A Stepwise Multimodality Imaging Approach to Out-of-Hospital Cardiac Arrest in Cystic Fibrosis.

Out-of-hospital cardiac arrest (OHCA) without ST-segment elevation represents a challenging diagnostic scenario, particularly in young patients with low pretest probability of atherosclerotic disease. We report the case of a 25-year-old man with cystic fibrosis who presented with ventricular fibrillation during a pulmonary exacerbation complicated by hemoptysis and hypoxemia. After successful resuscitation, electrocardiography showed anterolateral T-wave inversions and high-sensitivity troponin demonstrated a marked rise and fall. Transthoracic echocardiography revealed regional wall motion abnormalities with mildly reduced left ventricular ejection fraction. In the absence of ST-segment elevation, coronary computed tomography angiography was performed and excluded obstructive coronary artery disease and congenital anomalies. Early cardiac magnetic resonance demonstrated extensive transmural late gadolinium enhancement in a coronary distribution with microvascular obstruction, consistent with acute ischemic myocardial infarction despite normal epicardial coronaries, establishing a diagnosis of myocardial infarction with nonobstructive coronary arteries (MINOCA). This case illustrates a structured, stepwise, and entirely noninvasive multimodality imaging approach to OHCA without ST-elevation and highlights the central role of early cardiac magnetic resonance in mechanism clarification and clinical decision-making in suspected MINOCA.