More than half of adults under the age of 70 have silent artery plaque that shows no symptoms, according to a major new study presented at the European Society of Cardiology congress in Munich.

The REACT study, published in the New England Journal of Medicine, examined 16,808 adults aged 18 to 70 across Denmark and Spain. It found that 57.1 per cent had silent atherosclerosis, Fox News reported.

Strikingly, about one in thirteen adults under 30 already had artery plaque, while nearly nine in ten people aged 60 to 70 were affected. Plaque appeared in men roughly five to ten years earlier than in women, according to Medscape.

Dr. Borja Ibáñez of the Spanish National Cardiovascular Research Centre said the findings change how early cardiovascular disease can be detected. For the first time, doctors can directly identify the disease itself, before heart attacks and strokes occur.

The study adds to growing evidence that cardiovascular prevention should begin decades earlier than current guidelines typically recommend.