People with transthyretin amyloid cardiomyopathy (ATTR-CM) often breathe less efficiently during physical activity, found a recent review published in Physiological Reports.
To better understand how the buildup of proteins in the heart that occurs in ATTR-CM and other forms of cardiac amyloidosis (CA) affects breathing, researchers reviewed 17 earlier studies involving more than 1,500 people with CA. All participants completed a cardiopulmonary exercise test (CPET), which measures how well the heart and lungs respond during physical effort.
The review focused on two key results from the test: VE/VCO2 slope and peak VO2. VE/VCO2 slope shows how much air someone needs to breathe to remove carbon dioxide from their body. Higher numbers mean the body is less efficient at breathing during exercise. Peak VO2 shows the highest amount of oxygen the body can use during exercise. Lower numbers mean reduced heart and lung performance.
The findings showed that people with ATTR-CM had higher VE/VCO2 slopes compared to those with another type of amyloidosis known as amyloid light-chain (AL) amyloidosis. In other words, they had to breathe more to exchange carbon dioxide for oxygen.
Read more about signs and symptoms of ATTR-CM
“Differences in exercise physiology between ATTR and AL, reflected by differences in VE/VCO2 slope, suggest distinct mechanisms that warrant further study,” said the review’s authors.
Peak VO2 was also affected, but seemed to depend more on the type of exercise test used than the type of amyloidosis. People who walked on treadmills had lower peak VO2 scores than those who used an upright cycle ergometer.
The authors believe that cardiopulmonary exercise testing could help doctors not only diagnose CA earlier, but also track how it changes over time and make better decisions about treatment.
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