Impaired retention of technetium-99m tetrofosmin in hypertrophic cardiomyopathy

Area of Science:

• Cardiology
• Nuclear Medicine
• Biomedical Imaging

Background:

• Hypertrophic cardiomyopathy (HC) is a complex cardiac condition.
• Noninvasive assessment of myocardial damage in HC is crucial for diagnosis and management.
• Technetium-99m tetrofosmin is a radiotracer used in myocardial perfusion imaging.

Purpose of the Study:

• To evaluate the utility of technetium-99m tetrofosmin myocardial imaging for detecting myocardial damage in various forms of HC.
• To differentiate between apical HC, asymmetric septal HC (ASH), and dilated cardiomyopathy (DC)-like presentations.

Main Methods:

• Single-photon emission computed tomographic (SPECT) imaging was performed using technetium-99m tetrofosmin.
• Patients included those with apical HC, ASH, DC-like cardiomyopathy, and healthy controls.
• Myocardial damage was assessed using a bull's-eye map, quantifying the total defect score and washout rate in left ventricular segments.

Main Results:

• Apical HC showed localized increases in defect score and washout rate in hypertrophied regions.
• ASH patients exhibited an increased washout rate across the entire left ventricle, indicating impaired mitochondrial tetrofosmin retention.
• The DC-like group demonstrated further increased washout rates compared to the ASH group.

Conclusions:

• Technetium-99m tetrofosmin SPECT imaging can noninvasively identify myocardial damage in HC.
• Myocardial cell dysfunction is localized to hypertrophied regions in apical HC.
• Widespread mitochondrial tetrofosmin retention impairment is observed in ASH and is more pronounced in DC-like cardiomyopathy.