Atrial Fibrillation / Atrial Flutter

Information from American Heart Association for more extensive information.

Atrial fibrillation and atrial flutter are very common arrhythmias. Tens of millions of people; 13% of population over 65 years old common are affected. While not the same they are closely related and like “brothers or cousins” of one another. Both arrythmias come from abnormal electrical discharges in the top heart chambers (atria). They go very fast (up to 300 beats per minute (bpm)) and though slowed through the heart’s electrical relay (AV node) still make the heart beat faster than normal.

Basic heart electricity: In the top right heart chamber (atrial) the heart’s main electrical pacemaker (sinus node) sends electricity down special conductive pathways until they reach the relay station (AV node). Here the signal is sent down more special pathways into the lower heart chambers (ventricles) where they branch to make both the right and left side beat together.

In a baseball analogy the picture throws to catcher at a steady rhythm (normal sinus rhythm). Now if the entire infield also started throwing to the catcher he will experience many baseballs coming fast and irregular and have difficulty keeping up (atrial fibrillation). Atrial flutter is similar but more rhythmic and less irregular.

We fix atrial fibrillation the same way you would fix this analogy, either stop the infield from throwing baseballs or at least slow them down so the catcher can keep up.

Atrial Fibrillation (A. fib):

Electrical current makes the heart pump. So if you have an electricity problem, you may also have a pump problem. Classically atrial fibrillation causes the heart to beast fast (between 100-200 bpm) and irregularly. When too fast the heart can’t refill with blood in time and so less blood is pumped out. Even though its going faster, less blood pumping out of the heart to the brain causing dizziness or passing out (syncope).

The second problem is this irregular electrical current makes the top chambers of the heart quiver or tremor instead of rhythmic pumping. Blood can pool in certain areas of the heart (left atrial appendage) and form a blood clot. If this clot falls into the lower heart chamber it is pumped to the brain causing a stroke (about 1/4 strokes come from A. fib).

Medical treatment of A fib addresses both the electricity / pump issues and stroke risk.

A. fib treatment:

1. Electrical:
   • Get rhythm back to normal:
   • Give medications which can help the heart switch from A.fib to normal rhythm.
   • Temporarily reset the heart through an electrical shock (direct current cardioversion).
   • Perform a procedure inside the heart (ablation) which “permanently” fixes atrial fibrillation (ablation have about 85% success rate)
   • Use a pacemaker to take over the electrical control of the heart.
2. Reduce stroke risk
   • Give blood thinners which reduce the risk blood pooling in the heart will form a clot and cause a stroke.
   • The use of blood thinners is very individualized to the patient. Their age, other health problems, risk of bleeding, chance it will reduce stroke risk are all considered.
   • There are calculators available to help calculate the risk vs benefits: Overall blood thinners reduce the relative risk of stroke 50-66%. Example: if you had a 9% risk of stroke blood thinners reduce it to 3-5%; NOT you had 100% chance of stroke and medications make it 33%.
     • ACC Anticoagulation Calculator
     • CHADSVASC Calculator
     • HASBLED Calculator
   • Common blood thinners:
   • Pills: warfarin (Coumadin), apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran (Pradaxa)
   • IV or injectable: enoxaparin (Lovenox), heparin
   • Non-medicine: Watchman is a device implanted to the top chamber of the heart (left atrial appendage) which reduces the risk of stroke from A.fib without blood thinners; reserved for those whose risk of bleeding is too great with medication.

Atrial Flutter – very similar to A.fib. The pathway of the electrical signal is different. It carries a risk of stroke and is treated similar to A. fib and thus from a patient’s perspective can be considered different sides of the same coin.

Note: There are other blood thinners like clopidogrel (Plavix) or ticagrelor (Brillinta) which are for the heart or strokes but these DO NOT treat A.fib or A. flutter. Do not presume your blood thinner will reduce stroke risk in A. fib without talking with your doctor.