Aortic stenosis is a narrowing of the aortic valve, the gateway between the heart’s main pumping chamber and the aorta, the large artery that carries blood to the rest of the body. When this valve stiffens and narrows, the heart has to work much harder to push blood through a smaller opening. It is one of the most common heart valve disorders, and when symptoms appear, it can become life-threatening quickly: average survival is only one to two years without treatment once significant symptoms develop.
What Happens Inside the Heart
Your aortic valve normally has three thin, flexible flaps (called leaflets) that open wide with each heartbeat and snap shut between beats. In aortic stenosis, these leaflets gradually thicken, stiffen, and accumulate calcium deposits. Over time, the edges of the leaflets can fuse together, leaving only a small central opening for blood to squeeze through.
This forces the left ventricle, the heart’s most powerful chamber, to generate much higher pressure to push blood past the obstruction. In response, the heart muscle thickens, the same way a bicep grows when you lift heavy weights repeatedly. For a while, this thickening is a useful adaptation that helps the heart keep up with the extra workload. But the thicker the muscle gets, the more oxygen it needs, and the stiffer the chamber becomes. Eventually the heart can no longer compensate, and it begins to weaken and fail.
Main Causes
The most common cause in older adults is age-related calcium buildup on a normal three-leaflet valve. This process resembles atherosclerosis (the hardening of arteries) and shares many of the same risk factors, including high blood pressure, high cholesterol, smoking, and diabetes. Symptoms from this type of calcification typically appear between ages 70 and 80, and it only affects a subset of people with normal valves.
The second major cause is a bicuspid aortic valve, a congenital variation where the valve has two leaflets instead of three. About 1 to 2 percent of the population is born with this anatomy. Because two leaflets must handle the same workload as three, they experience more mechanical stress with every heartbeat. This accelerated wear means nearly all people with a bicuspid valve will eventually develop significant narrowing, and symptoms tend to show up a decade or two earlier, typically between ages 50 and 60.
Rheumatic heart disease, caused by untreated strep throat, was once a leading cause and remains one in parts of the world with limited access to antibiotics. In these cases, the immune system’s inflammatory response damages the valve leaflets and leads to scarring and fusion.
Risk Factors That Speed Things Up
High blood pressure is independently associated with both aortic valve thickening and progression to stenosis in older adults. This makes sense: when blood pressure is chronically elevated, the valve leaflets endure greater force with every heartbeat, accelerating the damage and calcium buildup. Other conditions that speed the process include chronic kidney disease (which disrupts calcium metabolism), high cholesterol, and smoking. Many of these overlap with risk factors for coronary artery disease, which is why the two conditions often coexist.
Symptoms and Warning Signs
Aortic stenosis is often silent for years or even decades. The heart compensates so effectively that many people have no idea their valve is narrowing. Symptoms tend to appear only once the obstruction becomes severe, and when they do, they follow a recognizable pattern of three hallmark problems.
- Chest pain or tightness with exertion. The thickened heart muscle demands more oxygen, but the narrowed valve limits how much blood (and therefore oxygen) can reach the heart tissue itself. Physical activity widens that gap, producing chest pain similar to what people feel with blocked coronary arteries.
- Fainting or near-fainting, especially during exercise. When you exert yourself, your blood vessels dilate to supply working muscles. A severely narrowed valve can’t increase output to match, so blood pressure drops and the brain briefly loses adequate blood flow.
- Shortness of breath. As the left ventricle stiffens and weakens over time, pressure backs up into the lungs, causing fluid buildup. This starts as breathlessness during activity and can eventually occur at rest or while lying flat. It signals that heart failure is developing.
These three symptoms tend to appear in roughly that order, with chest pain first and heart failure symptoms last. Once any of them appear, the condition’s prognosis worsens dramatically, which is why recognizing them matters.
How It Is Diagnosed
Aortic stenosis is often first suspected when a doctor hears a characteristic heart murmur during a routine exam. The murmur has a distinctive harsh, diamond-shaped sound pattern during each heartbeat. It is loudest over the upper right chest and often radiates up into the neck along the carotid arteries. In older adults, however, the murmur may be quieter and radiate toward the lower left chest instead, which can make it harder to detect.
An echocardiogram (a painless ultrasound of the heart) is the key diagnostic tool. It lets cardiologists see the valve directly, measure how fast blood is moving through it, and calculate the pressure difference across it. Severe aortic stenosis is defined by a peak blood velocity across the valve greater than 4 meters per second and a mean pressure gradient above 40 mmHg. In practical terms, these numbers mean the valve opening has shrunk to roughly a quarter of its normal size, and the heart is generating significantly more pressure than it should need to.
What Happens Without Treatment
Mild and moderate aortic stenosis can remain stable for years, monitored with periodic echocardiograms to track progression. But once the condition becomes severe and symptoms develop, the outlook changes sharply. The average life expectancy after symptom onset is just one to two years without valve replacement, a prognosis that is actually worse than many cancers. This is why cardiologists treat symptomatic severe aortic stenosis as an urgent problem.
Even before symptoms appear, the heart is undergoing changes. The left ventricle is thickening and stiffening, which can lead to abnormal heart rhythms and gradually worsening function. Regular monitoring helps catch the transition from a compensated heart to one that is beginning to struggle, ideally before irreversible damage occurs.
Treatment Options
No medication can reverse or halt valve calcification. Drugs can manage symptoms like fluid retention or high blood pressure, but they do not fix the underlying narrowing. The only definitive treatment is replacing the damaged valve.
There are two main approaches to valve replacement. Surgical aortic valve replacement (SAVR) involves open-heart surgery: the chest is opened, the heart is temporarily stopped, and the diseased valve is cut out and replaced with a new one (either mechanical or made from biological tissue). This has been the standard treatment for decades and remains the preferred option for younger, lower-risk patients. Recovery typically takes several weeks, with a hospital stay of about five to seven days.
Transcatheter aortic valve replacement (TAVR) is a less invasive alternative developed over the past two decades. A replacement valve is compressed onto a catheter, threaded through a large artery (usually in the groin), and expanded into place inside the old valve. There are no large incisions and no need to stop the heart. Hospital stays are often just one to three days, and recovery is significantly faster. TAVR was originally reserved for patients too frail for open-heart surgery, but it has expanded to include moderate- and even some lower-risk patients.
Choosing between the two involves several factors: age, overall health, anatomy, the risk of needing a pacemaker afterward (higher with TAVR), how well the new valve seals (surgical valves tend to have less leakage around the edges), and how long the replacement valve is expected to last. Younger patients may lean toward surgery because surgical valves have a longer track record of durability, while older patients or those with significant health problems often benefit from the quicker recovery of TAVR. These decisions are made by a team of heart specialists who weigh the tradeoffs for each individual.
Living With Aortic Stenosis
If you have been diagnosed with mild or moderate aortic stenosis, you will likely need echocardiograms every one to two years to track the valve’s progression. Managing blood pressure, cholesterol, and other cardiovascular risk factors is important because these conditions can accelerate calcification and also affect overall heart health. Staying physically active is generally encouraged, though your cardiologist may recommend avoiding very intense or competitive exercise once the stenosis reaches a certain severity.
After valve replacement, most people experience a significant improvement in energy, breathing, and overall quality of life. The heart often begins to reverse its thickening within months once the obstruction is removed. Long-term outcomes depend on the type of valve used, with mechanical valves requiring lifelong blood-thinning medication and biological valves eventually wearing out after 10 to 20 years but not requiring blood thinners.