Executive Summary
Coronary arteries can enlarge outward as plaque accumulates, a process called positive remodeling. The lumen may therefore look only mildly narrowed even when the arterial wall contains substantial plaque.
Plaque rupture exposes thrombogenic material to blood. Platelets and coagulation can then create an occlusive thrombus quickly. The severity of stenosis before the event is therefore an imperfect predictor of which plaque will cause the next MI.
In SCOT-HEART, roughly half of subsequent myocardial infarctions in the CCTA arm occurred in patients whose baseline disease was non-obstructive. Plaque burden and adverse plaque characteristics predicted risk beyond a simple obstructive/non-obstructive label.
PROMISE similarly showed that non-obstructive CAD is common and accounts for a substantial share of events. CCTA-defined high-risk features include low attenuation, positive remodeling and the napkin-ring sign.
MINOCA is related but different: it describes a myocardial infarction in which invasive angiography shows no obstructive stenosis at the time of the event. Causes include plaque disruption, coronary spasm, microvascular dysfunction, embolism and spontaneous coronary dissection.
The 2024 PREVENT trial was the first large randomized trial to show fewer lesion-related adverse events when selected non-flow-limiting vulnerable plaques were treated with preventive PCI in addition to optimal medical therapy. It does not mean every 20-40% plaque should be stented.
Figure 1. A plaque can be non-flow-limiting before rupture and then become abruptly occlusive after thrombosis.
1. The Mistake: Equating Stenosis With Risk
Angiography historically focused attention on the lumen. A 70% stenosis looks dangerous because it can limit flow, but plaque biology occurs in the vessel wall. Outward remodeling can preserve the lumen during years of plaque accumulation.
2. What Actually Causes the Acute Event
Plaque rupture is the classic mechanism: a thin fibrous cap tears, blood contacts thrombogenic necrotic-core material, and platelet-rich thrombus forms. Plaque erosion is another important mechanism in which the endothelial surface is lost without classic rupture.
The key point is temporal. The plaque may be stable and non-obstructive on Tuesday and become a thrombotic occlusion on Wednesday. The pre-event stenosis percentage cannot fully predict that transition.
3. SCOT-HEART and PROMISE
SCOT-HEART showed that CCTA changes prevention because it detects disease that functional testing or symptoms alone can miss. At five years, CT-guided care reduced fatal or nonfatal MI. Approximately half of subsequent MIs in the CCTA arm occurred in patients with non-obstructive disease at baseline.
In a SCOT-HEART plaque analysis, adverse plaque features were associated with about a three-fold higher risk of coronary death or nonfatal MI, although total plaque burden reflected by CAC was a powerful independent driver.
PROMISE analyses likewise showed that patients with non-obstructive CAD account for many events because they are far more numerous than patients with severe obstruction.
4. High-Risk Plaque Features
| Feature | Why it matters |
|---|---|
| Low attenuation | CT correlate of lipid-rich/necrotic-core plaque. |
| Positive remodeling | Artery expands outward, allowing large plaque with modest stenosis. |
| Napkin-ring sign | High-risk morphology associated with future events. |
| Spotty calcification | Marker of active/mixed plaque biology. |
| High total plaque burden | Often more prognostically important than any single lesion feature. |
5. MINOCA Is Not the Same Thing
MINOCA is a clinical syndrome after an MI has occurred. OCT studies show that plaque disruption and thrombus are present in a meaningful subset, but vasospasm, microvascular dysfunction, embolism, myocarditis and other mechanisms must also be considered.
6. PREVENT: Does This Mean We Should Stent Vulnerable Plaques?
PREVENT randomized 1,606 patients with selected non-flow-limiting vulnerable coronary plaques to preventive PCI plus optimal medical therapy or optimal medical therapy alone. At two years, the primary lesion-related composite occurred in 0.4% versus 3.4%, respectively.
This was a landmark proof-of-concept result, but it was the first large trial of its kind, used invasive imaging/physiology to select lesions, and does not justify prophylactically stenting every non-obstructive plaque seen on CCTA.
Most plaque risk remains systemic and diffuse. Even if one lesion is treated, untreated plaques remain throughout the coronary tree. That is why LDL-C/ApoB lowering, smoking cessation, blood-pressure control, diabetes management and exercise remain the foundation.
The lesson of vulnerable-plaque imaging is not “stent every plaque.” It is “do not mistake a wide lumen for absence of disease.”
7. FAQ
Can a 30% plaque cause a heart attack?
Yes. If it ruptures or erodes and triggers thrombosis, a previously non-flow-limiting plaque can become acutely occlusive.
Does that mean stenosis does not matter?
No. Obstructive disease matters for ischemia, symptoms and prognosis. It is simply not the only determinant of acute MI risk.
Should high-risk plaque on CCTA be stented?
Not routinely. PREVENT is important but applied to highly selected lesions evaluated invasively. Medical prevention remains standard for most non-obstructive plaque.
Can CCTA predict exactly which plaque will rupture?
No. It can identify higher-risk phenotypes and total burden, but positive predictive value for a single future culprit lesion remains limited.
References
1. Newby DE, Adamson PD, Berry C, et al. Coronary CT Angiography and 5-Year Risk of Myocardial Infarction: SCOT-HEART. N Engl J Med. 2018.
2. Williams MC, Moss AJ, Dweck M, et al. Coronary artery plaque characteristics associated with adverse outcomes in SCOT-HEART. J Am Coll Cardiol. 2019.
3. Ferencik M, et al. Risk stratification with CCTA in patients with nonobstructive coronary artery disease: PROMISE. JACC Cardiovasc Imaging. 2021.
4. Park SJ, Ahn JM, Kang DY, et al. Preventive PCI versus optimal medical therapy for vulnerable non-flow-limiting plaques (PREVENT). Lancet. 2024;403:1753-1765.
5. Opolski MP, et al. Mechanisms of myocardial infarction in patients with nonobstructive coronary artery disease: OCT study. JACC Cardiovasc Imaging. 2019.
6. 2023 AHA/ACC Guideline for the Management of Patients With Chronic Coronary Disease.