A Rare Presentation of Left Ventricular Noncompaction Cardiomyopathy Revealed by Acute Decompensated Heart Failure.

Left ventricular noncompaction (LVNC) is an uncommon genetic cardiomyopathy characterized by excessive trabeculations resulting from incomplete myocardial compaction and may remain clinically silent until adulthood. We report the case of a 62-year-old woman with no prior cardiovascular disease who presented with progressive dyspnea, orthopnea, lower extremity edema, and new-onset rapid atrial fibrillation, resulting in acute decompensated heart failure. Initial evaluation revealed elevated blood pressure, irregularly irregular rhythm, pulmonary crackles, and lower limb edema. Transthoracic echocardiography demonstrated a left ventricular ejection fraction of approximately 25%, diffuse hypokinesis, and a distinct two-layered myocardium with prominent apical and lateral trabeculations consistent with LVNC. Coronary angiography ruled out obstructive coronary artery disease, and transesophageal echocardiography confirmed severe systolic dysfunction without atrial thrombus before successful cardioversion. The patient improved with intravenous loop diuretics, initiation of guideline-directed medical therapy, and anticoagulation due to her atrial fibrillation and reduced ejection fraction. This case highlights an uncommon presentation of previously unrecognized LVNC diagnosed in the setting of acute heart failure triggered by arrhythmia, underscoring the importance of echocardiography in differentiating cardiomyopathy phenotypes. Early recognition is essential, as LVNC carries increased risks of arrhythmias, thromboembolic events, and progressive heart failure. Clinicians should maintain a high index of suspicion for LVNC in adults presenting with unexplained systolic dysfunction and excessive trabeculation on imaging, particularly when accompanied by atrial fibrillation.