Angina Pectoris

How angina happens

The heart muscle receives blood through the coronary arteries. When fatty plaque narrows an artery by roughly 70% or more, blood flow is adequate at rest but cannot increase enough during exertion. The heart muscle becomes short of oxygen (ischemic), and nerve signals produce the discomfort of angina. Once demand falls with rest, flow catches up and the pain fades, usually without lasting damage.

Angina can also happen when:

• an artery goes into spasm
• the tiny vessels inside the heart muscle do not dilate normally
• the heart's demand is very high, as with a thickened heart muscle, a very fast heart rate or severe anemia
• the aortic valve is narrowed (aortic stenosis)

Symptoms

Angina usually feels like pressure, tightness or heaviness behind the breastbone that may spread to the arms, neck, jaw or back, with breathlessness. Women, older adults and people with diabetes more often have breathlessness, fatigue or nausea instead of classic chest pain. See angina symptoms for how to recognize it and what to do.

Types of angina

Stable angina

The most common type. Attacks follow a predictable pattern: the same level of activity triggers them, they last less than 5 minutes, and rest or nitroglycerin relieves them. It reflects a fixed narrowing of a coronary artery.

Unstable angina

Angina that is new, increasing in frequency or severity, or happening at rest. A plaque has cracked and a clot is partly blocking the artery. It is part of acute coronary syndrome and needs emergency treatment, because it can progress to a heart attack within hours or days.

Variant (vasospastic or Prinzmetal) angina

Caused by coronary artery spasm. Attacks occur at rest, often between midnight and early morning, and may be triggered by cold, smoking, cocaine or stress. It responds well to calcium channel blockers and nitrates.

Microvascular angina

Caused by dysfunction of the small blood vessels of the heart. Episodes may last longer and occur with stress. Standard angiograms often look normal. It is more common in women. Doctors sometimes call it ischemia with no obstructive coronary arteries (INOCA).

Causes and risk factors

The underlying cause is usually coronary atherosclerosis. Risk factors include:

• smoking
• high blood pressure
• high LDL cholesterol (hyperlipidemia)
• diabetes
• obesity and physical inactivity
• older age (men over 45, women over 55)
• family history of early heart disease
• chronic kidney disease
• sleep apnea and chronic stress

Less common causes include hypertrophic cardiomyopathy, aortic stenosis, severe anemia, an overactive thyroid and fast heart rhythms.

Diagnosis

1. History: what triggers the pain, how long it lasts, what relieves it, and your risk factors.
2. Examination: blood pressure, heart murmurs, signs of heart failure.
3. ECG: often normal between attacks; may show old damage or strain.
4. Blood tests: troponin to rule out a heart attack if symptoms are recent; cholesterol, blood sugar, kidney function and blood count.
5. Non-invasive testing: - CT coronary angiography: shows narrowing and calcium in the arteries; often the first test for suspected stable angina. - Stress testing: exercise ECG, stress echocardiogram, nuclear perfusion scan or stress MRI to show areas of the heart short of blood.
6. Invasive coronary angiography: dye injected through a catheter shows the arteries in detail and allows stenting in the same procedure.

Treatment

Relieving attacks

Nitroglycerin spray or tablets under the tongue widen blood vessels and relieve angina within 1 to 5 minutes. It can also be used just before activities known to trigger angina. Common side effects are headache and flushing. Never combine it with erectile dysfunction medicines such as sildenafil or tadalafil.

Preventing attacks

• Beta-blockers: slow the heart and reduce its oxygen demand. Often first choice.
• Calcium channel blockers: relax arteries; first choice for variant angina.
• Long-acting nitrates, ranolazine and ivabradine: added when needed.

Reducing heart attack risk

• Antiplatelet therapy such as low-dose aspirin, as prescribed
• Statins to lower LDL cholesterol, often with a target below about 70 mg/dL (1.8 mmol/L) or lower
• Blood pressure control, often including ACE inhibitors
• Diabetes management, including newer medicines with heart benefits

Procedures

• Percutaneous coronary intervention (PCI): a balloon and stent open a narrowed artery through a catheter. It relieves symptoms well. For stable angina it does not, on average, prevent heart attacks better than optimal medicines.
• Coronary artery bypass grafting (CABG): surgery that reroutes blood around blockages. It is preferred for disease of the left main artery or multiple arteries, especially with diabetes or a weak heart.

Lifestyle

• stop smoking completely
• cardiac rehabilitation and regular exercise within your angina threshold
• a Mediterranean-style diet low in saturated fat and salt
• weight loss if overweight
• limit alcohol
• manage stress and treat sleep apnea

Complications

The main complications are heart attack, heart failure, dangerous heart rhythms and sudden cardiac death. These risks fall substantially with medicines and lifestyle change.

Outlook

Many people with stable angina live for decades with good quality of life. The outlook is best for people who stop smoking, take statins and antiplatelet medicine, control blood pressure and blood sugar, and stay active. Any change in the pattern of angina should be reported promptly.

Frequently asked questions

What is the main cause of angina?

The main cause is coronary artery disease, where fatty plaques narrow the arteries supplying the heart. Less common causes include coronary artery spasm, small vessel disease, aortic valve narrowing, a thickened heart muscle and severe anemia.

What is the difference between stable and unstable angina?

Stable angina is predictable: it comes on with a familiar level of exertion and eases within minutes of rest. Unstable angina is new, worsening or occurs at rest, because a plaque has ruptured. Unstable angina is an emergency that can lead to a heart attack.

Can angina be cured?

The underlying artery disease cannot be cured, but angina can often be controlled completely. Medicines, stents or bypass surgery relieve symptoms, and stopping smoking, statins, exercise and blood pressure control slow the disease and lower the risk of heart attack.

Can you live a long life with angina?

Yes. With treatment, many people live for many years with stable angina. Taking prescribed medicines, attending cardiac rehabilitation, staying active and controlling risk factors improve both symptoms and life expectancy.

Can you exercise with angina?

Yes, and it is encouraged. Regular, moderate exercise improves how much you can do before angina starts. A cardiac rehabilitation program helps you exercise safely. Stop and rest if chest discomfort begins, and use nitroglycerin as prescribed.