Atherosclerosis is a chronic disease of the arteries in which fatty, cholesterol-rich deposits called plaques build up inside vessel walls, gradually narrowing them and sometimes triggering heart attacks or strokes when a plaque ruptures. It is the underlying cause of most cardiovascular disease worldwide and begins decades before any symptoms appear. What makes atherosclerosis so interesting, and so dangerous, is that it is not simply a plumbing problem of cholesterol clogging a pipe. It is a disease driven by inflammation, immune-cell behavior, and a surprisingly long list of factors that researchers are still cataloguing.
Where Plaques Start and Why Location Matters
If atherosclerosis were just about having too much cholesterol in the blood, plaques would coat arteries evenly. Instead, they cluster at specific spots: branches, curves, and bifurcations where arteries split. The reason is blood flow. In straight segments, blood moves in smooth, parallel layers and exerts a steady force on the vessel lining. At bends and junctions, the flow becomes turbulent and the force irregular. The endothelial cells lining these “disturbed flow” zones respond differently from cells in quieter stretches. They ramp up inflammatory signaling, produce less nitric oxide (a molecule that keeps vessels relaxed and resistant to damage), and become stickier for white blood cells passing by in the bloodstream.1PubMed Central. Shear stress-initiated signaling and its regulation of endothelial function These flow characteristics are so predictive that researchers can map atherosclerosis-prone zones in an artery purely from how blood moves through it.2PubMed Central. Hemodynamic shear stress and the endothelium in cardiovascular pathophysiology
Once the endothelium in these vulnerable zones becomes permeable, low-density lipoprotein (LDL) particles slip beneath the surface into the artery wall. There they get trapped in the extracellular matrix and undergo chemical modification, primarily oxidation. It is the oxidized form of LDL that kicks the disease into motion.3PubMed. Atherosclerosis: basic mechanisms. Oxidation, inflammation, and genetics Oxidized LDL acts as an alarm signal, triggering a cascade of immune responses that, paradoxically, end up making things worse rather than resolving the problem.4PubMed Central. Mechanistic Insights into the Oxidized Low-Density Lipoprotein-Induced Atherosclerosis
How a Fatty Streak Becomes a Dangerous Plaque
The body’s first response to oxidized LDL in the artery wall is to send in cleanup crews. Monocytes, a type of white blood cell, are recruited from the bloodstream and squeeze through the endothelium into the vessel wall. Once inside, they mature into macrophages, immune cells whose job is to engulf and digest debris.5PubMed. Monocyte recruitment and foam cell formation in atherosclerosis In a healthy scenario, macrophages would mop up the oxidized LDL and leave. In atherosclerosis, the lipid load overwhelms them. They gorge on cholesterol until they swell with tiny fat droplets, earning the name “foam cells.” Foam cells are the hallmark of early plaques and the primary immune cells found within them.6PubMed Central. Monocyte Recruitment, Specification, and Function in Atherosclerosis
These foam cells do not sit quietly. They release inflammatory signals that recruit still more monocytes, creating a self-reinforcing loop. Meanwhile, smooth muscle cells from the deeper layers of the artery wall migrate inward and change their behavior. Normally contractile cells that help regulate blood pressure, they start producing collagen and other structural proteins that form a fibrous cap over the growing mass of foam cells and lipid debris.7PubMed Central. Smooth muscle cell phenotypic switching in atherosclerosis This cap is a double-edged feature: it stabilizes the plaque and keeps its contents walled off from the bloodstream, but it also means the plaque is growing.
The Necrotic Core and Why Cleanup Fails
In most tissues, when cells die by programmed cell death, neighboring cells promptly clear the debris through a process called efferocytosis. Inside an atherosclerotic plaque, this cleanup mechanism breaks down. Foam cells and macrophages die in large numbers, but instead of being efficiently removed, their remains accumulate. The result is a growing necrotic core of dead cells, cholesterol crystals, and cellular debris at the center of the plaque.8PubMed Central. The Role of Efferocytosis in Atherosclerosis
Research suggests this happens because the molecular signals that flag dying cells for removal become dysregulated within the plaque environment. In mouse models, knocking out a key receptor involved in efferocytosis led to a significant increase in dead cells that were not associated with macrophages, meaning nobody was picking them up. Over time, these plaques became more necrotic.9PubMed Central. Mertk receptor mutation reduces efferocytosis efficiency and promotes apoptotic cell accumulation and plaque necrosis in atherosclerotic lesions of apoe-/- mice The necrotic core matters clinically because its size is one of the strongest predictors of whether a plaque will remain stable or suddenly rupture.
Two Ways a Plaque Can Cause a Heart Attack
Not all dangerous plaques fail the same way. The classic scenario is plaque rupture. A thin fibrous cap, weakened by ongoing inflammation and enzymatic digestion, tears open. The necrotic core underneath is intensely thrombogenic, meaning it triggers rapid blood clot formation on contact with circulating blood. A clot forming at the rupture site can partially or completely block the artery, and if it happens in a coronary artery, the result is a heart attack. Ruptured plaques tend to be rich in macrophages and foam cells at their edges and have a large lipid core, sometimes with signs of bleeding inside the plaque itself.10European Heart Journal. Platelet biology and function: plaque erosion vs. rupture
The second, increasingly recognized scenario is plaque erosion. Here the fibrous cap stays intact, but the endothelial layer on the plaque’s surface is lost, exposing the underlying smooth muscle cells and connective-tissue matrix to the bloodstream. Erosion-prone plaques look quite different under a microscope: they are dominated by smooth muscle cells rather than macrophages, and inflammation is comparatively mild. Neutrophil extracellular traps, web-like structures released by a different type of white blood cell, appear to play a role in triggering clot formation on eroded plaques.11European Heart Journal. Platelet biology and function: plaque erosion vs. rupture Some estimates suggest that erosion accounts for roughly a quarter to a third of acute coronary events, and this proportion may be growing as statin therapy shifts the balance of plaque types.
The Inflammation Engine Inside the Plaque
A key molecular player driving inflammation within plaques is the NLRP3 inflammasome, an immune-signaling complex that acts as an intracellular alarm system. Danger signals abundantly present in plaques, including oxidized LDL and cholesterol crystals, activate NLRP3. Once triggered, it sets off production of potent inflammatory messengers, particularly IL-1β and IL-18, through an enzyme cascade.12PubMed. NLRP3 Inflammasome and the IL-1 Pathway in Atherosclerosis These molecules promote further endothelial dysfunction, oxidative stress, and recruitment of immune cells, amplifying the inflammatory cycle that makes plaques grow and destabilize.13PubMed Central. Portrayal of NLRP3 Inflammasome in Atherosclerosis: Current Knowledge and Therapeutic Targets
Understanding this pathway transformed how cardiologists think about treatment. For decades, the field focused almost exclusively on lowering cholesterol. The NLRP3-IL-1β axis provided a clear molecular target for anti-inflammatory therapy, and the clinical trials that followed have started to reshape prevention strategies.
Risk Factors You Might Not Have Heard Of
High LDL cholesterol, smoking, high blood pressure, and diabetes are the well-known drivers. But several less familiar risk factors deserve attention.
Lipoprotein(a)
Lipoprotein(a), often written as Lp(a), is a particle similar to LDL but with an extra protein attached. Your Lp(a) level is largely determined by genetics and does not respond much to diet or standard cholesterol drugs. Elevated Lp(a) raises cardiovascular risk independently of LDL cholesterol, meaning you can have a “normal” LDL level and still face increased danger from atherosclerosis if your Lp(a) runs high.14PubMed Central. Lipoprotein(a) as a Risk Factor for Cardiovascular Diseases: Pathophysiology and Treatment Perspectives High Lp(a) has also been linked to aortic valve stenosis and heart failure. Despite being identified as a risk factor decades ago, Lp(a) is still not routinely tested in many countries, and specific therapies targeting it are only now reaching late-stage clinical trials.15Journal of Atherosclerosis and Thrombosis. Lipoprotein(a) as an Old and New Causal Risk Factor of Atherosclerotic Cardiovascular Disease
Clonal Hematopoiesis
As people age, some of their blood-forming stem cells acquire DNA mutations that give those cells a growth advantage. The mutant stem cells expand into a larger clone, producing immune cells that carry the mutation. This condition, called clonal hematopoiesis of indeterminate potential (CHIP), becomes common with age and is associated with roughly a doubling of atherosclerotic cardiovascular risk.16Nature Reviews Cardiology. Clonal haematopoiesis: connecting ageing and inflammation in cardiovascular disease The leading theory is that the mutant immune cells, especially macrophages, are more inflammatory. Mouse studies have shown that transplanting bone marrow with mutations in the TET2 gene, one of the most commonly affected genes in CHIP, produces larger atherosclerotic lesions and elevated expression of inflammatory genes in macrophages.17PubMed Central. Clonal Hematopoiesis and Risk of Atherosclerotic Cardiovascular Disease The inflammatory mechanism appears to run through the same IL-1 and IL-6 pathways already implicated in plaque growth.18PubMed Central. Clonal Hematopoiesis of Indeterminate Potential From a Heart Failure Specialist’s Point of View
The Gut Microbiome and TMAO
When you eat foods rich in certain nutrients, such as phosphatidylcholine (found in eggs, red meat, and other animal products), gut bacteria metabolize them into a compound that the liver converts to trimethylamine N-oxide, or TMAO. Higher blood levels of TMAO have been associated with a greater risk of major cardiovascular events. In one large study, people in the highest quarter of TMAO levels had about two and a half times the risk of a major adverse cardiovascular event compared with those in the lowest quarter, even after adjusting for traditional risk factors.19PubMed Central. Intestinal microbial metabolism of phosphatidylcholine and cardiovascular risk This finding opened an entire research field connecting the composition of gut bacteria to heart disease, though exactly how TMAO promotes atherosclerosis at the molecular level is still being worked out.
How Diabetes Accelerates the Process
People with diabetes develop atherosclerosis earlier, more diffusely, and more aggressively than the general population. A major reason is a class of molecules called advanced glycation end products, or AGEs. In the setting of high blood sugar and oxidative stress, AGEs form at a greatly accelerated rate. Within the artery wall, they do several damaging things at once: they trap proteins onto collagen, quench nitric oxide, promote the oxidation of LDL particles, and activate inflammatory signaling in endothelial cells, macrophages, and smooth muscle cells. The net effect is increased vascular permeability, greater immune-cell adhesion, enhanced clotting activity, and more reactive oxygen species, all of which pour fuel on the atherosclerotic fire.20Cardiovascular Research. Advanced glycation end products and vascular inflammation: implications for accelerated atherosclerosis in diabetes This is why tight blood-sugar control matters not just for preventing nerve or kidney damage but for protecting arteries.
Detecting Atherosclerosis Before It Causes Symptoms
Because plaques grow silently for decades, a major clinical challenge is identifying people at risk before their first heart attack. One of the most practical tools is the coronary artery calcium (CAC) score, measured with a fast, low-dose CT scan. Calcium deposits in the coronary arteries are a marker of atherosclerotic plaque burden. A score of zero means no detectable calcification and a very low near-term risk. Scores above 300 carry substantially elevated risk: one study found that people with a score over 300 had about four times the risk of a fatal or non-fatal heart attack compared with those who scored zero.21JAMA. Coronary Artery Calcium Score Combined With Framingham Score for Risk Prediction in Asymptomatic Individuals The CAC score adds useful information even on top of traditional risk calculators that rely on blood pressure, cholesterol, and smoking status. It has also been shown to independently predict all-cause mortality when performed during routine lung-cancer screening CT scans.22PubMed. Coronary artery calcium can predict all-cause mortality and cardiovascular events on low-dose CT screening for lung cancer
A CAC score is most useful for people whose risk is genuinely uncertain from standard blood work alone, particularly those in the “borderline” risk category where a doctor might be on the fence about whether to start a statin. A zero score can provide reassurance and sometimes allow deferral of medication, while a high score often tips the decision toward treatment.
Treating the Inflammation, Not Just the Cholesterol
Statins remain the backbone of atherosclerosis treatment. They lower LDL cholesterol and also appear to have modest anti-inflammatory effects. But for many patients, “residual risk” persists even with well-controlled cholesterol levels, suggesting that inflammation is doing damage independent of lipid levels.
Enter colchicine, a centuries-old anti-inflammatory drug traditionally used for gout. Low-dose colchicine, just half a milligram daily, has shown striking results when added on top of standard preventive therapy. In a large randomized trial of patients with chronic coronary disease already taking statins, colchicine reduced the primary composite of cardiovascular death, heart attack, stroke, or urgent need for coronary intervention by about 31% compared with placebo.23PubMed. Colchicine in Patients with Chronic Coronary Disease An earlier, smaller trial found an even larger reduction, with cardiovascular events dropping from 16% in the control group to about 5% in those taking colchicine.24PubMed. Low-dose colchicine for secondary prevention of cardiovascular disease A review of the colchicine trials noted that these benefits were larger than those seen in recent secondary-prevention trials of additional lipid-lowering drugs, underscoring just how much of atherosclerotic risk is inflammatory rather than purely cholesterol-driven.25PubMed. Low-Dose Colchicine for Secondary Prevention of Coronary Artery Disease: JACC Review Topic of the Week
Can Atherosclerosis Actually Be Reversed?
For years the assumption was that plaque buildup was a one-way street. That has changed. Studies using intravascular ultrasound, which can measure plaque volume directly inside a coronary artery, have shown that aggressive lipid lowering can shrink plaques. Intensive statin therapy has been shown to regress plaque volume by roughly 7 to 9% across various measures of disease burden. Adding a PCSK9 inhibitor on top of statins pushes things further. PCSK9 is a protein that tags LDL receptors on liver cells for destruction; when it is blocked, more receptors survive and pull more LDL out of the bloodstream.26PubMed Central. PCSK9 and LDLR degradation: regulatory mechanisms in circulation and in cells In one trial, patients receiving the PCSK9 inhibitor evolocumab alongside a statin showed a nearly 1% absolute decrease in the percentage of artery volume occupied by plaque over about 18 months, while the placebo group showed essentially no change.27American College of Cardiology. Global Assessment of Plaque Regression With a PCSK9 Antibody as Measured by Intravascular Ultrasound – GLAGOV
Regression does not mean the artery returns to a pristine state. Calcium and scar tissue within old plaques persist even as lipid content shrinks. What appears to happen is that the plaque stabilizes and becomes less likely to rupture, which is what matters clinically. The calcification left behind may even be protective in a sense, hardening the cap and making it less prone to tearing. This is also why a rising CAC score after starting treatment does not necessarily mean things are getting worse: dense calcification in a shrunken, stable plaque is not the same threat as soft, lipid-rich plaque in a thinly capped lesion.
A Newer Piece of the Puzzle: Lymphatic Drainage
An emerging line of research concerns the lymphatic vessels that run alongside arteries. These tiny vessels are responsible for draining fluid, immune cells, and large molecules away from tissues. In mouse models, lymphatic drainage from the aorta becomes impaired as atherosclerosis progresses. When researchers physically blocked lymphatic flow from the aorta, inflammation in the vessel wall increased and plaques grew. Conversely, when they induced plaque regression using the cholesterol-absorption blocker ezetimibe, lymphatic transport improved along with it. Deliberately disrupting the lymphatic outflow prevented the drug from shrinking plaques.28PubMed Central. Efficient aortic lymphatic drainage is necessary for atherosclerosis regression induced by ezetimibe The implication is that plaque growth is partly a drainage problem: atherogenic material accumulates not just because too much enters the artery wall, but because too little is being carried away. Whether this can be targeted therapeutically in humans is still speculative, but it reframes the disease in a way that could eventually open new treatment approaches.
Atherosclerosis Is Not a Modern Disease
One of the most persistent misconceptions about atherosclerosis is that it is a product of modern diets and sedentary living. CT scans of mummies from ancient Egypt tell a different story. In the original Horus study, about 45% of mummies with identifiable vascular structures had definite or probable calcified atherosclerosis, with deposits found in the aorta, coronary arteries, carotid arteries, and leg arteries spanning over 2,000 years of Egyptian history.29PubMed. Atherosclerosis in ancient Egyptian mummies: the Horus study
Expanded studies have only strengthened the point. When researchers scanned mummies from four different ancient populations, including ancient Egyptians, Peruvians, Ancestral Puebloans, and Unangan hunter-gatherers from the Aleutian Islands, about a third across all groups had evidence of atherosclerosis.30The Lancet. Atherosclerosis across 4000 years of human history: the Horus study of four ancient populations The global Horus study, which eventually analyzed 237 mummies from diverse cultures and time periods, found definite or probable atherosclerosis in about 38% of them. The aorta was the most commonly affected vessel.31European Heart Journal. Atherosclerosis in ancient mummified humans: the global HORUS study
The presence of atherosclerosis in pre-agricultural hunter-gatherers, who presumably ate no processed food and were physically active, suggests that the disease has a basic predisposition in humans that goes beyond lifestyle. Aging itself, chronic infections, smoke exposure from cooking fires, and genetic susceptibility likely contributed. Modern risk factors clearly amplify the disease, but they did not invent it. The evidence from mummies aligns with newer findings about clonal hematopoiesis and other age-linked processes: some degree of arterial inflammation and plaque formation may simply be part of the human condition once we live long enough.
Chronic Stress and the Vessel Wall
Psychological and physiological stress have long been suspected of worsening cardiovascular disease, and emerging research is starting to clarify how. Chronic stress activates the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis, leading to sustained elevations in cortisol, catecholamines, and inflammatory markers. In people with genetic susceptibility, the combination of prolonged stress and environmental risk factors can accelerate plaque instability, potentially contributing to vessel blockage and plaque rupture.32PubMed Central. Recent Progress of Chronic Stress in the Development of Atherosclerosis Imaging studies in recent years have connected activity in the amygdala, a brain region involved in processing fear and stress, with subsequent arterial inflammation and cardiovascular events, suggesting a direct brain-to-artery signaling pathway. The clinical takeaway is that stress management is not just about feeling better. It has a plausible biological connection to what is happening inside your arteries.