The connection and difference between atrial fibrillation and coronary artery disease can be confusing. Atrial fibrillation (AFib) is a form of arrhythmia, or abnormal heart rhythm. Coronary artery disease (CAD) is a condition where blockages in major blood vessels reduce the flow of blood, oxygen, and nutrients to the heart.
The two conditions have many similarities. Both AFib and CAD are common, and both are forms of heart disease. Older people have a higher risk of developing AFib and CAD. Many of the symptoms and risk factors are the same. There’s a strong correlation between the two. If you happen to develop both of them, AFib and CAD can aggravate each other in a vicious cycle that can limit your lifespan.
Between 18% and 47% of people with AFib also have CAD, partly due to common risk factors such as older age, hypertension, and diabetes, but only 0.2% to 5% of people with CAD also have AFib. The number of people who have both is rising rapidly.
With AFib, often there are no symptoms. You may notice a fast, pounding heartbeat (called palpitations), shortness of breath, or weakness. The symptoms are sometimes confused with symptoms of a similar type of arrhythmia, called atrial flutter.
If you have pre-existing heart disease (including CAD), you’re more likely to feel chest pain or discomfort from AFib. Call your doctor right away if you feel any type of chest pain. If you notice an unusually rapid or slow heartbeat along with abnormal tiredness or your normal exercise routine seems more difficult, see your doctor. AFib can be monitored and controlled.
Coronary artery disease typically develops over time. Symptoms may not occur until the blockage is significant. Reduced blood flow to the heart can cause symptoms like chest pain, shortness of breath, or fatigue.
A complete blockage can cause a heart attack. For many people, the first symptom of CAD is a heart attack.
Causes and Risk Factors
The likelihood of developing AFib increases as you age. People of European descent are more likely to have it than African American people, and more women than men have AFib (because they tend to live longer). The risk of AFib in people ages 55 and up is about 37%.
Coronary artery disease is one of the risk factors for AFib. Conditions like CAD, aging, persistent high blood pressure, diabetes, heart failure, obesity, sleep apnea, and emphysema can eventually damage the heart’s electrical system and lead to AFib. People with diabetes who are obese are more likely than people with other risk factors to get AFib.
The most common conditions associated with AFib are hypertension, diabetes, and chronic heart disease.
Other causes of AFib may include:
- Heart defect that you're born with
- Heart valve problems
- Lung diseases
- Physical stress due to surgery, pneumonia, or other illnesses
- Previous heart surgery
- Problem with the heart's natural pacemaker (called the sinus node)
- Thyroid disease such as an overactive thyroid (hyperthyroidism) and other metabolic imbalances
- Use of stimulants, including certain medications, caffeine, tobacco, and alcohol
- Viral infections
Coronary artery disease is caused by buildup of fats, cholesterol, and other substances on the inner walls of the arteries. This buildup, called plaque, causes the arteries to narrow, which slows or blocks the flow of blood.
This buildup can be caused by:
- High blood pressure
- Lack of physical exercise (inactivity)
- Smoking or tobacco use
Other risk factors of CAD may include age, alcohol intake, obesity, thyroid disease, sleep apnea, other chronic conditions (kidney disease, metabolic disease, lung disease), or a family history of heart disease.
Atrial fibrillation is not life-threatening, but it is serious and requires proper treatment. It doesn’t increase your risk of heart attack, but it does lead to other serious complications.
AFib can lead to blood clots in the heart, which increases your risk of stroke. Strokes caused by AFib complications tend to be more severe than strokes not related to AFib. If you have AFib and are older or have high blood pressure, diabetes, a history of heart failure (or previously had a stroke) or are taking certain medications (such as blood thinners), your risk of stroke is higher.
AFib can also lead to heart failure because it can weaken the heart muscle. Heart failure is a serious condition where the heart muscle can’t pump blood adequately through your body.
A weakened heart leading to heart failure also is a complication of CAD. CAD also increases your risk of developing a blood clot.
Coronary artery disease is the main cause of heart attack. Symptoms of a heart attack include:
- Chest pain or discomfort (angina)
- Weakness, lightheadedness, nausea (feeling sick to your stomach), or a cold sweat
- Pain or discomfort in the arms or shoulder
- Shortness of breath
Other heart attack symptoms include unexplained tiredness and nausea or vomiting. Women are more likely to have these other symptoms. Call 911 or a local emergency number if you experience symptoms of a heart attack.
If you have both AFib and CAD, the risk of a shortened lifespan is significantly higher. Change in lifestyle habits (quitting smoking, improving diet, increasing exercise) and controlling risk factors like blood pressure, cholesterol and diabetes are effective in treating and controlling both AFib and CAD.
For AFib specifically, treatments include:
- Medicines that control heart rhythm (like disopyramide, procainamide, and sotalol) and heart rate (like digoxin, diltiazem, metoprolol, and verapamil)
- Blood-thinning medicine to prevent clots from forming (such as aspirin or warfarin)
- Surgery and procedures (like inserting a pacemaker or catheter)
- Medicine and healthy lifestyle changes to manage risk factors
Newer medications and surgical procedures can help restore normal heart rhythm. New drugs and devices that prevent blood clots have reduced the incidence of strokes. Weight loss surgery can help reduce symptoms in obese people with AFib. Your doctor may suggest using a smartphone or smartwatch technology to track your heart rate, which can then be shared with a health care provider. Regular meditation also reduces symptoms of AFib.
For CAD, your health care provider may suggest:
- Lifestyle changes, including eating a healthy diet, increasing physical activity, reaching a healthy weight, and quitting smoking
- Medicines that treat risk factors for CAD, like high cholesterol, high blood pressure, or an irregular heartbeat
- Surgical procedures that help restore blood flow to the heart (like angioplasty, which surgically unblocks a blood vessel)