What Is Atrial Fibrillation and How Does It Happen?
Atrial fibrillation occurs when chaotic electrical signals cause the heart's upper chambers (atria) to quiver rapidly and irregularly instead of contracting normally. This creates an irregular, often fast heartbeat and allows blood to pool in the atria, forming dangerous clots.
In a normal heartbeat, electrical signals start in the sinoatrial (SA) node in the right atrium, spreading across both atria in an organized wave that causes them to contract and push blood into the ventricles (lower chambers). In AFib, multiple abnormal electrical signals fire simultaneously from various locations in the atria, overwhelming the SA node's normal pacemaker function. This causes the atria to quiver chaotically at 400-600 times per minute rather than contracting effectively. Only some of these signals reach the ventricles, resulting in an irregularly irregular heartbeat with no discernible pattern. The ventricular rate (actual pulse you feel) is usually 110-175 beats per minute if untreated, though it can be slower or faster.
AFib is classified by pattern: Paroxysmal AFib comes and goes, typically lasting less than 7 days (often less than 24 hours) before converting back to normal rhythm on its own. Persistent AFib lasts more than 7 days and requires medication or electrical cardioversion to restore normal rhythm. Long-standing persistent AFib lasts longer than 12 months. Permanent AFib cannot be converted back to normal rhythm, or attempts have been abandoned, so treatment focuses on controlling heart rate and preventing complications. Some people progress from paroxysmal to persistent to permanent over years, while others remain in one category. Understanding your AFib pattern helps determine the best treatment approach.
What Are the Symptoms and Complications of AFib?
Common symptoms include palpitations, shortness of breath, chest discomfort, fatigue, dizziness, and reduced exercise tolerance, though one-third of people have no symptoms. Major complications include stroke (five times higher risk), heart failure, cognitive decline, and reduced quality of life.
The most common symptoms are palpitations (awareness of rapid, irregular, or pounding heartbeat), which may feel like your heart is racing, flip-flopping, or skipping beats. Shortness of breath may occur during activity or even at rest. Chest pain or discomfort (angina) can result from rapid heart rate increasing oxygen demand. Fatigue and weakness may limit your ability to exercise or perform daily activities. Lightheadedness, dizziness, or fainting can occur, especially when standing quickly. Reduced exercise tolerance means activities that were previously easy now cause symptoms. Anxiety or sense of panic may accompany episodes. However, about 30% of AFib patients have no symptoms at all ('asymptomatic AFib') and are only diagnosed during routine exams or when complications develop.
The most serious complication is stroke. When the atria quiver instead of contracting, blood pools in a small pouch called the left atrial appendage, where it can form clots. If a clot breaks loose and travels through the bloodstream to the brain, it causes a stroke. AFib-related strokes tend to be more severe than strokes from other causes—they're twice as likely to be fatal, more likely to cause permanent disability, and have higher recurrence rates. AFib increases stroke risk 5-fold overall, but risk varies by individual based on other factors. Heart failure is another major complication—rapid, irregular beating reduces pumping efficiency over time, and AFib itself can cause a form of heart failure (tachycardia-induced cardiomyopathy) that may be reversible with rate or rhythm control. Other complications include cognitive decline and dementia (possibly from small, silent strokes), reduced quality of life, and increased mortality.
How Is Atrial Fibrillation Diagnosed?
AFib is diagnosed through electrocardiogram (ECG/EKG) showing characteristic irregular rhythm without distinct P waves. Diagnosis may require prolonged monitoring with Holter monitors, event recorders, or implantable loop recorders since AFib can be intermittent.
If AFib is present during an office visit, it's easily diagnosed with a 12-lead electrocardiogram (ECG) showing the characteristic pattern: irregularly irregular RR intervals (no consistent pattern to heartbeats) and absence of distinct P waves (which represent normal atrial contraction). You might also feel an irregularly irregular pulse. However, paroxysmal AFib that comes and goes may not be present during a brief office ECG. In these cases, prolonged cardiac monitoring is needed: A Holter monitor records your heart rhythm continuously for 24-48 hours while you go about normal activities. An event recorder or loop recorder is worn for weeks to months and either records continuously or is activated when you feel symptoms. Implantable loop recorders are small devices inserted under the skin that monitor heart rhythm for up to 3 years, useful for infrequent episodes.
Once AFib is diagnosed, additional tests evaluate underlying causes and stroke risk: Echocardiogram (ultrasound of the heart) assesses heart structure, function, valve problems, and checks for blood clots in the atria. Transesophageal echocardiogram (TEE) provides detailed images of the left atrium and left atrial appendage where clots form. Blood tests check thyroid function (hyperthyroidism can cause AFib), kidney function (affects medication dosing), and electrolytes. Exercise stress test may reveal exercise-induced AFib or underlying coronary disease. Chest X-ray checks for lung disease or heart enlargement. Additional tests like sleep studies for sleep apnea may be ordered based on clinical suspicion of underlying conditions contributing to AFib.
How Do You Prevent Stroke With AFib?
Blood thinners (anticoagulants) reduce stroke risk by 60-70% in AFib patients. Most people with AFib need anticoagulation based on CHA2DS2-VASc score that assesses individual stroke risk. Options include warfarin, which requires monitoring, or DOACs like apixaban and rivaroxaban.
Stroke prevention is the most important aspect of AFib treatment. The CHA2DS2-VASc score helps determine who needs anticoagulation: 1 point each for Congestive heart failure, Hypertension, Age 65-74, Diabetes, Vascular disease (prior heart attack, peripheral artery disease, or aortic plaque), and female Sex; 2 points for Age 75+ or prior Stroke/TIA. A score of 0 (men) or 1 (women, for sex alone) is low risk and anticoagulation may not be needed. A score of 1 (men) or 2 (women) indicates intermediate risk and anticoagulation should be considered based on bleeding risk and patient preference. A score of 2+ (men) or 3+ (women) is high risk and anticoagulation is strongly recommended unless bleeding risk is prohibitive.
Anticoagulation options include: Warfarin (Coumadin) is highly effective but requires frequent blood tests (INR monitoring) to ensure proper dosing, has many food and drug interactions, and takes time to adjust doses. Direct Oral Anticoagulants (DOACs)—apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran (Pradaxa), edoxaban (Savaysa)—are newer blood thinners that work as well as or better than warfarin with significantly less risk of brain bleeding, don't require monitoring, have fewer drug and food interactions, and work more quickly. Most patients are now started on DOACs rather than warfarin unless they have mechanical heart valves or severe kidney disease. All anticoagulants increase bleeding risk, so you should report any unusual bleeding, bruising, or black stools immediately. The bleeding risk is outweighed by stroke prevention benefits for most AFib patients. For people who cannot take anticoagulants due to high bleeding risk, left atrial appendage closure devices (like Watchman) can be implanted to seal off the area where most clots form.
What Medications and Procedures Treat AFib?
Treatment involves two strategies: rate control (medications like beta-blockers to slow heart rate while staying in AFib) or rhythm control (medications or procedures like cardioversion and ablation to restore and maintain normal rhythm). Blood thinners prevent stroke regardless of strategy chosen.
Rate control aims to slow the heart rate to 60-100 bpm at rest while allowing AFib to continue. Medications include: Beta-blockers (metoprolol, atenolol, carvedilol) are first-line and also help control blood pressure. Calcium channel blockers (diltiazem, verapamil) are alternatives, especially if beta-blockers can't be used. Digoxin can be added if other medications don't adequately control rate, though it's less commonly used today. Rate control is often chosen for older patients, those with persistent AFib, minimal symptoms, or significant heart disease. Studies show outcomes with rate control are similar to rhythm control for most patients.
Rhythm control aims to restore and maintain normal sinus rhythm. Approaches include: Electrical cardioversion applies a synchronized electrical shock to reset the heart's rhythm—it's 85-95% effective immediately but AFib recurs in 50% within a year without antiarrhythmic medications. Antiarrhythmic medications (flecainide, propafenone, sotalol, dofetilide, amiodarone, dronedarone) help maintain normal rhythm after cardioversion but have significant side effects requiring close monitoring. Catheter ablation involves threading catheters through veins to the heart and using radiofrequency energy or cryotherapy to destroy areas causing abnormal signals—it's 60-80% successful for paroxysmal AFib with fewer side effects than long-term antiarrhythmics. Surgical maze procedure creates scar patterns that guide electrical signals properly, typically performed during other heart surgery. Rhythm control is generally preferred for younger patients, those with symptoms significantly affecting quality of life, paroxysmal AFib, AFib triggered by a correctable condition, or new-onset AFib.
What Lifestyle Changes Help Manage AFib?
Key lifestyle modifications include limiting or avoiding alcohol, losing weight if overweight, treating sleep apnea, managing blood pressure and diabetes, regular exercise, reducing stress, avoiding stimulants, and staying hydrated. These changes can reduce AFib episodes and improve treatment success.
Alcohol is a major AFib trigger—even moderate drinking (1-2 drinks daily) increases AFib risk, and binge drinking dramatically increases risk ('holiday heart syndrome'). Many cardiologists recommend complete abstinence for AFib patients, or at most limiting consumption to 3-4 drinks per week. Weight loss significantly reduces AFib burden in overweight individuals—studies show losing 10% of body weight can eliminate AFib in some people. Sleep apnea dramatically increases AFib risk and undermines treatment—untreated sleep apnea reduces ablation success by 50%. CPAP or other sleep apnea treatments should be part of AFib management. Controlling blood pressure (target below 130/80) reduces AFib risk and recurrence. Managing diabetes helps prevent AFib and reduces stroke risk.
Regular moderate exercise (150 minutes weekly of activities like brisk walking, swimming, or cycling) improves cardiovascular health and may reduce AFib episodes. However, excessive endurance exercise (marathon running, long-distance cycling) increases AFib risk—moderation is key. Reduce stress through meditation, yoga, deep breathing, or counseling. Avoid stimulants including excessive caffeine (more than 2-3 cups daily may trigger AFib in susceptible people), energy drinks, decongestants (pseudoephedrine, phenylephrine), and illegal drugs (cocaine, methamphetamine). Stay well-hydrated. Treat underlying conditions like thyroid disease. Avoid medications that trigger AFib. These lifestyle modifications work synergistically with medical treatment to reduce AFib burden, improve symptoms, enhance treatment success, and reduce complications.
