People with transthyretin amyloid cardiomyopathy who have a mechanical malfunction in their heart's atrial chamber face substantially higher stroke risk, according to research to be presented at the American Heart Association's Scientific Sessions 2025. The study indicates that atrial contraction may matter as much as heart rhythm in predicting stroke risk for these patients.
Transthyretin amyloid cardiomyopathy is a progressive condition where misshapen transthyretin protein accumulates in the heart, stiffening heart walls and making it difficult for the left ventricle to relax and fill with blood. Patients face significant risk of stroke or transient ischemic attack, but until now, no tool existed to identify those at highest risk.
Researchers at the U.K. National Amyloidosis Centre analyzed health records of more than 2,300 adults with the condition between 2003 and 2023. They found approximately 1 in 8 patients with regular heart rhythm had atrial electromechanical dissociation, where the atrium appears normal on electrocardiogram but doesn't contract and pump blood effectively.
During nearly three years of follow-up, people with poor atrial contraction were more than three times as likely to experience stroke or transient ischemic attack compared to those with normal heart rhythm and normal atrial contraction. These individuals were also more likely to develop atrial fibrillation during follow-up. In the highest-risk group with poor contraction, the stroke rate reached about 9 strokes per 100 people annually.
The research team developed a risk-prediction tool using two measures widely available on echocardiograms to assess mechanical function of the atrial chamber. Stroke risk increased steadily as the atrium's ability to squeeze weakened, with the risk pattern consistent across different genetic subtypes and disease stages.
According to study author Aldostefano Porcari, consultant cardiologist at Cardiovascular Department, University of Trieste, Italy, and researcher at the National Amyloidosis Centre, University College London, this hidden dysfunction could guide earlier conversations about preventive strategies including anticoagulation medications. The findings shift attention from rhythm function to how well the atrium actually squeezes.
Fernando D. Testai, vice-chair of the American Heart Association's Brain Health Committee, noted that patients with amyloid cardiomyopathy who remain in sinus rhythm still exhibit significantly elevated stroke risk compared to the general population. He emphasized the need for novel strategies to identify high-risk individuals who may benefit from anticoagulation, even without atrial fibrillation.
However, Testai cautioned that several challenges must be addressed before this approach can be integrated into clinical practice. The diagnosis of atrial electromechanical dissociation relied on speckle-tracking strain echocardiography, a specialized imaging technique not widely accessible, and the findings require validation in larger, independent groups. Additional information about the American Heart Association's financial structure is available at https://www.heart.org/en/about-us/aha-financial-information.
The study reviewed data from one national center, so results may not apply to all people with cardiac amyloidosis. Other limitations include sometimes missing stroke classification data. The next research step involves conducting a prospective, multicenter study to investigate how the tool works and whether preventive anticoagulation can lower stroke risk in people with atrial electromechanical dissociation.
