Key result
Endomyocardial biopsy confirms rare apolipoprotein A-IV cardiac amyloidosis mimicking hypertrophic cardiomyopathy.
Why the study?
Apolipoprotein A-IV amyloidosis is a rare systemic amyloidosis that can involve the heart and mimic hypertrophic cardiomyopathy, requiring clarification of its clinical presentation and diagnostic challenges.
Case Report (n=1)
Apolipoprotein A-IV cardiac amyloidosis is a rare, slow-progressing infiltrative disease that can cause massive ventricular wall thickening mimicking hypertrophic cardiomyopathy, emphasizing the critical role of endomyocardial biopsy when noninvasive imaging is discordant.
May warrant biopsy in imaging-discordant suspected hypertrophic cardiomyopathy; leaves open the full phenotypic spectrum of apolipoprotein A-IV amyloidosis.
BACKGROUND: Apolipoprotein A-IV amyloidosis (AApoAIV) is a rare systemic amyloidosis that can involve the heart and mimic hypertrophic cardiomyopathy. CASE SUMMARY: A 64-year-old woman with presumed hypertrophic cardiomyopathy presented with dyspnea. Imaging showed severe left ventricular wall thickening, outflow tract obstruction, and systolic anterior motion of the mitral valve. Multimodality evaluation suggested infiltrative cardiomyopathy including diffuse late gadolinium enhancement, abnormal nulling, elevated T1 on cardiac magnetic resonance, and an apical-sparing strain pattern on echocardiography. Technetium-99m pyrophosphate scintigraphy demonstrated no myocardial uptake. Endomyocardial biopsy confirmed AApoAIV deposition. DISCUSSION: AApoAIV cardiac amyloidosis may present with massive left ventricular wall thickening. Discordant noninvasive testing may occur, and endomyocardial biopsy remains essential for diagnosis. TAKE-HOME MESSAGES: AApoAIV cardiac amyloidosis is a rare infiltrative cardiomyopathy that may mimic hypertrophic cardiomyopathy and follow an indolent course, allowing myocardial infiltration over years. Negative technetium-99m pyrophosphate scintigraphy does not exclude amyloidosis, particularly in non-transthyretin amyloid subtypes like AApoAIV, and tissue diagnosis is required.
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Coderre et al. (2026) conducted a case report in Apolipoprotein A-IV Cardiac Amyloidosis (n=1). Apolipoprotein A-IV cardiac amyloidosis was evaluated on Pathological diagnosis via endomyocardial biopsy. Endomyocardial biopsy confirmed apolipoprotein A-IV cardiac amyloidosis in a patient presenting with massive left ventricular wall thickening that mimicked hypertrophic cardiomyopathy despite discordant noninvasive imaging.
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