Tricuspid Valve Infective Endocarditis with Severe Tricuspid Regurgitation

Introduction

Infective endocarditis remains a life-threatening condition, with tricuspid valve infective endocarditis (TVIE) being particularly prevalent among individuals who engage in intravenous drug use (IVDU), accounting for approximately 30–40% of infective endocarditis cases in this population [1]. TVIE is associated with high morbidity due to complications such as severe tricuspid regurgitation (TR), septic pulmonary emboli, and right heart failure, with recurrence rates as high as 20–30% in IVDU patients due to ongoing substance use [2]. Early initiation of antimicrobial therapy and timely assessment for surgical intervention are critical to prevent complications such as vegetation growth and septic embolization [3]. The management of TVIE is complicated by challenges in ensuring treatment adherence, particularly in patients with substance use disorders. This case illustrates the clinical and social complexities of managing TVIE in an IVDU patient with chronic hepatitis C, highlighting the need for integrated medical and addiction support services to improve outcomes and prevent recurrence.

Case Report

Laboratory Investigations

LABORATORY INVESTIGATIONS:

A complete suite of diagnostic tests was performed to evaluate the patient’s condition. Complete blood count revealed leukocytosis (white blood cell count 15.2×109/L, 80% neutrophils), anemia (hemoglobin 9.5 g/dL), and normal platelet count (200×109/L). Renal function was normal (creatinine 0.9 mg/dL, eGFR 90 mL/min/1.73 m2). Blood cultures were obtained and were positive for methicillin-sensitive Staphylococcus aureus in 2 separate cultures. Chest X-ray showed patchy consolidation, worse in the left mid-zone, suggestive of infection. Electrocardiogram demonstrated sinus tachycardia with right axis deviation, but no ischemic changes. Troponin was mildly elevated at 0.05 ng/mL (normal <0.04 ng/mL). A computed tomography (CT) pulmonary angiogram confirmed bilateral pulmonary nodules consistent with septic emboli (Figure 1).

A transthoracic echocardiogram was performed, revealing:

A transesophageal echocardiogram was not performed due to the patient’s refusal of invasive procedures, limiting precise measurement of the vegetation size, although it was approximated via transthoracic echocardiogram. Groin ultrasound showed no drainable abscess.

DUKE CRITERIA FOR INFECTIVE ENDOCARDITIS: The patient met the criteria for definite infective endocarditis as per modified Duke criteria [4], with:

DIFFERENTIAL DIAGNOSIS:

The differential diagnosis was structured based on the following clinical and imaging findings.

TREATMENT:

Empirical intravenous vancomycin was initiated but later switched to flucloxacillin 2 g every 6 hours based on Staphylococcus aureus sensitivities. Supportive management included intravenous fluids, blood transfusions for anemia, and resumption of therapeutic rivaroxaban for recurrent embolic events.

COURSE OF HOSPITALIZATION:

The patient initially responded with reduced fever and improved chest pain, but persistent bacteremia prompted continuation of flucloxacillin. A psychiatric evaluation was performed to assess eligibility for involuntary hospitalization due to non-compliance and ongoing substance use, but the patient did not meet the criteria for involuntary admission due to intact decision-making capacity. He discharged against medical advice after 5 days. He returned 3 days later with worsening chest pain, dyspnea, new-onset bipedal edema, and persistent fevers. Repeat imaging revealed:

The patient initially consented to surgical intervention but later refused, citing fear of surgical complications and inability to abstain from drug use post-operatively. Discussions with addiction services were initiated, but the patient declined further engagement. Given worsening right heart failure, persistent bacteremia, and vegetation growth, cardiothoracic surgery was pursued but not completed due to the patient’s refusal.

OUTCOME AND FOLLOW-UP:

The patient was recommended for surgical intervention, but concerns about adherence to postoperative care were raised due to his history of non-compliance. Despite extensive counseling, he left the hospital before undergoing surgery, and follow-up was lost. This outcome highlights the critical need for structured addiction support and enhanced discharge planning to ensure continuity of care in IVDU patients.

Discussion

This case differs from typical TVIE cases due to the unusually large vegetation size (19 mm), non-compliance with anticoagulation leading to recurrent emboli, and the complexity of surgical decision-making given the patient’s history of discharging against medical advice. Most IVDU-associated TVIE cases involve vegetations ≤10 mm [5]. This case is notable for progressive vegetation growth to 19 mm, complicating right heart function and increasing the risk of catastrophic pulmonary embolism (Figure 3). Surgical intervention was indicated per American Heart Association (AHA) guidelines for large vegetations (>10 mm) and persistent bacteremia [6], yet adherence barriers prevented timely intervention.

The patient’s chronic hepatitis C was untreated, with no evidence of advanced liver disease, which did not directly impact management but increased infection risk due to immunosuppression. Antiviral therapy was not initiated during hospitalization due to prioritization of acute infection management.

Higher imaging modalities, such as transesophageal echocardiography, are recommended for TVIE when transthoracic echocardiography is inconclusive or to assess complications like abscesses or valve perforation, offering superior resolution for vegetation characterization [2]. In this case, transesophageal echocardiography was declined, limiting precise vegetation measurement and assessment of complications like abscesses. Surgical management is indicated for large vegetations (>10 mm), persistent bacteremia, or severe TR causing heart failure, as seen here [6,2]. Complications of infective endocarditis include heart failure (due to valve dysfunction), septic embolization (to lungs or systemic circulation), systemic infection (eg, abscesses), and embolic stroke, with TVIE particularly prone to pulmonary emboli due to right-sided involvement [2].

Alternative antibiotic regimens, such as oral or long-acting parenteral antibiotics (eg, dalbavancin or oritavancin), could have been considered, to facilitate outpatient treatment in this non-compliant patient, as supported by recent protocols for IVDU-associated endocarditis [7]. Additionally, addressing substance use disorder through a multidisciplinary approach, including referral to addiction counseling or opioid substitution therapy, could have improved adherence.

Compared with non-IVDU patients, IVDU patients with TVIE face higher recurrence rates (up to 30% within 1 year) due to ongoing drug use, but early surgical intervention offers similar benefits in both groups, including reduced mortality when vegetations exceed 10 mm [6]. However, IVDU patients face unique challenges, such as poor adherence and social barriers, necessitating tailored strategies like outpatient parenteral antimicrobial therapy (OPAT). Recurrence and poor compliance are common among IVDU patients, with studies reporting up to 30% recurrence within 1 year [2]. The decision to pursue surgery was based on vegetation size, persistent bacteremia, and worsening heart failure. Furthermore, alternatives like prolonged antibiotic therapy were considered to be likely to be less effective due to ongoing IVDU. Engagement with addiction services, such as OPAT clinics, has been shown to improve adherence in similar cases [8]. Community-based interventions, like mobile health units, have also facilitated follow-up care in IVDU populations [9]. Comparing this case to others in the literature, Ji et al (2012) reported recurrent TVIE due to non-compliance [10], while Cannon et al (2021) demonstrated successful outcomes with early surgery and addiction treatment [11].

The value of a multidisciplinary approach, including addiction counseling and OPAT, is critical to improving outcomes in IVDU patients with TVIE. OPAT has reduced readmissions significantly in this population [8]. In conclusion, this patient should ideally have been treated with a combination of prolonged intravenous antibiotics, followed by surgical intervention for the large vegetation and severe TR, integrated with comprehensive addiction treatment to ensure long-term compliance. Surgery could have been performed after completing outpatient treatment for addiction, such as through opioid substitution therapy or supervised rehabilitation programs, to mitigate risks of postoperative non-adherence and recurrence. However, this was not possible due to the patient’s acute worsening symptoms, persistent bacteremia despite antibiotics, repeated discharges against medical advice, refusal to engage with addiction services, and intact decision-making capacity that precluded involuntary admission. The AHA statement on managing endocarditis in IVDU patients emphasizes integrated care models combining medical and addiction support [12]. Potential improvements include earlier mandatory involvement of addiction specialists upon admission, utilization of long-acting antibiotics such as dalbavancin with outpatient management to reduce hospital stays and enhanced patient education on risks.

Conclusions

This case underscores the multifaceted challenges in managing TVIE among IVDUs, particularly concerning treatment adherence, anticoagulation management, and surgical decision-making. Key lessons include the need for early addiction counseling to address substance use, structured follow-up through OPAT or mobile health units to ensure antibiotic completion, and clear communication to enhance patient trust and compliance. Future research should explore scalable models for integrating addiction and medical care to reduce recurrence and improve survival in this high-risk population.