugs (PWID) appear to be driving this increase in cases. These patients, who commonly present with right-sided or tricuspid valve IE (TVIE), are often deemed poor candidates for surgery despite being younger and having more advanced disease at presentation. Historically, antibiotic therapy and adjunctive surgical intervention were the only definitive options for management of IE, but there is an increasing need for other synergistic therapy options when medical therapy fails. Percutaneous mechanical aspiration (PMA) is emerging as an alternative adjunctive therapy for right-sided IE in select cases, specifically in poor surgical candidates or pacemaker-related infections, which may also be useful in patients at high risk of re-infection, such as PWID.

We reviewed a case of a 26-year-old female PWID with native TVIE. She was the first patient in Saskatchewan’s history to undergo PMA for TVIE. Presenting initially to a rural hospital in July 2023 with sepsis, her blood cultures were positive for Enterobacter cloacae complex and transthoracic echo showed a 1.8 cm vegetation on her tricuspid valve with moderate tricuspid regurgitation. She had a past medical history of opioid use disorder (OUD) and continued to inject morphine daily, resulting in multiple complications including prior septic arthritis, paraspinal and parapharyngeal abscesses, and hepatitis C. Despite a patient-directed discharge from hospital before completing intravenous antibiotic therapy, she ultimately completed a disjointed 6-week course of meropenem during a subsequent admission.

Over the next four months, she had three more separate admissions to hospital. She developed recurrent polymicrobial bloodstream infections due to insufficient courses of antibiotics and sub-optimally treated OUD. She was ultimately transferred to Saskatoon in November 2023 with E. faecalis bacteremia and TVIE complicated by pulmonary septic emboli and right heart failure. Echocardiography revealed two significantly larger tricuspid valve vegetations, measuring 2.7 cm and 2.3 cm, accompanied by torrential tricuspid regurgitation. Although cultures cleared after 72 hours of antibiotic therapy, there was concern of recurrence with medical therapy alone. Our local Multi-disciplinary ENDOcarditis clinical pathway (MENDO) was activated and she underwent successful suboxone initiation in hospital after being seen by the addictions medicine team. Moreover, the MENDO team, including a cardiac surgeon and cardiologist, concluded that a bridging procedure like PMA would be most appropriate for source control given relatively preserved right ventricular function. This, in turn, would give her more time for addictions management and psychosocial stabilization.

PMA is an emerging adjunctive therapy for right-sided IE allowing removal of cardiac vegetations less invasively than surgery. It can potentially improve blood culture clearance and reduce the risk of septic emboli and re-infection. In this case, the AlphaVac device (AngioDynamics®) was used to aspirate two tricuspid valve vegetations. Procedural risks included blood loss, with 10 to 30 mL of blood removed per aspiration, and embolization of vegetations not captured by the device. Worsening of valvular regurgitation following the procedure has also been described in some case studies. The procedure was performed in the catheterization lab by Dr. Jason Orvold under general anesthesia. Transesophageal ultrasound was used to visualize the tricuspid vegetations in real time. The AlphaVac device was guided fluoroscopically through its entry into the right internal jugular vein to the right atrium. The patient did not have any significant interatrial shunt. Both vegetations were successfully aspirated with a small residual vegetation on one of the tricuspid leaflets (Figure 1). She received one unit of blood post-procedure for a drop in hemoglobin from 79 to 72 g/L. There were no other complications.

Following the procedure, her blood cultures remained persistently clear. Pathology of the aspirated vegetations showed calcified fibrous tissue with abundant neutrophils but no viable bacteria cultured. A week later, she was transferred to her home hospital for antibiotic completion and engagement with her local community services and addictions programs. Upon discharge, her heart failure symptoms improved and her 6-week antibiotic course was completed with minimal interruptions; since then, she has had no recurrence of bacteremia in subsequent presentations to hospital. Currently, she is connected with a cardiologist for ongoing monitoring and decision-making around timing of tricuspid valve replacement.

Management Challenges: This case demonstrates the challenges of caring for patient populations with a history of marginalization in health care settings, such as PWID. It highlights the importance of multi-disciplinary management in TVIE, including addressing risk factors with addictions medicine involvement for suboxone initiation. Cardiology and cardiac surgery consultation were key for assessing the feasibility of adjunctive options beyond medical therapy. Multiple attempts at medical therapy alone had been unsuccessful in this patient, leading to her presentation with enlarged vegetations, significant burden of septic emboli and right heart failure. The deployment of PMA allowed for more definitive management of the patient’s TVIE, potentially reduced risk of re-infection, and expediated repatriation to her community. Further research is required to standardize the use of PMA in TVIE.

PMA has been primarily studied in the context of persistently positive blood cultures not clearing with medical therapy. An emerging indication described here is in cases of enlarging vegetations despite appropriate courses of antibiotics without positive cultures. Although this is currently a class 1C recommendation for surgical treatment based on recent guidelines, this must be weighed against persistent psychosocial factors predicting re-infection (e.g. homelessness, lack of harm reduction materials and addictions support). Indeed, a large vegetation and the surrounding turbulent blood flow creates a highly susceptible environment for bacterial inoculation in any subsequent transient bacteremia. Therefore, de-bulking sterile vegetations may reduce the risk of re-infection and re-admission. This will be the focus of further study. Comparison of AlphaVac outcomes with valve surgery are also needed to inform best practices. Altogether, PMA certainly appears to hold promise for PWID who are superusers of the medical system and face multiple systemic barriers to appropriate care.