There's nothing romantic about your heart skipping a beat, whatever the poet might say. All hearts flutter from time to time. These arrhythmias are generally harmless and may have no discernable cause at all. But if it happens frequently or is accompanied by other symptoms (like shortness of breath), the sight of your sweetie might not be to blame.
Atrial fibrillation (AF), the most common affliction of the heart, affects over 2 million Americans. Those with the disorder have hearts whose upper chambers beat irregularly and too rapidly. AF can cause blood clots and is linked to one-third of all strokes in those over 65. It arises not from swooning or sneezing, but usually from infections or other heart disease.
There may also be a link between AF and alcohol consumption, excessive caffeine, stress and drug use. In some cases, a heritable genetic defect causes AF.