Active clinically isolated cardiac sarcoidosis with inactive pulmonary sequelae: incremental diagnostic value of multimodality imaging: a case report.

BACKGROUND: Cardiac sarcoidosis remains a major diagnostic challenge when myocardial inflammation occurs in the absence of clinically active extracardiac disease. In this setting, non-invasive tissue characterization and metabolic imaging may provide critical incremental value over conventional structural assessment. CASE SUMMARY: A 62-year-old woman with progressive exertional dyspnoea and long-standing ventricular ectopy underwent multimodality evaluation. Echocardiography showed mild biventricular systolic dysfunction, reduced global longitudinal strain, and focal basal-to-mid septal abnormalities. Coronary computed tomography (CT) angiography excluded obstructive coronary artery disease and showed inactive pulmonary granulomatous sequelae. Cardiac magnetic resonance demonstrated mild-to-moderate biventricular dysfunction and patchy non-ischaemic late gadolinium enhancement in the basal-to-mid septum with elevated native T1 values but no T2 evidence of oedema. 18F-fluorodeoxyglucose positron emission tomography/CT subsequently revealed focal and multifocal myocardial uptake on a suppressed background, confirming active myocardial inflammation without extracardiac hypermetabolic disease. Immunosuppressive therapy was initiated, and guideline-directed heart failure therapy was optimized. DISCUSSION: This case illustrates how stepwise multimodality imaging can establish the diagnosis of active cardiac sarcoidosis, provide precise non-invasive tissue characterization, distinguish active inflammation from fibrosis, and directly guide immunosuppressive treatment when extracardiac disease is clinically silent.