Imaging data collected by advanced cardiac magnetic resonance (CMR) can significantly improve the diagnosis of cardiac sarcoidosis and accurately predict the risk of future life-threatening cardiac events, a study found.
The study, “Complementary Role of CMR to Conventional Screening in the Diagnosis and Prognosis of Cardiac Sarcoidosis,” was published in the journal JACC: Cardiovascular Imaging.
Cardiac sarcoidosis is a rare condition thought to affect only about 5-10% of patients with sarcoidosis. However, autopsy studies have found that it actually may be more prevalent than believed.
A recent nationwide study in the U.S. found that the number of cardiac sarcoidosis cases doubled from 2005 to 2011. This may be due to improved awareness and advanced imaging diagnostic tools, but it also suggests that this condition may not be that rare.
The use of imaging techniques such as CMR and positron emission tomography (PET) has led to improved diagnoses of cardiac sarcoidosis. However, these methods are expensive, which limits their availability for practical screening and early diagnosis.
“In the absence of a gold standard test and given the low sensitivity and invasive nature of endomyocardial biopsy, the diagnosis of cardiac sarcoidosis is mainly based on a constellation of symptoms and specific findings from noninvasive diagnostic modalities,” the researchers wrote.
Researchers evaluated various methods of diagnosing cardiac sarcoidosis in 321 patients whose condition was confirmed by biopsies. Participants were enrolled in the study from October 2006 to June 2013 and followed up through May 2015.
All participants underwent conventional cardiac testing, including an analysis of cardiac symptoms, electrocardiography (ECG), Holter monitoring, and transthoracic echocardiogram (TTE). Participants also were evaluated with CMR.
At baseline, 29.9% of patients were diagnosed with cardiac sarcoidosis based on consensus criteria from the Heart Rhythm Society. Using criteria from the Japanese Ministry of Health and Welfare, only 8.7% of patients were diagnosed.
The team found that CMR was the most sensitive and specific diagnostic test. It was able to detect cardiac sarcoidosis in 44 patients with cardiac symptoms and ECG abnormalities, as well as in 15 asymptomatic patients who had normal baseline test results. Overall, CMR could help increase the accuracy of diagnosis and prognosis, the research team stated.
TTE was able to predict 83.9% of the cardiac sarcoidosis cases, but its diagnostic sensitivity was only 27.1%, the lowest among the tested methods.
Analysis of CMR images with late gadolinium enhancement (LGE), which provides a measure of tissue scarring, revealed that accumulation of LGE was associated with a poorer prognosis.
The presence of scarred tissue in the heart was found to increase the risk of all-cause mortality, life-threatening arrhythmia, unplanned hospitalization for heart failure, or cardiac transplantation by a factor of 5.68.
“Of all cardiac tests, CMR was the most valuable in the diagnosis and prognosis of cardiac sarcoidosis in a general sarcoidosis population,” the researchers concluded.
The team believes that CMR “should be an integral part of the diagnostic strategy, especially in patients with cardiac symptoms and/or abnormal ECG.”