Abstract 4365816: Unmasking Hypertrophic Cardiomyopathy: Ventricular Crypts as the Earliest Clue

Background: Left ventricular (LV) myocardial crypts, defined as blood-filled invaginations penetrating >50% of myocardial thickness, remain a debated imaging finding. While associated with hypertrophic cardiomyopathy (HCM) in genotype-positive/phenotype-negative individuals, their prognostic significance in asymptomatic patients without confirmed genetic mutations is unclear. Case Presentation: A 20-year-old asymptomatic female with inferoseptal precordial T-wave inversions underwent sports pre-participation screening. Transthoracic echocardiography (TTE) revealed an apical LV crypt without hypertrophy. Cardiac MRI (CMR) demonstrated non-specific late gadolinium enhancement (LGE) in the basilar septum and inferior walls but no hypertrophy. Exercise stress testing and ambulatory monitoring were normal, and no activity restrictions were imposed. Repeat CMR at 2 years revealed new apical hypertrophy (12 mm) with apical to basal ratio of 1.2 raising suspicion for apical hypertrophy. Discussion: This case challenges conventional paradigms by demonstrating temporal progression from isolated crypts to hypertrophy in a genotype-negative patient, supporting emerging evidence that crypts may represent a "pre-hypertrophic" marker. The presence of non-specific LGE on initial CMR, a pattern linked to early fibrosis in HCM mutation carriers, raises questions about whether such findings in crypt-bearing myocardium warrant closer surveillance. Current guidelines lack consensus on imaging intervals for crypts without hypertrophy; this rapid phenotypic evolution within 2 years—faster than typical HCM trajectories—suggests current 3–5 year surveillance windows may be inadequate. The case compels re-examination of crypt management in asymptomatic populations, particularly athletes, where delayed diagnosis carries sudden cardiac death risks. It advocates for reclassifying crypts with LGE as high-risk morphological markers and underscores the need for prospective studies to define optimal surveillance protocols.