Abstract Body (Do not enter title and authors here): Background and Aims:

Cardiac sarcoidosis is a potentially life-threatening condition that requires a timely and accurate diagnosis. However, current diagnostic schemes lack validation. We aimed to validate the 2014 Heart Rhythm Society (HRS) and 2016 Japanese Circulation Society (JCS) diagnostic schemes and compare their performance with cardiovascular magnetic resonance imaging (CMR) phenotyping.

Methods:

We studied a multicenter cohort of consecutive patients with histology-supported sarcoidosis and suspected cardiac involvement evaluated by CMR. We validated the 2014 HRS and 2016 JCS schemes for “clinical diagnosis” and CMR phenotyping against cardiac histology as the reference standard in patients with cardiac histology-supported cardiac sarcoidosis and against major adverse cardiac events (MACE) in those with only extracardiac histology-supported sarcoidosis. We validated the diagnostic strategies against MACE using time-dependent receiver operating characteristic analysis, accounting for competing risks.

Results:

Among 32 patients with a cardiac histology-supported diagnosis, the 2014 HRS, 2016 JCS, and CMR phenotyping strategies demonstrated high sensitivity at 100%, 96.9%, and 100%, respectively. Among 1,600 patients with only extracardiac histology-supported sarcoidosis, the same strategies diagnosed cardiac sarcoidosis in 37.4%, 22.7%, and 19.4%, respectively. The 2014 HRS scheme had high sensitivity but low specificity, whereas the 2016 JCS scheme and CMR phenotyping provided better balance. The time-dependent area under the curve (AUC) for MACE at 1 year was higher for the 2016 JCS scheme (0.855) and CMR phenotyping (0.853) than for the 2014 HRS scheme (0.805). AUCs did not differ among strategies at 5 and 10 years.

Conclusions:

Compared with the 2014 HRS and 2016 JCS schemes, CMR phenotyping offers advantages, including simplicity, a lower risk of overdiagnosis, and validation results superior to those of the 2014 HRS scheme and comparable to those of the 2016 JCS scheme, making a compelling case for its use as a diagnostic strategy for cardiac sarcoidosis.