Trapped in the Trabeculae: A Rare Case of Noncompaction Cardiomyopathy and Large Left Ventricular Thrombus

Left ventricular noncompaction (LVNC) is a rare primary cardiomyopathy characterized by a failure of myocardial morphogenesis, resulting in a prominent, characteristic "sponge-like" trabeculated endocardial layer. Clinical presentation is classical for heart failure, ventricular arrhythmias, and systemic thromboembolism, which defines its severity. Here, we describe a 34-year-old male with no prior medical history who presented with progressive dyspnea and volume overload. On initial evaluation, severe biventricular failure, stage 3b chronic kidney disease (type 2 cardiorenal syndrome), and significant hemodynamic impairment were noted. Subsequently, contrast-enhanced transthoracic echocardiography (TTE) was consistent with the diagnosis of LVNC and identified multiple mural thrombi, including a 2 cm mobile apical thrombus. Coronary angiography revealed normal coronary anatomy. Following these findings, the patient was stabilized with intravenous diuretics and initiated on guideline-directed medical therapy (GDMT). Due to the high risk of sudden cardiac death and persistent low ejection fraction, he was discharged with a wearable cardioverter defibrillator and referred for advanced heart failure and transplant evaluation. Shifting focus to the underlying pathophysiology, thrombus formation in LVNC is unique. It goes beyond global systolic dysfunction; the deep intertrabecular recesses create stasis that predisposes to fibrin deposition regardless of wall motion. This thrombogenicity necessitates a nuanced approach to anticoagulation. In summary, LVNC should be a primary consideration in young patients presenting with new-onset heart failure. This case underscores the necessity of imaging to identify obscured thrombi and highlights the evolving role of direct oral anticoagulants (DOACs) in managing the specific mechanical risks inherent to noncompacted myocardium.