Imaging cardiac innervation in amyloidosis.

Area of Science:

• Cardiology
• Nuclear Medicine
• Medical Imaging

Background:

• Cardiac amyloidosis is a restrictive cardiomyopathy causing heart failure and arrhythmias due to amyloid deposition.
• Early detection of sympathetic innervation disturbances is crucial for treatment decisions in cardiac amyloidosis.
• Cardiac sympathetic denervation is associated with a poor prognosis in this progressive disease.

Purpose of the Study:

• To evaluate the role of iodine-123 labelled metaiodobenzylguanidine ([I-123]MIBG) scintigraphy in assessing cardiac sympathetic innervation in cardiac amyloidosis.
• To determine the association between [I-123]MIBG imaging findings and prognosis in patients with cardiac amyloidosis.
• To identify specific types of cardiac amyloidosis where [I-123]MIBG imaging is most beneficial.

Main Methods:

• Utilized iodine-123 labelled metaiodobenzylguanidine ([I-123]MIBG), a norepinephrine analogue, to assess cardiac sympathetic nerve terminals.
• Analyzed planar imaging for heart-to-mediastinum ratios and wash-out rates.
• Employed single photon emission computed tomography (SPECT) for regional myocardial distribution assessment.
• Compared [I-123]MIBG utility across different types of cardiac amyloidosis (ATTR, AA, AL).

Main Results:

• Decreased heart-to-mediastinum ratios and increased [I-123]MIBG wash-out rates indicate cardiac sympathetic denervation.
• These imaging findings are linked to a poorer prognosis in cardiac amyloidosis.
• [I-123]MIBG is particularly useful for hereditary and wild-type ATTR cardiac amyloidosis, but not for AA or AL amyloidosis.

Conclusions:

• [I-123]MIBG scintigraphy is a valuable tool for evaluating cardiac sympathetic innervation in specific types of cardiac amyloidosis.
• Assessment of sympathetic denervation using [I-123]MIBG can provide prognostic information.
• Further research is needed to explore the role of positron emission tomography in cardiac sympathetic innervation assessment for amyloidosis.