Cardiac amyloidosis is caused by the deposition of proteins in the heart. The protein deposits can also occur in the other organs, leading to life-threatening organ failure.
‘The blood test detects the levels of vitamin-A transport protein retinol-binding protein 4 (RBP4) to identify patients with transthyretin cardiac amyloidosis (ATTR), which is an under-recognized cause of heart failure.’
ATTR amyloidosis is a form of cardiac amyloidosis which occurs due to the misfolded protein transthyretin. ATTR amyloidosis is more common in older adults and can occur from a genetic mutation that causes the TTR protein to become unstable, misfold, and then build up in the heart. The most common genetic mutation that causes ATTR amyloidosis is seen in approximately 3.5 percent of African Americans. Amyloid deposition can cause electrical abnormalities and decrease the heart's ability to relax and contract, leading to congestive heart failure.
In most of the patients, amyloidosis is unrecognized. Diagnosis of ATTR amyloidosis can be challenging for doctors. Recent studies have suggested that as many as 10 percent of the older patients with certain types of congestive heart failure may have cardiac amyloidosis.
A research team led by Frederick L. Ruberg, MD, director of advanced imaging at Boston Medical Center and associate professor of medicine at Boston University School of Medicine, looked out for ways to develop new testing strategies to improve diagnosis.
A specific blood protein called retinol-binding protein 4 (RBP4)
was identified by the research team. RBP4 was used to determine the likelihood of ATTR amyloidosis in a patient with congestive heart failure.
In addition, in work guided by Marios Arvanitis, MD, an internal medicine resident at BMC, the research team developed a mathematical calculator that incorporates RBP4 and other commonly ordered clinical tests that can be used to estimate the probability of ATTR amyloidosis in a given patient. An important advantage of this algorithm is that it can be used in the context of a doctor's office visit at the point-of-care.
This discovery could guide clinical decision making and increase recognition of this disease. Since many new drug therapies are in various stages of development now for ATTR amyloidosis, recognition and accurate diagnosis is essential to get a patient on the correct treatment.
"Given that new targeted pharmacologic therapies are being developed that specifically treat ATTR, identifying patients with this disease and providing an early and accurate diagnosis is crucial to treatment," explained Ruberg, the study's corresponding author.
Ruberg believes there is also potential for this blood test or the entire algorithm to be used in ATTR cardiac amyloidosis monitoring as a marker of disease progression and prognosis.
The findings appear in the journal JAMA Cardiology.