Prevalence of Subclinical Coronary Artery Atherosclerosis in the General Population

This Swedish study (SCAPIS) did something rarely attempted at scale: it took more than 25,000 randomly selected middle-aged people from the general population — not patients — and looked directly inside their coronary arteries with CT angiography.

What it found is sobering and clarifying. Silent coronary atherosclerosis was present in 42 percent of these symptom-free adults; significant narrowing in about 5 percent. Disease clustered in the proximal left anterior descending artery and appeared roughly a decade later in women than men. The calcium score tracked closely with disease — every person with a calcium score above 400 had atherosclerosis — but the study also exposed the limit of calcium scoring: among people with a calcium score of zero, 5.5 percent still had plaque on CT angiography, mostly the noncalcified kind.

The dual message defines modern screening. Subclinical disease is extraordinarily common and begins silently; a high calcium score nearly guarantees it; but a zero score does not entirely exclude it, particularly in those with elevated risk factors.

We rate the evidence very strong. A population-based imaging study of this size is exceptional, and it provides some of the clearest data available on how widespread, and how hidden, early coronary disease really is.