Clinical features and prognosis of isolated cardiac sarcoidosis diagnosed using new guidelines with dedicated FDG PET/CT

Role of Textural Analysis Parameters Derived from FDG PET/CT in Diagnosing Cardiac Sarcoidosis

Introduction  Texture and radiomic analysis characterize the lesion's phenotype and evaluate its microenvironment in quantitative terms. The aim of this study was to investigate the role of textural features of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) images in differentiating patients with cardiac sarcoidosis (CS) from patients with physiologic myocardial uptake. Methods  This is a retrospective, single-center study of 67 patients, 17 diagnosed CS patients, and 50 non-CS patients. These patients underwent FDG PET/CT for the diagnosis of CS. The non-CS group underwent 18F-FDG PET/CT for other oncological indications. The PET/CT images were then processed in a commercially available textural analysis software. Region of interest was drawn over primary tumor with a 40% threshold and was processed further to derive 92 textural and radiomic parameters. These parameters were then compared between the CS group and the non-CS group. Receiver operating characteristics (ROC) curves were used to identify cutoff values for textural features with a p -value < 0.05 for statistical significance. These parameters were then passed through a principle component analysis algorithm. Five different machine learning classifiers were then tested on the derived parameters. Results  A retrospective study of 67 patients, 17 diagnosed CS patients, and 50 non-CS patients, was done. Twelve textural analysis parameters were significant in differentiating between the CS group and the non-CS group. Cutoff values were calculated for these parameters according to the ROC curves. The parameters were Discretized_HISTO_Entropy, GLCM_Homogeneity, GLCM_Energy, GLRLM_LRE, GLRLM_LGRE, GLRLM_SRLGE, GLRLM_LRLGE, NGLDM_Coarseness, GLZLM_LZE, GLZLM_LGZE, GLZLM_SZLGE, and GLZLM_LZLGE. The gradient boosting classifier gave best results on these parameters with 85.71% accuracy and an F1 score of 0.86 (max 1.0) on both classes, indicating the classifier is performing well on both classes. Conclusion  Textural analysis parameters could successfully differentiate between the CS and non-CS groups noninvasively. Larger multicenter studies are needed for better clinical prognostication of these parameters.

Diagnosis and Prognosis of Isolated Cardiac Sarcoidosis: Multidisciplinary Diagnosis Versus Japanese Circulation Society Criteria

The prognosis of isolated cardiac sarcoidosis (ICS) has not been fully elucidated. The only diagnostic criteria available for ICS, the Japanese Circulation Society (JCS) criteria, have not been validated. We aimed to study the prognosis of ICS according to 2 different diagnostic strategies. We prospectively included patients with a high suspicion for cardiac sarcoidosis by a multidisciplinary sarcoidosis team from November 2016 to June 2021. We included only incident cases. We applied the JCS ICS criteria and our multidisciplinary diagnosis (MDD) ICS criteria. We included 198 incident patients who had a final diagnosis of cardiac sarcoidosis. The median follow-up time was 2.4 years (twenty-fifth to seventy-fifth percentile: 1.2 to 3.7). The prevalence of ICS was 7% (14 of 198) per the JCS criteria and 29% (57 of 198) per our MDD criteria. Compared with patients with non-ICS, patients with ICS per either criterion had similar rates of major cardiovascular outcomes (progression of atrioventricular block, worsening ejection fraction ≥10%, appropriate implantable cardioverter-defibrillator therapies, heart transplant, and death). The Kaplan-Meier analyses showed similar prognosis for ICS and non-ICS in all outcomes, except for an association between ICS by MDD criteria and a shorter time to cardiac hospitalization. The multivariable Cox regression analyses showed that ICS was not an independent predictor of death, heart transplant, or clinical worsening. In conclusion, our MDD ICS criteria were more inclusive than the JCS ICS criteria. The prognosis was similar between patients with ICS and patients with non-ICS, regardless of which criteria were used.

Different Impact of Immunosuppressive Therapy on Cardiac Outcomes in Systemic Versus Isolated Cardiac Sarcoidosis

Isolated cardiac sarcoidosis (iCS) is increasingly recognized; however, its prognosis and the efficacy of immunosuppressive therapy remain undetermined. We aimed to compare the prognosis of iCS and systemic sarcoidosis including cardiac involvement (sCS) under immunosuppressive therapy.We retrospectively reviewed the clinical data of 42 patients with sCS and 30 patients with iCS diagnosed at Kyushu University Hospital from 2004 through 2022. We compared the characteristics and the rate of adverse cardiac events including cardiac death, fatal ventricular tachyarrhythmia, and heart failure hospitalization between the 2 groups. The median follow-up time was 1535 [interquartile range, 630-2555] days, without a significant difference between the groups. There were no significant differences in gender, NYHA class, or left ventricular ejection fraction. Immunosuppressive agents were administered in 86% of sCS and in 73% of iCS patients (P = 0.191). When analyzed only with patients receiving immunosuppressive therapy (sCS, n = 36; iCS, n = 21), the cardiac event-free survival was significantly lower in iCS than sCS (37% versus 79%, P = 0.002). Myocardial LGE content at the initial diagnosis was comparable in both groups. The disease activity was serially evaluated in 26 sCS and 16 iCS patients by quantitative measures of FDG-PET including cardiac metabolic volume and total lesion glycolysis, representing 3-dimensional distribution and intensity of inflammation in the entire heart. Although iCS patients had lower baseline disease activity than sCS patients, immunosuppressive therapy did not attenuate disease activity in iCS in contrast to sCS.iCS showed a poorer response to immunosuppressive therapy and a worse cardiac prognosis compared to sCS despite lower baseline disease activity.

Current Practices and Emerging Therapies to Optimize Heart Failure Management in Cardiac Sarcoidosis: A Systematic Review

Cardiac sarcoidosis (CS) is a distinctive manifestation of sarcoidosis, a multisystemic inflammatory disorder that is characterized by non-necrotizing granulomas. CS can lead to arrhythmias, heart failure (HF), and sudden cardiac death. The diagnosis of CS involves imaging in the form of a two-dimensional echocardiogram, cardiac magnetic resonance imaging (MRI), an 18-fluoro-deoxyglucose positron emission tomography (FDG-PET) scan, and an endomyocardial biopsy. Treatment of CS entails corticosteroids, immunosuppressive agents, monoclonal antibodies, and, in advanced cases, heart transplantation (HTx). This systematic review follows Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, focusing on HF in sarcoidosis patients. Eligibility criteria include recent (2019-2024) research papers on sarcoidosis-induced heart failure, excluding other causes. The databases searched were PubMed, Google Scholar, and ScienceDirect. From 36,755 initial articles, 2,060 remained after filtering, and 17 were selected for quality assessment. Based on quality assessment, 11 studies were included in the final review. In CS, a variety of treatment strategies can be implemented. Corticosteroids are the first-line therapeutic options, and in the majority of cases, they are very successful in controlling the disease progression. Immunosuppressive agents like methotrexate and azathioprine are used to avoid long-term steroid use. Both corticosteroids and immunosuppressives act by reducing inflammation and preventing myocardial scarring. Biological agents like infliximab and adalimumab prevent disease progression by targeting specific inflammatory pathways and are used in refractory cases. Regular HF management drugs like angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), sodium-glucose transport protein 2 (SGLT2) inhibitors, beta-blockers, and diuretics help in optimizing cardiac function. In severe cases, a left ventricular assist device (LVAD) may be required. The ultimate treatment for end-stage CS is HTx, which has to be supplemented with a strong, individualized regimen of glucocorticoids and immunosuppressives to avoid graft rejection and to control sarcoidosis. Due to a lack of standard protocols for management and limited knowledge about CS, the ideal treatment of HF is still a matter of debate. Hence, further research and clinical trials need to be performed to optimize patient outcomes.

Utility of new FDG-PET/CT guidelines for diagnosing cardiac sarcoidosis in patients with implanted cardiac pacemakers for atrioventricular block

Diagnosing cardiac sarcoidosis (CS), especially in isolated cases, is challenging, particularly due to the limitations of endomyocardial biopsy, leading to potential undiagnosed cases in pacemaker-implanted patients. This study aims to provide real world findings to support new guideline for CS using 18F-fluoro-deoxyglucose positron-emission tomography computed tomography (FDG-PET/CT) which give a definite diagnosis of isolated CS (iCS) without histological findings. We examined consecutive patients with cardiac pacemakers for atrioventricular block (AV-b) attending our outpatient pacemaker clinic. The patients underwent periodical follow-up echocardiography and were divided into two groups according to echocardiographic findings: those with suspected CS and those without suspected CS. Patients suspected of having nonischemic cardiomyopathy underwent FDG-PET/CT for CS diagnosis. We investigated the utility of the new guideline for CS using FDG-PET/CT. Among the 272 patients enrolled, 97 patients were implanted with cardiac pacemakers for AV-b. Twenty-two patients were suspected of having CS during a median observation period of 5.4 years after pacemaker implantation. Of these, one did not consent, and nine of 21 cases (43%) were diagnosed with definite CS according to the new guidelines. Five of these nine patients were diagnosed with iCS using FDG-PET/CT. The number of patients diagnosed with definite CS using the new guidelines tended to be approximately 2.3 times that of the conventional criteria (p = 0.074). Three of the nine patients underwent steroid treatment. The composite outcome, comprising all-cause death, heart failure hospitalization, and a substantial reduction in left ventricular ejection fraction, were significantly lower in patients receiving steroid treatment compared to those without steroid treatment (p = 0.048). The utilization of FDG-PET/CT in accordance with the new guidelines facilitates the diagnosis of CS, including iCS, resulting in approximately 2.3 times as many diagnoses of CS compared to the conventional criteria. This guideline has the potential to support the early identification of iCS and may contribute to enhancing patient clinical outcomes.

FDG uptake patterns in isolated and systemic cardiac sarcoidosis

AIMS

We aimed to investigate the pre-treatment characteristics and treatment responses of isolated and systemic cardiac sarcoidosis (ICS and SCS) from FDG-PET/CT studies and to compare the prognoses of the two groups.

METHODS

FDG-PET/CT images taken before and after treatment of 31 ICS and 91 SCS patients were analyzed retrospectively. Treatment response and recurrence were determined from the course of FDG-PET/CT. Treatment response and the incidence of both recurrence and major adverse cardiac events (MACE) were assessed in 16 ICS and 35 SCS patients who had been treated for more than 2 years.

RESULTS

A focal uptake pattern was more often observed than a focal-on-diffuse uptake pattern in both the ICS (74.2%) and SCS (63.7%) groups. Right ventricular involvement was significantly more frequent in SCS than ICS (44.0% vs. 9.6%, p < .001). SUVmax, cardiac metabolic volume (CMV), and cardiac metabolic activity (CMA) were significantly higher in SCS than ICS (SUVmax, 9.1 ± 4.1 vs. 4.8 ± 2.1; CMV, 118.0 ± 111.3 ml vs. 68.3 ± 94.7 ml; CMA, 541.6 ± 578.7 MBq vs. 265.1 ± 396.0 MBq, p < .001). Treatment responses in the two groups were similar, and complete resolution of cardiac uptake after immunosuppressive treatment was obtained in 62.5% of ICS patients and 77.1% of SCS patients (not significantly different). Likewise, no significant difference was found in the incidence of recurrence (40.0% for ICS, 44.4% for SCS) or MACE (25.0% for ICS, 22.8% for SCS).

CONCLUSION

SCS patients had more active and extensive CS lesions than ICS patients before treatment, but the two groups showed similar treatment responses and prognoses.