Scientists have created a simple blood test to find out who is most at risk from hypertrophic cardiomyopathy (HCM), the world’s most common inherited heart condition. HCM causes the heart wall to thicken and is passed down through families. Some patients show few symptoms, while others face serious complications like heart failure or cardiac arrest. Doctors until now have struggled to predict which patients will have dangerous problems. A team from Harvard and Oxford measured a protein called N-terminal Pro-B-type natriuretic peptide (NT-Pro-BNP) in 700 HCM patients. This protein is released when the heart is under strain. High NT-Pro-BNP levels showed poorer heart blood flow, more scarring, and risks of abnormal rhythms like atrial fibrillation. Prof Carolyn Ho, lead researcher and medical director at Harvard, said the test could "target the right therapies to the right patients at the right time." She added, "People with the highest risk could be targeted for potentially life-saving treatments... while those at lowest risk could avoid unnecessary treatment." Lara Johnson from Southampton was diagnosed with HCM after struggling with breathlessness. She said, "A simple blood test, which could help identify future risks earlier, would take away so much of that anxiety." For her and many others, the test offers hope for better control and peace of mind. Prof Bryan Williams of the British Heart Foundation, which funded the study, said the test "could benefit patients around the world" by predicting heart function and future risks. He noted it may also lead to new treatments to reduce HCM risks. This blood test could transform care for millions living with this genetic heart disease by improving early detection and treatment decisions.