People with transthyretin amyloid cardiomyopathy who experience atrial electromechanical dissociation face more than triple the risk of stroke or transient ischemic attack compared to those with normal heart rhythm and effective atrial contraction, according to research to be presented at the American Heart Association's Scientific Sessions 2025. 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, revealing that approximately one in eight patients with regular heart rhythm had this mechanical dysfunction where the atrium appears normal on electrocardiogram but doesn't contract effectively.
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. During nearly three years of follow-up, individuals with atrial electromechanical dissociation showed dramatically increased stroke risk and were more likely to develop atrial fibrillation, another known stroke risk factor. The highest-risk group experienced about nine strokes per 100 people annually, highlighting the significant danger even when patients maintain regular heart rhythm.
"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. The tool showed that stroke risk increased steadily as the atrium's ability to squeeze weakened, with the risk pattern remaining 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." However, Testai cautioned that the diagnosis of atrial electromechanical dissociation relied on speckle-tracking strain echocardiography, a specialized imaging technique not widely accessible. The study's findings could potentially guide earlier conversations about preventive strategies including anticoagulation medications, with researchers planning 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.
