ECGAn electrocardiogram is a painless, noninvasive way to help diagnose many common heart problems in people of all ages. It is used to determine or detect:<ul style="list-style-type:circle"> Abnormal heart rhythm (arrhythmias)If blocked or narrowed arteries in your heart (coronary artery disease) are causing chest pain or a heart attackWhether you have had a previous heart attackHow well certain heart disease treatments, such as a pacemaker, are workingYou may need anECGif you have any of the following signs and symptoms:<ul style="list-style-type:circle"> Chest painDizziness, lightheadedness or confusionHeart palpitationsRapid pulseShortness of breathWeakness, fatigue or a decline in ability to exercise If you have an irregular heartbeat or heart palpitations, but an ECG didn’t detect anything, a cardiac monitor can help diagnose the problem. You wear the Holter monitor while you do your daily activities. Your provider discusses the results with you.