General Cardiology

Etiologies and Characteristics of Infective Endocarditis in PWID

Jessica Nye, PhD
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Staphylococcus aureus is a rare cause of myocarditis and typically affects immunocompromised patients with sepsis. S aureus myocarditis usually occurs with endocarditis and may result in the formation of abscesses on the heart valves and muscle.5 “As with viral myocarditis, this disease can present with signs and symptoms of acute myocardial infarction, complicating the diagnosis,” wrote the authors of a 2008 case study.12 “Much of the available data on bacterial myocarditis [were] collected before the development of many modern diagnostic tests and before antibiotics [thus] the appropriate workup, diagnosis and treatment remain unclear.”12 A case report published in 2018 described a 44-year-old man with rheumatoid arthritis taking methotrexate who was diagnosed with S aureus myocarditis (and associated left ventricular apical thrombus) after having septic shock.13 Complete recovery was achieved with a 12-week course of antibiotics and anticoagulation.

Staphylococcus aureus is a rare cause of myocarditis and typically affects immunocompromised patients with sepsis. S aureus myocarditis usually occurs with endocarditis and may result in the formation of abscesses on the heart valves and muscle.5 “As with viral myocarditis, this disease can present with signs and symptoms of acute myocardial infarction, complicating the diagnosis,” wrote the authors of a 2008 case study.12


“Much of the available data on bacterial myocarditis [were] collected before the development of many modern diagnostic tests and before antibiotics [thus] the appropriate workup, diagnosis and treatment remain unclear.”12 A case report published in 2018 described a 44-year-old man with rheumatoid arthritis taking methotrexate who was diagnosed with S aureus myocarditis (and associated left ventricular apical thrombus) after having septic shock.13 Complete recovery was achieved with a 12-week course of antibiotics and anticoagulation.

Etiologies and characteristics of infective endocarditis in people who inject vs those do not inject drugs were found to significantly differ.

Etiologies and characteristics of infective endocarditis (IE) in people who inject (PWID) vs those do not inject drugs were found to significantly differ, according to a study published in the Journal of the American College of Cardiology.

In this observational, prospective cohort study, data were sourced from the ICE-Prospective Cohort Study and the ICE-Plus databases and collected between 2000 and – 2006 and between 2008 and 2012 from 28 and 18 countries, respectively. PWID  and non- PWID with IE (n=7025 and n=591m respectively; mean age, 37.0 years and 63.3 years, respectively; P <.001; 67.4% men and 72.5% men, respectively; P =.007) were assessed for source of infection and outcomes. Relapse was defined as new IE caused by the same micro-organism within 6 months, and persistent bacteremia was defined as positive blood cultures despite 72 hours of antibacterial treatment.

Patients in the non-PWID vs PWID group had significantly more comorbidities (P <.001 for all), except for human immunodeficiency virus and liver disease, which were more common among PWID (P £.002 for both).

Among the PWID and non-PWID groups, IE involved native valves (90.2% vs 64.4%, respectively; P <.001) or prosthetic valves (9.3% vs 27.0%, respectively; P <.001), specifically the tricuspid (56.2% vs 18.3%, respectively; P <.001), mitral (24.9% vs 29.9%, respectively; P =.007), or aortic (20.8% vs 34.1%, respectively; P <.001) valves. Infections were primarily caused by Staphylococcus aureus (S aureus; 65.9% vs 25.6%, respectively; P <.001), methicillin-resistant S aureus (14.5% vs 29.0%, respectively; P <.001), coagulase-negative staphylococci (14.5% vs 29.0%, respectively; P <.001), or viridans group streptococci (9.5% vs 18.6%, respectively; P <.001), respectively.

PWID had higher rates of intracardiac vegetations and lower rates of abscesses, intracardiac fistulas, or severe regurgitation compared with non-PWID (P <.001 for all). Fewer PWID vs non-PWID were treated with surgery (39.5% vs 47.8%, respectively; P <.001).

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Systemic embolization (50.1% vs 22.1%, respectively; P <.001), pulmonary emboli (30.6% vs 4.2%, respectively; P <.001), and persistent bacteremia (14.0% vs 8.8%, respectively; P <.001) were elevated in PWID compared with non-PWID and congestive heart failure (23.7% vs 31.1%, respectively; P <.001) was lower.

Risk for stroke (P <.001), congestive heart failure (P <.001), and 6-month mortality (P =.010) was increased in PWID with left-sided IE, and systemic embolization was greater in PWID with right-sided IE (P =.021).

PWID living in North America were at increased risk for IE relapse (odds ratio [OR], 3.19; 95% CI, 1.40-7.24; P =.006), and those who had a stroke (OR, 3.86; 95% CI, 2.00-7.46; P <.001), had a previous IE (OR, 2.51; 95% CI, 1.26-4.97; P =.009), intracardiac complications (OR, 2.62; 95% CI, 1.17-5.90; P =.002), left-sided IE (OR, 1.89; 95% CI, 1.01-3.52; P =.04), or polymicrobial IE (OR, 3.98; 95% CI, 1.04-15.18; P =.04) were at increased risk for mortality at 6 months.

This study may have been biased by the greater inclusion of patients who received surgery for IE, as all participating centers were surgical referral centers.

“Approaching PWID with a respectful attitude and offering the possibility of cardiac surgery when indicated, together with the adequate harm reduction services and drug abuse disorder treatment, are crucial management elements,” concluded the study authors/

Reference

Pericàs J M, Llopis J, Athan E, et al. Prospective Cohort Study of Infective Endocarditis in People Who Inject Drugs. J Am Coll Cardiol. 2021;77(5):544-555. doi:10.1016/j.jacc.2020.11.062

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