If you’ve got a-fib you’ve probably wondered just how serious the condition has to be before there’s a danger that blood clots will form and stroke will become an issue.
This isn’t an exact science, but there are certainly some contributing factors that let doctors ascertain the risks.
How long does atrial fibrillation have to last to cause a blood clot that can result in a stroke? The best answer is we don’t fully know. What we do know is that if you have atrial fibrillation that requires an electrical shock to the heart, called a cardioversion, to make the heart beat normal again, then your risk of having a stroke is higher immediately afterward and for the next 2-4 weeks. This higher risk we believe occurs because as the heart beats normally again, clots that were already formed can become dislodged by the return on heart contractions and cause a stroke.
When an atrial fibrillation episode starts returning the heart to normal is the first priority. The doctors may then either prescribe blood thinners or go looking for clots with a procedure called a transesophageal echocardiogram. But they can’t use the a-fib episode itself as a guide. Instead, they look for other stroke risk factors to make the determination.
This is tricky though. Often, doctors are only able to diagnose a-fib after there’s already been a stroke.
That’s why products like the new 3-year heart monitor represent such an important breakthrough. They may allow doctors to catch a-fib after the patient presents with other symptoms until waiting for a stroke to occur.
Basically, however, if you’ve got a-fib you’ve got some risk of stroke, period. There’s no magic lower “amount” of a-fib that makes stroke less likely, though more frequent episodes can, of course, make stroke more likely. If you’ve got a-fib stroke prevention needs to be your priority.