Learn The BasicsTransthyretin amyloid cardiomyopathy (ATTR-CM) is a rare and progressive heart disease characterized by misfolded amyloid fibrils accumulating in the heart muscle and causing damage. The disease can be hereditary, when it is caused by a mutation in the TTR gene, or it can develop as a result of the normal aging process (wild-type ATTR-CM).
Researchers have developed two staging systems for ATTR-CM based on different biological measurements known as biomarkers.
One of these staging systems uses levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and estimated glomerular filtration rate (eGFR) as biomarkers to classify the stage of disease. The other uses levels of NT-proBNP and cardiac troponin (cTnT), an early biomarker of heart muscle injury, to stage the disease. The second system is only valid for patients with wild-type ATTR-CM.
With the first staging system, threshold levels of NT-proBNP should be below 3000 ng per liter, and the threshold eGFR should be more than 45 milliliters per minute.
Learn about the causes and risk factors of ATTR-CM
The second staging system defines the threshold of normal NT-proBNP levels as 3000 ng per liter and the threshold of cTnT as 0.05 ng per milliliter.
According to both staging systems, patients with levels of both biomarkers below the threshold are considered to have Stage 1 disease. Those with one biomarker below the threshold and one above are considered to have Stage 2 disease. Those with levels of both biomarkers above the threshold are considered to have Stage 3 disease, the most serious type.
Survival rates
With the first staging system, the median survival of patients with Stage 1 ATTR-CM is 5.8 years after diagnosis. The median survival of patients with Stage 2 disease is 3.9 years after diagnosis, and that of patients with Stage 3 disease is 2 years from the time of diagnosis.
According to the second staging system, the four-year overall survival rate of patients with Stage 1 disease is 57%. That of patients with Stage 2 disease is 42%, while that of patients with Stage 3 disease is only 18%.
A French study conducted between 2011 and 2019 calculated the median survival of patients with ATTR-CM as being 3.5 years from the time of diagnosis. The authors of the study also reported an increase in the incidence of the disease over the study period, which suggests that the diagnosis of the disease has improved in recent years.
Lifestyle changes
Lifestyle changes that could improve prognosis in ATTR-CM are the same as those that can be adopted to manage congestive heart failure.
These include:
- Keeping a healthy weight
- Quitting smoking
- Doing moderate physical exercise
- Resting adequately
- Managing stress
- Limiting liquid intake
- Avoiding or limiting alcohol
- Monitoring your blood pressure
- Avoiding infections.
Reviewed by Harshi Dhingra, M.D., on Nov. 11, 2024.