Will an EKG always show if there is a heart problem, or if there was a heart attack?

An electrocardiogram (EKG) is a non-invasive test which records the electrical activity of the heart. It can reveal irregularities in the heart's rhythm, detect signs of damage from a prior heart attack or identify if there is any blockage in coronary arteries. While an EKG will usually show signs and symptoms of an underlying cardiac condition or previous heart attack, it may not always be conclusive. Other tests such as echocardiogram (ultrasound), cardiac MRI or stress testing may be needed to confirm the diagnosis and rule out other potential causes. In some cases, when an EKG does show abnormalities that are consistent with a prior attack, further workup including laboratory tests and imaging studies like CT scans and angiograms may also be necessary for definitive diagnosis.