CT angiography & Cleerly

Coronary CT angiography (with contrast) images both the channel and the artery wall: total plaque burden, degree of narrowing (graded CAD-RADS), and composition — calcified vs. non-calcified vs. dangerous low-attenuation plaque. In SCOT-HEART, CTA-guided care cut heart attacks by ~41% at 5 years versus standard care. The cost is more radiation and an iodine contrast injection — but it's the definitive non-invasive look at what's in the wall. Evidence ●●●●○

Cleerly (FDA-cleared) runs AI over a CT angiogram to measure every plaque, quantify total and low-attenuation (vulnerable) plaque, and track change over time. The advantage over a calcium score is direct: it detects and quantifies the soft plaque a CAC scores as zero, flags the most rupture-prone type, and gives a per-vessel number you can re-measure to see if treatment is working — turning '0 calcium, all clear' into 'here's your actual soft-plaque burden.'

It's newer and adds cost, and the trials proving that acting on an AI plaque readout changes hard outcomes (rather than simply informing and motivating) are still maturing. It's outstanding for staging disease and for the 'zero calcium but worried' younger patient, and it's a powerful motivator — but it hasn't yet displaced the humble, cheap CAC on proven cost-effectiveness. Evidence ●●●○○ for changing outcomes

Ultrasound of the neck arteries is cheap and radiation-free, and can find plaque a calcium score misses in younger people — a reasonable screen when a CT isn't warranted. The limits: it's operator-dependent, and it looks at the carotids as a proxy, not the coronary arteries themselves.