European Journal of Cardiovascular Medicine

Infective endocarditis (IE) is a multifaceted disease characterized by cardiac involvement and a spectrum of systemic complications affecting multiple organs. With an annual incidence reaching up to 10 cases per 100,000 individuals in the general population, IE remains a formidable clinical challenge. Despite advancements in diagnosis and management, the condition continues to carry a significant burden, with mortality rates soaring as high as 30% within the first 30 days ⁽¹⁾. Staphylococcus aureus is the most common causative microorganism. The prognosis of this disease depends on prompt and accurate diagnosis that leads to an aggressive therapeutic management combining antibiotic therapy and early cardiac surgery when indicated. Diagnosis of IE is usually based on modified Duke criteria ⁽²⁾. There are multiple modalities to assess infective endocarditis with trans-thoracic echocardiography (TTE) being the first-line modality. The improved temporal and spatial resolution of electrocardiographically (ECG) synchronized cardiac CT has resulted in increasing use of CT in the setting of IE ⁽³⁾.

A 63-year-old male with a known history of diabetes mellitus (HbA1C: 10.5) presented with a four-day history

of fever, along with pain and swelling in both upper and lower limbs. Laboratory investigations revealed an elevated total leukocyte count (TLC) of 28,610cells/ and a serum creatinine level of 1.4 mg/dL.

Initial clinical evaluation suggested cellulitis, and the patient was promptly initiated on empirical antibiotic therapy in accordance with the hospital's antibiotic policy. A routine TTE demonstrated concentric left ventricular hypertrophy with preserved left ventricular systolic function, with no evidence of emboli or vegetations. However, the fever persisted, and the patient subsequently developed Janeway lesions and Osler’s nodes. Additionally, progressive gangrene of the toes on both feet was noted. Blood cultures yielded significant growth of Staphylococcus aureus. Given the clinical suspicion of infective endocarditis with septic emboli, a repeat echocardiogram was performed, revealing a mass attached to the posterior mitral leaflet, highly suggestive of thrombus or vegetation. In light of the persistent fever and digital gangrene, cardiac CT was recommended for further evaluation (Figure 2 to 5)

Figure 1: Apical four chamber view of TTE demonstrating a bullous vegetation (Orange arrow) adherent to the posterior aspect of mitral valve (Blue arrow).

Figure 2: Cardiac CT demonstrating a well-defined soft tissue attenuating lesion in the left ventricle, and its attachment to the inferior aspect of the posterior mitral leaflet (purple arrow).

Figure 3a                                                                                       Figure 3b

Figure 3a and 3b: Cardiac CT in short axis view (3a) and inferior 4 chamber view (3b) demonstrates a soft tissue hypodense thickening in the posterolateral aspect of mitral annulus extending to posterior left atrioventricular groove (Blue arrow).

  Figure 4a                                                                                                Figure 4b

Figure 4a and 4b: Cardiac CT in inferior 4 chamber view demonstrating a soft tissue hypodensity is noted encasing the left circumflex artery (orange arrow in figure 4a) and displacing the coronary sinus (blue arrow in figure 4b).

 Figure 5a                                                                                       Figure 5b

Figure 5a and 5b: Cardiac CT demonstrating a contrast filled outpunching in the posterior left AV groove, arising posteroinferior to the posterior mitral leaflet

INVESTIGATIONS   

   Laboratory Tests

Microbiological Studies

Imaging Studies

Clinical Findings Suggestive of Septic Embolism

TREATMENT

Injection vancomycin was given for 6 weeks and plan for surgery, post stabilization. Repeat blood culture was negative. However regular monitoring of S. creatinine showed worsening of renal failure and the antibiotics were changed to Injection Cloxacillin 3mg. Later in his hospital course, ECG changes suggesting 1st degree block was noted with features of worsening renal and cardiac failure.

OUTCOME/ FOLLOW UP

 Patient developed pulmonary edema and heamodialysis was suggested in view of renal failure and volume overload. However the serum creatinine increased and patient was suggested sustained low-efficiency dialysis (SLED). During dialysis his Glasgow Coma Scale (GCS) dropped and he was intubated. Bradycardia and hypotension was noted and CPR was initiated. The patient passed away shortly thereafter from multiorgan failure.

An infection of the heart's endothelium is known as infectious endocarditis (IE). It has a 30-day death rate of up to 30% and affects 3–10 out of every 100,000 people annually. The epidemiology of IE has changed over time, and because of the growing use of intravenous lines and intracardiac devices, healthcare-associated IE currently accounts for 25–30% of all occurrences. About 26.6% of IE cases are now caused by Staphylococcus aureus, with

viridans group streptococci accounting for 18.7%, other streptococci for 17.5%, and enterococci for 10.5% ⁽¹⁾. Native valve endocarditis, endocarditis in intravenous drug users, and prosthetic valve endocarditis are the three types of endocarditis. Fever, vegetation on echocardiogram, and positive blood cultures are all necessary for the diagnosis of IE. The percentage of negative blood cultures is anticipated to be less than 5% since IE patients have persistent low-level bacteremia. Negative cultures may arise from bacterial infections like Legionella, Coxiella, and the HACEK group (Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae), as well as fungal infections like Candida, Histoplasma, and Aspergillus ⁽⁷⁾. The modified Duke's criteria, which include clinical, biochemical, and echocardiographic observations, are commonly used to diagnose infective endocarditis. Nevertheless, these criteria do not include cardiac computed tomography (CT) as a diagnostic technique. Transthoracic echocardiogram (TTE) and transesophageal echocardiography (TEE) failed to detect vegetations and a perivalvular abscess, whereas cardiac CT successfully revealed in this case of infective endocarditis ⁽⁶⁾. In the assessment of IE, cardiac CT is a useful adjunct to echocardiography rather than a substitute. Nonetheless, cardiac CT is especially helpful for individuals who cannot use TEE or who have a high suspicion of IE but have unsatisfactory echocardiography results because of prosthetic valves or calcifications. Heart CT is now part of the 2015 European Society of Cardiology's updated diagnostic criteria for IE ⁽³⁾. In order to diagnose infective endocarditis, we used cardiac CT to find vegetations, subvalvular pseudoaneurysms, and perivalvular abscesses that echocardiography was unable to identify. Two clinical insights resulted from this: first, CT is a practical imaging technique for identifying perivalvular abscesses and vegetations in the diagnosis of infective endocarditis. Second, when repeated echocardiography in suspected cases of infective endocarditis produces negative results, CT can be used in conjunction with echocardiogram to evaluate and diagnose the condition ⁽⁶⁾. Atypical findings are frequent, and in 15% of instances of infective endocarditis, echocardiography may produce false negative results, particularly if there are pre-existing severe lesions, such as prosthetic valves, degenerative lesions, or mitral valve prolapse ⁽⁸⁾. The morphology of the patient, the instrument settings, the position of the transducer, the operator's skill, and artifacts from metallic prosthetic valves and heavy valve calcifications through acoustic shadowing all restrict the diagnostic potential of echocardiography. CT, on the other hand, can reconstruct images from a variety of angles regardless of certain variables, such as operator skill or patient morphology. Conscious sedation is usually used during the semi-invasive procedure known as transesophageal echocardiography (TEE). TEE has a 0.88% complication rate, which includes risks for cardiac arrhythmias, hypotension, hemorrhage, perforation, sedation/anesthesia-related events, and mortality ⁽⁹⁾. CT, on the other hand, is a noninvasive, safe technique that enables quick scanning with little patient assistance. In a single examination, it can diagnose peripheral embolic events and evaluate the coronary artery structure. Treatment decisions for infective endocarditis are greatly influenced by the accurate and timely evaluation of both cardiac and extracardiac lesions. Consequently, CT is a useful imaging technique for noninvasively assessing the coronary artery architecture, extracardiac lesions, and valvular and perivalvular involvement ⁽⁶⁾.

Cardiac CTA has drawbacks despite its benefits. Risks are associated with radiation exposure and contrast agent use, especially for individuals who have iodinated contrast allergies or renal insufficiency. Furthermore, Cardiac CTA's accessibility and the requirement for specific tools and knowledge can prevent it from being widely used. However, given its low invasiveness and capacity to identify vegetations and perivalvular problems, cardiac CT may be a good choice for assessing infective endocarditis, especially in cases when repeated echocardiography produces null results.

To sum up, cardiac CT angiography is a major improvement in the diagnostic assessment of infective endocarditis. It is a vital tool in the modern diagnostic toolbox because of its capacity to evaluate extracardiac problems, give precise anatomical imaging, and supplement conventional echocardiographic procedures. Despite its drawbacks, the use of CTA in clinical settings can improve patient outcomes in cases of infective endocarditis by improving diagnostic precision and directing treatment choices. The function of CTA in the diagnosis and treatment of this complicated disorder is probably going to continue to be improved and expanded by future research and developments in imaging technology.

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