1) Heart rhythm problems (heart arrhythmias) occur when the electrical impulses that coordinate your heartbeats don't work properly, causing your heart to beat too fast, too slow or irregularly. Heart arrhythmias may feel like a fluttering or racing heart and may be harmless.
2) Electrolyte imbalance. Substances in your blood called electrolytes — such as potassium, sodium, calcium and magnesium — help trigger and conduct the electrical impulses in your heart. Electrolyte levels that are too high or too low can affect your heart's electrical impulses and contribute to arrhythmia development.
3) Stopping smoking and avoiding secondhand smoke. Maintaining a healthful weight. Eating a healthful, balanced, low-fat diet. Limiting or avoiding caffeine, alcohol, and other substances that contribute to abnormal heart rhythm and other heart problems.