Measuring levels of the protein transthyretin (TTR) in the blood may help doctors predict how well patients with transthyretin amyloid cardiomyopathy (ATTR-CM) will respond to treatment with the transthyretin stabilizer drug tafamidis. A new study suggests that serum TTR levels, measured both before and after starting therapy, can identify patients at higher risk for death or hospitalization due to heart failure.
The prospective study, published in the Journal of the American College of Cardiology (JACC), followed 169 patients as they began their treatment with tafamidis, a “stabilizer” medication that works like a protective clip to hold the TTR protein together. By keeping the protein stable, tafamidis prevents it from breaking apart and forming the harmful deposits that damage the heart muscle.
The participants in the study were mostly men, with a median age of 79. Before starting the medication, these patients were in stable condition, meaning their symptoms were under control and they had experienced no recent disease setbacks.
Researchers found that patients starting with TTR levels below 18 mg/dL faced a higher risk of death. For every 1 mg/dL increase in these starting levels, the risk of death dropped by 12%.
Additionally, the study focused on the “early increase” in TTR levels after 30 days of therapy. A rise of at least 7.5 mg/dL during the first month was associated with a lower risk of being hospitalized for heart failure.
While the early 30-day increase showed a less powerful statistical connection to the risk of death on its own, combining it with the patient’s starting TTR levels allowed researchers to more accurately identify a patient’s overall risk profile. Patients who started with higher levels (above 18 mg/dL) and also achieved a significant early rise (above 7.5 mg/dL) had the best outcomes. In fact, this specific group experienced no deaths or hospitalizations during the 24-month study period. On the other hand, patients who started with lower TTR levels and didn’t have an early increase had the highest risk, showing a 29% death rate over the two-year period.
The researchers emphasize that these findings are still exploratory. “Incorporating serial [serum TTR] measurement at baseline and 30 days after starting tafamidis could help stratify clinical severity and risk, as well as personalize care for patients with [ATTR-CM],” they wrote.
However these values are not yet a reason to change medications or switch to newer therapies on their own. Future studies with more participants will be needed to confirm these specific thresholds and better understand how TTR levels work alongside other heart tests.
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