Complications from Arrhythmias

Many arrhythmias are self-limited and rarely cause complications. However, some can be very serious. Left untreated, they may raise your risk of the following:

  • Fainting (syncope). A heart that's not beating normally may not be able to pump blood efficiently. If inadequate blood reaches the brain, it can cause a fainting spell, which may lead to injury.
  • Stroke. Certain arrhythmias, such as atrial fibrillation, may allow small blood clots to form in your heart. If these clots break loose and are carried via your bloodstream to your brain, they could cause a stroke. Your risk of stroke depends on your age, the type of arrhythmia you have and whether you have any other cardiovascular risk factors for stroke, such as high blood pressure.
  • Congestive heart failure. A heart that beats very fast for a prolonged period of time may become permanently weakened — a condition known as congestive heart failure.
  • Sudden death. Ventricular arrhythmias in people with structural heart disease — such as a weakened heart muscle from a previous heart attack — may lead to death. However, in people with healthy hearts, life-threatening arrhythmias are exceedingly rare.

In general, arrhythmias are more serious if you have other heart problems.