There are several causes of an irregular heart rate, or arrhythmia, but primary ones include coronary heart disease and medications, according to Healthline. Coronary heart disease is often the most serious cause of arrhythmia, as it results from blocking of arteries by cholesterol and other deposits.
Stimulants, such as caffeine and amphetamines, cause irregular heartbeats at times, reports Healthline. Beta blockers used to treat high blood pressure are an additional medicinal culprit. Other possible causes include heart muscle changes following trauma and heart abnormalities. Some people experience irregular heart rates while recovering from surgery. Low potassium and low electrolytes, along with various other health conditions, can contribute as well.