Objective: Early diagnosis of severe inflammatory forms of non-ischaemic cardiomyopathy (NICM), e.g. cardiac sarcoidosis (CS) or giant cell myocarditis (GCM), may enable unique treatment. However, there is limited information on how to identify CS or GCM in unselected patients with suspected NICM. We studied the clinical and imaging predictors of severe cardiac inflammation at the era of late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR).
Methods and results: In this observational cohort study, we enrolled 86 consecutive patients referred for LGE-CMR due to suspected NICM. Patients were extensively examined for underlying aetiology and followed up for at least two years to assure the final diagnosis. Ischaemic cardiomyopathy was excluded. During follow-up, 11(13%) patients were diagnosed with CS (n = 8) or GCM (n = 3). At baseline, sustained ventriculartachycardia (OR = 20.8, P = 0.001) and the volume of left ventricular LGE (OR = 1.06 for each 1% increase in LGE, P = 0.001) were significant adjusted predictors of CS or GCM. Palpitation, a disease course less than 3 months, septal abnormality in echocardiography, reduced stroke volume and atrioventricular block were other unadjusted predictors of CS or GCM. Multifocal LGE, affecting several myocardial layers and not confined to coronary artery perfusion territories, was useful in identifying CS or GCM, with 52-fold unadjusted OR (P < 0.001), sensitivity of 91% and specificity of 84%. In addition, positron emission tomography detected mediastinal lymph node biopsy targets in CS.
Conclusions: In consecutive patients suspected for NICM, LGE volume and sustained ventricular tachycardia predict independently CS or GCM. Multifocal LGE is useful in identifying severe cardiac inflammation.