Idiopathic dilated cardiomyopathy diagnosed by cardiac magnetic resonance imaging in a patient with new-onset heart failure: a case report

Idiopathic dilated cardiomyopathy (IDCM) is a myocardial disease characterized by ventricular dilation and systolic dysfunction in the absence of coronary artery disease, arterial hypertension, valvular heart disease, or congenital heart defects. Identifying its etiology poses a diagnostic challenge, and cardiac magnetic resonance (CMR) is a highly useful tool. We present the case of a 43-year-old woman with a history of bronchial asthma and overweight status who presented with progressive dyspnea, exercise intolerance, and clinical signs of congestive heart failure. The electrocardiogram showed sinus rhythm with complete left bundle branch block, while the echocardiogram revealed dilation of all four cardiac chambers and a left ventricular ejection fraction of 35%, with no segmental wall motion abnormalities. Coronary angiography was normal. CMR demonstrated a pattern of linear mid-wall late gadolinium enhancement in the interventricular septum, a characteristic finding of non-ischemic dilated cardiomyopathy consistent with IDCM. The patient showed a favorable clinical course following the initiation of medical therapy. Follow-up plans included Holter monitoring, assessment for primary prevention of sudden cardiac death via an implantable cardioverter-defibrillator, and clinical evaluation of first-degree relatives. This case highlights the incremental value of CMR in the etiological diagnosis of dilated cardiomyopathy, particularly after coronary artery disease has been ruled out. Characterizing the fibrosis pattern via late gadolinium enhancement improves diagnostic accuracy, provides relevant prognostic information, and guides therapeutic decisions as well as family screening in patients with suspected idiopathic or genetic disease.