Why a rapid heartbeat increases your risk for stroke

Atrial fibrillation (AFib) and atrial flutter are two common arrhythmias, or abnormal heart rhythms. Both conditions result from abnormal electrical signals in the heart's upper chambers, or atria. These two conditions can also share certain symptoms, triggers and complications but they’re not the same and may respond differently to treatment.

Understanding the differences

Both AFib and atrial flutter are types of supraventricular tachycardia. Supraventricular means above the ventricles and tachycardia is the word doctors use to describe a rapid heartbeat, explains James Davenport, MD, a cardiac electrophysiologist affiliated with Kendall Regional Medical Center in Miami, Florida.

When your heart is beating properly, the atria receive blood while the ventricles, the lower chambers of the heart, pump it back out to the rest of your body. During AFib, the most common arrhythmia, chaotic electrical signals cause the atria to quiver, resulting in a rapid and irregular heart rhythm.

By contrast, atrial flutter occurs when rapidly looping electrical signals cause the atria to beat too quickly. Unlike AFib, the electrical signals that cause atrial flutter occur in an organized, predictable pattern. So, your heartbeat is fast but usually steady. Atrial flutter, however, is often linked with AFib.

Understanding the similarities

Both AFib and atrial flutter may come and go or remain constant. Some people may be affected by both conditions. In some cases, these arrhythmias cause similar symptoms and share certain risk factors.

Some people with atrial flutter may not notice any warning signs while others experience:

• Heart palpitations
• Rapid pulse
• Shortness of breath
• Chest pain or pressure
• Dizziness
• Fainting
• Fatigue

These same symptoms are common among people with AFib.

Both AFib and atrial flutter tend to occur more frequently in older people, those who’ve had heart surgery and people with chronic lung disease, diabetes or preexisting heart disease, including heart failure, heart attack, high blood pressure and congenital heart disease. Heavy or binge drinking and an overactive thyroid also increase the risk for these abnormal heart rhythms.

In some cases, the consequences of both AFib and atrial flutter can be serious, Dr. Davenport cautions. “When your heart beats too fast, you can feel dizzy or faint, but the most toxic result of either one is a stroke,” he says.

During AFib, blood collects in your atria, where it can form blood clots. If a blood clot breaks free, it can travel to your brain, blocking blood flow and causing a stroke. Blood clots can also form during atrial flutter. Similarly, atrial flutter makes it more difficult for the heart to pump blood as well as it should. When the heart is not pumping blood effectively, it increases the risk for clots.

Both AFib and atrial flutter also increase the risk for heart failure, which incidentally, can also lead to AFib.

Identifying fast or chaotic heartbeats

If you are experiencing symptoms of AFib or atrial flutter, your healthcare provider (HCP) will first conduct a thorough medical history and physical exam. This assessment may also help identify possible underlying health issues or triggers that could cause palpitations or other symptoms of a fast or irregular heartbeat, such as exercise, intense emotions or alcohol consumption.

Certain tests are also used to help diagnose irregular heart rhythms, including an electrocardiogram (ECG). This test records your heart’s electrical impulses. Atrial flutter, for example, makes a very specific "sawtooth" pattern on an ECG. Your doctor may ask you to wear a portable monitor, such as a Holter monitor, which can help detect any abnormal heartbeats over a longer period of time.

You may also undergo an echocardiogram—an ultrasound of the heart that helps doctors examine the heart valves and identify blood clots in the upper chambers of the heart. In some cases, a blood test may also be ordered to check for an overactive thyroid gland, which can lead to AFib.

If you are diagnosed with atrial flutter or AFib, your doctor has two main goals: to control the abnormal rhythm and to reduce your risk of stroke.

Managing symptoms and risks

Most people with unresolved atrial flutter and AFib should be taking anticoagulants, or medications to prevent blood clots and reduce their risk of stroke, Davenport advises.

Lifestyle changes can also help manage both AFib and atrial flutter and reduce the risk for stroke. These include:

• Getting regular exercise
• Not smoking
• Controlling high blood pressure
• Following a heart-healthy diet
• Limiting caffeine and alcohol intake
• Maintaining a healthy weight

But these two abnormal heart rhythms, which share many similarities, often respond differently to other treatment options, Davenport points out.

For those with AFib, a range of different drugs, including anti-arrhythmic medications as well as beta blockers and calcium channel blockers, could help slow the heart rate and ease symptoms. “Atrial flutter is more difficult to manage with medication,” Davenport says.

When medications and lifestyle adjustments alone aren’t effective, certain therapies may be used to restore a normal heart rhythm for those with either AFib or atrial flutter, including electrical cardioversion. During this procedure, relatively low levels of electricity are used to “shock” the heart back into a steady rhythm.

When cardioversion fails, another treatment option for both conditions is catheter ablation—a minimally invasive procedure that uses energy, such as extreme heat or cold, to destroy the cells and create scar tissue, which blocks the abnormal electrical signals.

This treatment, however, tends to be more effective in treating atrial flutter than AFib since the electrical signals that trigger atrial flutter spin around in a loop. “It’s more of a straight shot,” Davenport says. “It’s usually a one and done.” When using ablation to treat AFib, on the other hand, it’s more difficult to locate and destroy all the trouble spots triggering the abnormal electrical signals.