Coronary artery disease is caused by the gradual build-up of fatty deposits, called plaque, in the walls of the arteries that supply blood to the heart muscle. This process is known as atherosclerosis, and it develops over decades. The main factors that drive it are high cholesterol, high blood pressure, smoking, diabetes and a family history of early heart disease, alongside contributors such as obesity, physical inactivity, poor diet and excess alcohol. Most of these are things you can influence, which is why coronary artery disease is so often preventable.
Understanding the cause matters because it reshapes how you think about the condition. Coronary artery disease is not something that arrives suddenly. It is the slow result of the artery lining being damaged, repaired, and damaged again, year after year, until the deposits that form begin to narrow the vessel or become unstable. Over more than 20 years as a Consultant Cardiologist at Kingston Hospital, much of that as Clinical Lead of the department, and across my private clinics at Parkside, The New Victoria, Cleveland Clinic London and Heartsure, the point I return to most often with patients is that the disease is usually decades in the making, which means there is usually a long window in which its course can be changed. What causes coronary artery disease is, for the most part, a set of factors that can be identified and addressed long before symptoms appear.
How the disease actually develops
To understand the causes, it helps to understand the process they set in motion. The inner lining of a healthy artery, called the endothelium, is smooth and allows blood to flow freely. The trouble begins when this lining is damaged, and the main things that damage it are the classic risk factors. High blood pressure batters it mechanically. High LDL cholesterol allows fatty particles to penetrate it. The chemicals in tobacco smoke injure it directly. High blood glucose in diabetes makes it stiff and inflamed.
Once the lining is damaged, LDL cholesterol particles work their way into the artery wall, where they trigger an inflammatory response. The body sends immune cells to deal with them, and over time this mixture of fat, inflammatory cells and debris forms a plaque. The plaque grows slowly, narrowing the channel through which blood flows. When the narrowing becomes significant enough to limit blood supply during exertion, it produces the chest discomfort of angina. If a plaque ruptures and a clot forms on top of it, the result is a heart attack.
This is the crucial insight that shapes everything about prevention. The disease is driven by inflammation and cholesterol infiltration, not simply by fatty food clogging a pipe, and it is why treatments that stabilise plaque and lower cholesterol matter as much as anything that physically widens the artery. The BHF explanation of coronary heart disease sets out this process in accessible detail.
Cholesterol, the central driver
Of all the causes, cholesterol sits closest to the heart of the disease, because without LDL cholesterol infiltrating the artery wall, plaque does not form in the way it does. This is why LDL, often called the harmful cholesterol, is such a strong predictor of coronary artery disease, and why lowering it reduces risk so reliably.
The relationship is consistent across the evidence. The higher the LDL and the longer it stays high, the greater the accumulation of plaque over a lifetime. This is also why familial hypercholesterolaemia, an inherited condition causing very high cholesterol from birth, leads to coronary disease at a strikingly young age. What I have seen across many years of practice is that lifetime exposure to cholesterol matters more than a single reading in middle age, because the plaque reflects decades of accumulation rather than the number on one particular day. This is the argument for identifying and treating high cholesterol early rather than waiting.
High blood pressure
High blood pressure causes coronary artery disease through the sustained mechanical stress it places on the artery lining. Every heartbeat drives blood against the vessel wall at higher pressure than it should, and over years this damages the endothelium and accelerates the formation of plaque. It also thickens and stiffens the arteries, making them less able to respond to the heart’s changing demands.
The insidious feature of high blood pressure is that it produces no symptoms while it is doing this damage. Many of the patients I see with established coronary disease had raised blood pressure for years without knowing, which is why measuring it matters so much. The good news, covered in more depth in the guidance on managing blood pressure naturally, is that controlling it substantially slows the process, whether through lifestyle change, medication, or both.
Smoking
Smoking is one of the most powerful causes of coronary artery disease, and it acts through several mechanisms at once. The chemicals in tobacco smoke injure the artery lining directly, make the blood more likely to clot, reduce the oxygen the blood can carry, and lower the level of protective HDL cholesterol. The effect is to accelerate every stage of the disease.
The encouraging side is how quickly the picture begins to improve on stopping. The risk of a heart attack falls steadily after quitting, and over a decade or more approaches that of someone who never smoked. Drawing on the smokers I have supported over the years, structured support through the NHS Stop Smoking Service works better than willpower alone, because the combination of behavioural support and nicotine replacement produces far lower relapse rates than trying to stop unaided.
Diabetes and blood glucose
Type 2 diabetes is a major cause of coronary artery disease, and it is a particularly dangerous one because it damages arteries throughout the body while frequently causing few symptoms. High blood glucose makes the artery lining inflamed and stiff, accelerates plaque formation, and interacts with other risk factors to multiply the overall danger.
People with diabetes can develop advanced coronary disease with little of the usual warning discomfort, which is one reason silent heart attacks occur more often in this group. This is why I treat diabetes, and even pre-diabetes, as a strong reason for careful cardiovascular assessment. The BHF material on diabetes and the heart explains the connection well.
Family history and genetics
You cannot change your genes, but they clearly influence your risk. A family history of coronary artery disease, particularly a parent or sibling affected before the age of 60, raises your own risk meaningfully. This reflects both inherited tendencies towards high cholesterol, high blood pressure or diabetes, and genetic factors that act more directly on the arteries.
One genetic factor worth highlighting is lipoprotein(a), an inherited particle that raises cardiovascular risk independently of ordinary cholesterol and is not routinely measured. Looking back at the younger patients I have seen with coronary disease and no obvious risk factors, checking lipoprotein(a) works better than relying on a standard cholesterol panel alone in this group, because it frequently reveals an inherited driver that the usual tests miss entirely. A strong family history should never be met with fatalism, though. It is a reason for earlier and more thorough assessment, because the inherited risk can very often be offset by managing everything else well.
The contributing lifestyle factors
Beyond the major causes sit several contributors that add to the overall picture. Obesity, particularly fat carried around the abdomen, drives up blood pressure, worsens cholesterol and raises the risk of diabetes. Physical inactivity harms the artery lining and worsens nearly every other risk factor. A diet high in saturated fat, salt and ultra-processed food pushes cholesterol and blood pressure in the wrong direction, while excess alcohol raises blood pressure and adds empty calories, as covered in the discussion of alcohol and heart health.
Poor sleep and untreated sleep apnoea are increasingly recognised as contributors, raising blood pressure and promoting inflammation. Chronic stress plays a part too, both directly and through the behaviours it encourages. None of these acts as powerfully alone as cholesterol or smoking, but together they shape the environment in which the disease either progresses or is held back.
Why the causes matter more than the symptoms
The reason I spend so much time on causes with patients is that coronary artery disease is largely silent until it is advanced. By the time symptoms such as angina appear, the disease has usually been developing for many years. Waiting for symptoms is therefore a poor strategy, because it means acting late in a process that was modifiable for a long time beforehand.
This is the thinking behind reducing risk before anything happens, which is explored in the guidance on how to reduce your risk of a heart attack. The causes are, in the main, measurable and treatable, which means the disease can be slowed or even partially stabilised when they are addressed early enough.
How I assess coronary artery disease in clinic
When a patient comes to me with risk factors or symptoms, the assessment is built around understanding both their overall risk and what is actually happening in their arteries. It usually begins with a detailed history and examination, an ECG, and blood tests covering cholesterol, glucose and kidney function. An echocardiogram assesses the heart muscle and looks for evidence of previous damage.
The test that has changed this area most is the CT coronary angiogram, which produces a detailed image of the arteries themselves and can detect disease at an early stage, often before it causes any symptoms. Drawing on the patients I have investigated in recent years, a CT coronary angiogram works better than a risk score alone for many patients, because it shows the actual state of the arteries rather than estimating risk from population averages, and it frequently changes how intensively I treat someone in either direction. Where significant narrowing is found, an invasive coronary angiogram allows the disease to be mapped precisely and treatment planned, whether through medication, stenting with Professor Simon Redwood, or bypass surgery with Mr Chandrasekaran.
When to seek a cardiology opinion
A specialist assessment is worth arranging if you have a family history of heart disease before the age of 60, if you have high cholesterol, high blood pressure or diabetes, or if you have symptoms such as chest discomfort on exertion, breathlessness or reduced exercise tolerance. It is also worth arranging if you simply want a clear understanding of the state of your arteries and your personal risk, particularly if you have several risk factors together.
You can read verified feedback from patients I’ve seen if it helps you decide whether a private cardiology opinion is the right step for you.
Conclusion
Coronary artery disease is caused by the slow build-up of plaque in the heart’s arteries, driven above all by cholesterol, high blood pressure, smoking, diabetes and inherited risk, with lifestyle factors such as weight, inactivity, diet, alcohol and sleep adding to the picture. What unites almost all of these causes is that they are identifiable and, in most cases, treatable. The disease develops over decades, which is precisely what gives it such a long window for prevention. The patients who do best are the ones who understand what is driving the process and act on it early, rather than waiting for the symptoms that mark its later stages.
If you would like to understand your own risk of coronary artery disease, or you have symptoms that concern you, you can contact me, Dr Arvind Vasudeva, on 020 8977 4826 to arrange an assessment. I consult at Parkside Hospital in Wimbledon, The New Victoria Hospital in Kingston, Cleveland Clinic London and the Heartsure Clinic, and you can book a convenient appointment here through my secretary Hannah.