The Role of Native T1 Mapping in the Diagnosis of Myocarditis in a Real-World Setting.

BACKGROUND: This prospective single-center study sought to investigate the impact of cardiovascular magnetic resonance (CMR) on the diagnosis of myocarditis, with special attention given to absolute T1 values and defined cutoff values.
METHODS: All patients referred to our center with the suspicion of an inflammatory myocardial disease were diagnosed by a consensus expert consortium blinded to CMR findings. Classical Lake Louise criteria were then used to confirm or change the diagnosis.
RESULTS: Of a total of 149 patients, 15 were diagnosed with acute myocarditis without taking CMR findings into account. Acute myocarditis was excluded in 91 patients, whereas 42 cases were unclear. Using classical Lake Louise criteria, an additional 35 clear diagnoses were made, either confirming or excluding myocarditis. In the remaining patients, there was no further increase in definitive diagnoses using T1 measurements. The diagnostic performance of T1 mapping in distinguishing acute myocarditis patients from healthy controls was good (area under the curve (AUC) 0.835, cutoff value 1019 ms, sensitivity 73.7%, specificity 72.4%). In the group of patients with suspected and then excluded myocarditis, the cutoff value had a false-positive rate of 56.6%.
CONCLUSIONS: Acute myocarditis should be diagnosed on the basis of clinical and imaging factors, whereas T1 mapping could be helpful, especially for excluding acute myocarditis.