The Full form of PAC is Premature Atrial Contraction. PAC is a cardiac dysrhythmia characterized by premature heartbeats originating in the atria. They are common, and most of the time, don’t need treatment. The heart has four chambers. The upper two are the “atria.” If your heart’s electrical system triggers the early or extra beat in the atria, the result is a Premature Atrial Contraction. A similar condition – Premature Ventricular Contraction (PVC) – starts in the lower chambers, called “ventricles,” of your heart. Any time when heart shifts out of its usual rhythm, doctors call it an “arrhythmia.” There are lots of different kinds, including PACs. When people have a PAC, they might notice a flutter in their chest, fatigue after exercise, shortness of breath or chest pain and lightheadedness or dizziness. Doctors don’t always know the cause. But these things can make PACs more likely; Pregnancy, High blood pressure, heart disease, or hyperthyroidism, Stress or fatigue, Caffeine, Alcohol, Smoking, Cold or hay fever medicine, Asthma medicine or Dehydration. Usually, Premature Atrial Contractions (PACs) have no clear cause and no health risks. In most cases, PACs aren’t a sign of heart disease and just happen naturally.