Hidden Atrial Dysfunction Identified as Stroke Risk Factor in Heart Muscle Disease Patients
A new study reveals that people with transthyretin amyloid cardiomyopathy face significantly higher stroke risk when they have atrial electromechanical dysfunction, and researchers have developed a noninvasive assessment tool to identify those who might benefit from preventive treatments.
People with transthyretin amyloid cardiomyopathy who have a mechanical malfunction in their heart's atrial chamber face substantially higher stroke risk, according to preliminary research to be presented at the American Heart Association's Scientific Sessions 2025. The study found that individuals with this hidden dysfunction were more than three times as likely to experience stroke or transient ischemic attack compared to those with normal atrial contraction.
Transthyretin amyloid cardiomyopathy is a progressive condition where misshapen 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 stroke risk even when their heart rhythm appears normal, and until now, no tool existed to identify those at highest risk. "Even with a regular heart rhythm, some people with transthyretin amyloid cardiomyopathy are still at risk of stroke if their atrium doesn't squeeze well," said study author Aldostefano Porcari, M.D., Ph.D., consultant cardiologist at Cardiovascular Department, University of Trieste, Italy.
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 that approximately one in eight 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, these individuals showed dramatically increased stroke risk and were more likely to develop atrial fibrillation.
Using this data, researchers developed a risk-prediction tool that employs two measures widely available on echocardiograms to assess the mechanical function of the atrial chamber. Stroke risk increased steadily as the atrium's ability to squeeze weakened, with the highest-risk group experiencing about nine strokes per 100 people annually. The risk pattern remained consistent across different genetic subtypes and disease stages, suggesting atrial dysfunction represents a common driver of stroke risk in this condition. More information about the research methodology is available at https://www.heart.org.
Fernando D. Testai, M.D., Ph.D., FAHA, vice-chair of the American Heart Association's Brain Health Committee, noted that "patients with amyloid cardiomyopathy who remain in sinus rhythm still exhibit a significantly elevated stroke risk compared to the general population, so there is a need for novel strategies to identify high-risk individuals who may benefit from anticoagulation, even in the absence of atrial fibrillation." However, he cautioned that diagnosis currently relies on speckle-tracking strain echocardiography, a specialized imaging technique not widely accessible.
The study's findings shift attention from rhythm function to mechanical performance of the heart's chambers. Researchers plan to conduct prospective, multicenter studies to investigate how the assessment tool works and whether preventive anticoagulation can lower stroke risk in people with atrial electromechanical dissociation. The goal is to generate practice-ready evidence that can guide individualized treatment decisions and help prevent disabling or fatal cerebrovascular events in this vulnerable patient population.