From the Guidelines
The primary distinction between subacute and acute infective endocarditis is rooted in their clinical presentation, progression, and causative pathogens, with acute endocarditis being more aggressive and requiring immediate intervention, as opposed to the more indolent subacute form. The difference in clinical presentation is crucial for guiding treatment approaches. Acute infective endocarditis typically presents over days to weeks, is often caused by more virulent organisms such as Staphylococcus aureus, β-hemolytic streptococci, and aerobic Gram-negative bacilli 1, and is characterized by severe systemic symptoms and rapid progression to heart failure. In contrast, subacute infective endocarditis progresses over weeks to months, is usually caused by less virulent organisms including Streptococci, HACEK organisms, and enterococci 1, and presents with more subtle symptoms such as low-grade fever, night sweats, and weight loss.
Key differences in management approaches include:
- The need for broad-spectrum antibiotic coverage in acute cases to cover for S aureus, β-hemolytic streptococci, and aerobic Gram-negative bacilli 1.
- The consideration of less virulent pathogens in subacute cases, thus covering for S aureus, VGS, HACEK, and enterococci 1.
- The potential for more frequent urgent surgical intervention in acute endocarditis due to rapid valve destruction.
- The importance of consultation with an infectious diseases specialist, especially in culture-negative endocarditis cases, to define the most appropriate therapy 1.
Given these distinctions, it is crucial to accurately diagnose and manage infective endocarditis based on its acute or subacute presentation to improve patient outcomes in terms of morbidity, mortality, and quality of life. This involves not only appropriate antimicrobial therapy but also consideration of the patient's overall clinical course, severity of infection, and potential for complications 1.
From the Research
Definition and Classification
- Infective endocarditis (IE) is a condition where the endocardial surface of the heart becomes infected, and it can be classified into two main categories: acute and subacute.
- Acute infective endocarditis is characterized by a sudden onset of symptoms, typically with a high fever, chills, and heart valve damage 2.
- Subacute infective endocarditis, on the other hand, has a more gradual onset of symptoms, often with a lower fever and less severe heart valve damage.
Clinical Manifestations
- The clinical manifestations of IE can involve every organ system, and the cardiac manifestations can include valvular vegetation, abscess, periannular extension of infection, and myopericarditis 2.
- Patients with subacute IE may have symptoms for longer than three months, which can lead to a higher relapse rate and mortality compared to those with symptoms for less than three months 3.
Treatment
- The treatment of IE depends on the causative organism and the severity of the disease.
- Patients with penicillin-sensitive viridans or nonenterococcal group D streptococcal endocarditis may be treated successfully with aqueous penicillin G alone for four weeks or with combined penicillin and streptomycin for two weeks 4.
- Patients with enterococcal endocarditis should be treated for four to six weeks with a combination of aqueous penicillin G together with either streptomycin or gentamicin 4, 3.
- In cases of penicillin-resistant viridans group streptococcal endocarditis, antibiotic combination including a beta-lactam seems to be effective in its management 5, 6.
Prognosis
- The prognosis of IE depends on various factors, including the causative organism, the severity of the disease, and the promptness of treatment.
- Patients with subacute IE may have a higher relapse rate and mortality compared to those with acute IE, especially if they have symptoms for longer than three months 3.
- The use of gentamicin-associated nephrotoxicity should be monitored, as it can be more frequent among patients treated with more than 3 mg/kg per day of gentamicin 3.