18. “Can I have A-Fib when my heart rate stays between 50-60 BPM? My doctor tells me I have A-Fib. I usually have episodes which last under an hour, but I don’t always have a rapid heart rate. Sometimes when I lie down to go to sleep, an episode comes on. When I check my heart rate, it’s irregular but not rapid.”
In some cases it’s possible to have A-Fib and still have what appears to be a regular heart rate. Your atria can be fibrillating, even though your heart doesn’t beat rapidly. How can that be? When you take your pulse, you’re counting the beats of your ventricles, not your atria. So, your atria can be fibrillating, but your heart beat appears normal.
When listening to your heart through a stethoscope—you’re listening to your ventricles, not your atria.
Let’s say, for example, that you have A-Fib and your left atrium is fibrillating (quivering, beating) around 300 times a second. But in your case, your AV Node circuitry may be functioning very well, like a gatekeeper, to minimize the rate at which your atrial A-Fib pulses affect your heart rate (i.e., ventricular beats).
In another instance, some people have “silent” A-Fib (A-Fib with no symptoms) and appear to be in normal sinus rhythm (NSR). Their Atrial Fibrillation may only be discovered when they have a routine physical exam that includes an EKG. We don’t know enough about silent A-Fib, but untreated, it can kill you. Many people who suffer strokes are later found to have silent A-Fib.
Older people sometimes can have a slower form of A-Fib which can look like normal sinus rhythm, but they still have symptoms such as fatigue-tiredness and difficulty with exertion. Some forms of Atrial Flutter (4:1 ratio or slower) may also look like a normal heart rhythm.
But for most patients, their Atrial Fibrillation appears as an irregular and faster heart rate.