New Biomarkers Predict Adverse Events in Cardiac Sarcoidosis

Matthew Aitken, MBChB

Results from an investigation on the prognostic value of Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) revealed an imaging feature that was common among patients with cardiac sarcoidosis.¹

The presence of left and right ventricular late gadolinium enhancement (LGE) on cardiac MRI scans, along with elevated fluorodeoxyglucose (FDG) uptake on PET scans, were both strong indicators of increased risk for major adverse cardiac events (MACE) in patients with cardiac sarcoidosis.

The fact that both imaging biomarkers were predictive of MACE highlights the importance of both inflammation and fibrosis in the progression of cardiac sarcoidosis, Matthew Aitken, Department of Medical Imaging, Toronto General Hospital, University Health Network, University of Toronto, and investigators emphasized in the article.

Diagnosis of cardiac sarcoidosis can be challenging, as there are no specific symptoms or diagnostic tests, according to the study. Late gadolinium enhancement at cardiac MRI and fluorodeoxyglucose uptake at PET have emerged as potential imaging biomarkers for cardiac sarcoidosis.

MRI, PET as Predictors of MACE in Cardiac Sarcoidosis

Late gadolinium enhancement at MRI was found to be a stronger predictor than fluorodeoxyglucose uptake at PET. This may reflect differences in the underlying pathophysiology of the disease. Late gadolinium enhancement is expected to reflect fibrosis and scarring, whereas fluorodeoxyglucose uptake reflects inflammation.

The meta-analysis showed the odds ratio (OR) for MACE was 8.0 (95% confidence interval [CI]: 4.3 to 15.0) for late gadolinium enhancement and 2.1 (95% CI: 1.4 to 3.2) for fluorodeoxyglucose uptake. However, LGE was a stronger predictor of MACE than fluorodeoxyglucose uptake.

When the team compared MRI and PET directly, late gadolinium enhancement remained a significant predictor of MACE (OR, 10.4 [95% CI: 3.5 to 30.5]; P < .001), whereas fluorodeoxyglucose uptake was not (OR, 1.9 [95% CI: 0.82 to 4.4]; P = .13).

Scanning for Fibrosis and Inflammation

Investigators performed a systematic review of the literature to identify studies that evaluated the prognostic value of cardiac MRI or FDG PET in adults with cardiac sarcoidosis. The search included 6 databases from inception until January 2022 with the team identifying 37 studies that met their inclusion criteria, comprising a total of 3489 patients with a mean follow-up of 3.1 years.

The primary outcome of major adverse cardiac events was assessed as a composite including death, ventricular arrhythmia, and heart failure hospitalization.

There were few studies directly comparing MRI and PET in the same patients, which limited the ability to draw firm conclusions about the relative prognostic value of the 2 imaging modalities, investigators noted as a limitation. Additionally, they wrote that many of the included studies were at risk for bias, which could affect the reliability of the results.

However, despite theses limitations investigators highlighted the important insight the data provided into the prognostic value of imaging biomarkers in cardiac sarcoidosis, which may help guide clinical decision-making in the management of this challenging disease.

References:

1. Aitken, M., Davidson, M., Chan, M. V., Urzua Fresno, C., Vasquez, L. I., Huo, Y. R., McAllister, B. J., Broncano, J., Thavendiranathan, P., McInnes, M. D., Iwanochko, M. R., Balter, M., Moayedi, Y., Farrell, A., & Hanneman, K. (2023). Prognostic value of cardiac MRI and FDG PET in cardiac sarcoidosis: A systematic review and meta-analysis. Radiology. https://doi.org/10.1148/radiol.222483