Hidden Atrial Dysfunction Identified as Stroke Risk Factor in Heart Condition Patients

People with transthyretin amyloid cardiomyopathy who have a mechanical malfunction in the atrial chamber of their heart face significantly higher stroke risk, according to research to be presented at the American Heart Association's Scientific Sessions 2025. The study found that atrial electromechanical dissociation, where the atrium appears normal on electrocardiogram but doesn't contract effectively, more than triples the risk of stroke or transient ischemic attack even when heart rhythm appears normal.

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 with this condition face significant stroke risk, but until now, no tool existed to identify those at highest risk. The study analyzed health records of more than 2,300 adults with the condition between 2003 and 2023 from the U.K. National Amyloidosis Centre.

During nearly three years of follow-up, researchers discovered that approximately one in eight patients with regular heart rhythm had atrial electromechanical dissociation. These individuals were more than three times as likely to experience stroke or transient ischemic attack compared to people with normal heart rhythm and normal atrial contraction. They were also more likely to develop atrial fibrillation during follow-up.

"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. "Our study indicates that atrial contraction may matter as much as heart rhythm in predicting risk."

Using this data, researchers developed a risk-prediction tool that employs two measures widely available on echocardiograms to assess mechanical function of the atrial chamber. They found 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 of ATTR amyloidosis and various disease stages.

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."

The study's findings could have significant implications for clinical practice by shifting attention from rhythm function to mechanical function of the atrium. However, challenges remain before widespread implementation. The diagnosis of atrial electromechanical dissociation relied on speckle-tracking strain echocardiography, a specialized imaging technique not widely accessible. Additional information about the American Heart Association's research and resources is available at https://www.heart.org.

Researchers plan to conduct prospective, multicenter studies to investigate how the 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 decisions and help prevent disabling or fatal cerebrovascular events. The study reviewed data from one national center, so results may not apply to all people with cardiac amyloidosis, and more research is needed to determine potential treatment options.