Endocarditis: the great mimic of rheumatic diseases

Cranial giant cell arteritis mimickers: A masquerade to unveil

Giant cell arteritis (GCA) is a large-vessel vasculitis that affects cranial and extra-cranial arteries. Extra-cranial GCA presents mainly with non-specific symptoms and the differential diagnosis is very broad, while the cranial form has more typical clinical picture and physicians have a lower threshold for diagnosis and treatment. Although temporal artery biopsy (TAB) has an established role, ultrasound (US) is being increasingly used as the first-line imaging modality in suspected GCA. Vasculitides (especially ANCA-associated), hematological disorders (mainly amyloidosis), neoplasms, infections, atherosclerosis and local disorders can affect the temporal arteries or might mimic the symptoms of cranial GCA and produce US and TAB findings that resemble those of temporal vasculitis. Given that prompt diagnosis is essential and proper treatment varies significantly among these diseases, in this review we aimed to collectively present disorders that can masquerade cranial GCA.

Mechanisms of thrombosis in ANCA-associated vasculitis

Patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) have a two- to threefold greater risk of developing venous as well as arterial thrombotic events. Although such thrombotic events are more commonly seen during phases of active AAV, they are also recognized to occur during AAV in remission. Endothelial injury is a key pathogenic event in AAV. Endothelial injury can be caused by neutrophil activation and release of thrombogenic tissue factor into the circulation. Neutrophil activation further results in the formation of neutrophil extracellular traps (NETs). NETs contribute to thrombosis by expressing tissue factor. NETs have also been detected in cutaneous thrombi from patients with AAV induced by hydralazine. Activated neutrophils in AAV patients release thrombogenic microparticles loaded with tissue factor which further enhances clotting of blood. Antiphospholipid antibodies (APLs) have been detected in up to a third of AAV and might also be induced by drugs such as cocaine adulterated with levamisole and propylthiouracil, which are known to trigger AAV. Such APLs further drive the thrombosis in AAV. Once thrombogenesis occurs, the homeostatic mechanisms resulting in clot dissolution are further impaired in AAV due to anti-plasminogen antibodies. The ongoing pandemic of coronavirus disease 2019 (COVID-19) is associated with endothelial injury and NETosis, mechanisms which are in common with AAV. Reports of new-onset AAV following COVID-19 have been described in the literature, and there could be shared mechanisms driving these processes that require further evaluation.

Clinical usefulness of FDG-PET/CT for identification of abnormal extra-cardiac foci in patients with infective endocarditis

The aim of the study was to evaluate the ability to detect extra-cardiac foci by means of whole-body ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in patients with definite endocarditis (IE) according to the modified Duke criteria and investigate the clinical impact of the findings. From January 2011 to December 2015 we included 178 patients (mean age 66 ± 14 years, 25% female) with IE in this multicentre study. FDG-PET/CT was part of the work-up for extra-cardiac foci in the including hospitals and was performed at a median of 9 days (IQR 10) after IE was diagnosed. In 114 patients FDG-PET/CT identified 166 lesions: 52 (31%) infectious lesions, 21 (13%) cases of cancer, 7 (4%) cases of embolism, 60 (36%) reactive findings, and 26 (16%) other types of lesions. A total of 74 new extra-cardiac findings, not previously discovered by other modalities, were identified in 62 patients and resulted in additional investigations in 29 patients and a change in treatment in 18 patients (10%). The most frequent diagnoses discovered by FDG-PET/CT were colon polyps, cancer, and spondylodiscitis. There was a higher rate of findings leading to a change in treatment in patients above 67 years of age infected with other bacterial aetiologies than streptococci. FDG-PET/CT was useful to detect extra-cardiac foci. FDG-PET/CT findings may lead to unnecessary investigations. One out of 10 the patients with definite endocarditis had underwent a change in treatment regimen based on the FDG-PET/CT findings.

Clinical characteristics of infective endocarditis in patients with antineutrophil cytoplasmic antibody or antiphospholipid antibody: a retrospective study in Shanghai

OBJECTIVE

This study aimed to characterise rheumatic manifestations and autoantibodies in 432 patients diagnosed with infective endocarditis (IE) in Shanghai.

DESIGN, SETTING AND PARTICIPANTS

A retrospective study was conducted in Ruijin Hospital from 1997 to 2017. The clinical and laboratory characteristics of a total of 432 patients were analysed. In addition, the differences between patients with positive and negative antineutrophil cytoplasmic antibodies (ANCA) and antiphospholipid (aPL) antibodies as well as the survival rates of these patients were compared.

RESULTS

A total of 432 patients, including 278 male patients and 154 female patients, were included. The mean age of the patients was 46±16 years. A total of 346 patients (80%) had cardiac surgery, and 55 patients (13%) died in the hospital. Among the IE patients, 104 were tested for either ANCA or aPL and were analysed in different groups. Twenty-one (24%) positive ANCA patients were proteinase 3-ANCA positive. Compared with the ANCA-negative group, patients with positive ANCA had higher IgM (p=0.048), lower haemoglobin (p=0.001) and a higher likelihood of arthritis (p=0.003). Twenty-one (40%) aPL-positive patients had a higher erythrocyte sedimentation rate than was found in the aPL-negative group (p=0.003). In addition, the survival rate of the ANCA-positive IE patients was lower (p=0.032) than that of the ANCA-negative group, while there was no difference between patients with or without aPL antibodies (p=0.728).

CONCLUSION

This study supports the claim that rheumatic manifestations and autoantibodies are frequently present in patients with IE and might lead to early misdiagnosis. Physicians should pay more attention to the measurement of autoantibodies in these patients.

Autoimmune manifestations of infections

PURPOSE OF REVIEW

To provide an update about the interactions between infections and autoimmune diseases (AIDs), from the molecular perspective to the clinical spectrum and the differentiation between infection and disease activity.

RECENT FINDINGS

Any kind of infection may modify the innate and adaptive immune response through the following mechanisms: molecular mimicry, superantigens, epitope spreading and B-cell activation. The consequence is the overproduction of antibodies shared with those found in AIDs. Viral infections, especially HIV and hepatitis C virus, can stimulate the production of antiphospholipid antibodies and confer an increased risk to develop antiphospholipid syndrome.

SUMMARY

The identification of risk factors to develop infections in patients with AIDs is remarkable to prevent them. These factors are the use of steroids and immunosuppressants, the involvement of a major organ (lungs, brain and kidney) and severe activity. Biomarkers to differentiate infection from disease activity are scarce, but the combination of procalcitonine and C-reactive protein seems to have higher specificity and sensibility to identify infections in patients with AIDs. Finally, the clinical judgment is the hallmark to differentiate between infections and disease activity.

CT and MR Imaging of Cardiothoracic Vasculitis

The term vasculitis includes a variable group of entities in which the common characteristic is inflammation of the walls of blood vessels occurring at some time during the course of the disease. The vasculitides can be divided into primary and secondary vasculitides, depending on the etiology and according to the size of the vessel affected. Both primary vasculitis and secondary vasculitis are associated with cardiac morbidity that is often subclinical. Cardiac involvement is associated with prognostic implications and higher rates of related mortality. Vasculitis of cardiac structures and the assessment of disease extent are important for appropriate management and selection of treatment. Although echocardiography, radionuclide imaging, and catheter-directed coronary angiography remain the cornerstones of cardiac imaging, cardiac computed tomography and magnetic resonance imaging can offer a 360° assessment of cardiac anatomy, function, and complications secondary to vasculitis. Postoperative complications, which are more frequent in patients with active disease, can also be depicted with those imaging modalities. A multidisciplinary approach is important to yield an appropriate estimate of the disease activity and extent and, therefore, to enable better treatment selection and monitoring. Online supplemental material is available for this article. ^©RSNA, 2018.