When your heart's natural pacemaker isn't working properly, your heart can't perform as efficiently as it should. This can lead to a very slow heart rate, which may cause fainting.

In rare cases, long periods of slow heart rate or fast heart rate can keep your heart from pumping enough blood to meet your body's needs — a condition called heart failure.

If you have a type of sick sinus syndrome called bradycardia-tachycardia syndrome, you also may be at a higher risk of developing a blood clot in your heart that may lead to a stroke. That's because the fast heart rhythm that occurs in bradycardia-tachycardia syndrome is often atrial fibrillation.

Atrial fibrillation is a chaotic rhythm of the upper chambers of the heart that can cause blood pooling in the heart. Blood clots are more likely to form when blood flow through the heart is altered in any way. A blood clot can break loose and travel to the brain, causing a stroke.

May. 13, 2014

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