Amyloid Scan of the Heart as Major Predictor of Cardiac Events
French researchers at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2015 annual meeting have proposed that scanning of heart for amyloid buildup can help diagnose cardiac disorders during initial stages and can be helpful in timely intervention. Amyloid is a lipid substance whose accumulation in various organs of the body (known as amyloidosis) can put the patient at high risk for cardiovascular diseases. Other health disorders like stroke and Alzheimer’s disease have also been found in relation to it.
The deposition of amyloid is thought to be due to overexpression of the TTR (transthyretin-type) gene. It commonly deposits in the blood vessels as plaque and gives rise to conditions like hypertension, cardiomegaly (enlargement of heart), abnormal cardiac sounds, coronary heart disease (CHD) and even heart failure. Assessment of the amount of amyloid deposition within and around the heart can give an idea about the degree of heart damage and can help in establishing the prognosis.
Technetium-99m hydroxymethylene diphosphonate (Tc-99m HMDP) is a radiotracer that is commonly employed for amyloid scanning. A study was conducted to evaluate the cardiac condition in patients with TTR amyloidosis in which 55 out of 121 patients underwent the Tc-99m HMDP myocardial scintigraphy. 21 were diagnosed to have wild-type transthyretin (wt-TTR) cardiac amyloidosis and 26 had mutated transthyretin (m-TTR) cardiac amyloidosis.
The results validated the efficacy of amyloid scanning in picking up cardiac disorders. Further studies are underway and it won’t be long before amyloid scans will become the standard protocol for the monitoring of patients with cardiac amyloidosis.