What is happening in the heart
Normally, each heartbeat starts in the sinus node — a small cluster of cells in the upper-right chamber of the heart — and travels in an orderly wave that squeezes the atria, then the ventricles. In atrial fibrillation, the atria stop firing in that orderly way. Instead, many small electrical wavelets fire chaotically — often more than 400 times per minute. The atria don’t really squeeze; they quiver.
The AV node acts as a gatekeeper between the atria and the ventricles. It blocks most of those chaotic signals, but a fraction get through, and the ventricles end up beating irregularly — sometimes fast, sometimes at a normal rate.
Why it matters
Two main reasons:
- Stroke risk. When the atria don’t contract well, blood can pool — especially in a small pouch called the left atrial appendage — and a clot can form. If a clot travels to the brain, it causes a stroke. This is the single most important reason we treat AFib aggressively.
- Symptoms and heart function. Some people don’t feel AFib at all. Others feel palpitations, fatigue, breathlessness, or chest discomfort. Long-standing fast AFib can also weaken the heart muscle (called tachycardia-mediated cardiomyopathy), which usually improves once the rhythm is controlled.
How we classify it
- Paroxysmal — comes and goes on its own, episodes lasting less than 7 days.
- Persistent — lasts longer than 7 days; usually needs a cardioversion or rhythm-control plan to convert back.
- Long-standing persistent — continuous for more than a year, but rhythm control still being attempted.
- Permanent — a shared decision to stop trying to restore normal rhythm and focus on rate control and stroke prevention.
The classification matters because earlier, more episodic AFib tends to respond better to ablation than long-standing AFib.
How we diagnose it
A standard 12-lead ECG is enough when AFib is happening at the moment we record it. When AFib is intermittent, we use longer monitors: a 24–48-hour Holter, a 2-week patch monitor, a mobile cardiac telemetry monitor, or — for very infrequent episodes — an implanted loop recorder. Smartwatches and consumer ECG devices are increasingly useful for catching episodes at home.
How we treat it
We think about three pillars:
- Stroke prevention. Based on individual risk (we use a calculator called CHA₂DS₂-VASc), most AFib patients benefit from a blood thinner. For patients who can’t take a blood thinner long term, a left-atrial appendage closure device (such as WATCHMAN) is an option.
- Rate control. If the ventricles are beating fast, we slow them with medications like beta-blockers or non-dihydropyridine calcium channel blockers.
- Rhythm control. Restoring and maintaining normal rhythm. Options include antiarrhythmic medications, cardioversion (a brief electrical reset), and catheter ablation — which has become a first-line option for many patients, particularly with paroxysmal AFib.
What to expect at your visit
We’ll talk through your symptoms, look at any monitoring data, and tailor a plan to your goals. There’s almost always more than one reasonable path. Lifestyle factors — alcohol, sleep apnea, weight, blood pressure — matter a lot and we’ll discuss those too.