Despite severe symptoms, the results of tests to investigate chest pain are often normal in patients with acute coronary syndrome. Obvious signs are more commonly seen in patients with a definite heart attack than in those with unstable angina. In other words abnormal changes detected by an ECG often come and go with the pain, which can make it difficult diagnose the cause of the pain.
The 12-lead ECG is the most important test in patients with suspected acute coronary syndrome. The ECG provides essential information and should be performed as soon as possible, preferably within 10 minutes of chest pain coming in. The doctors and specialist nurses will be looking for specific, often subtle, ECG changes that will help them diagnose whether a patient has had a heart attack or unstable angina. It is worth noting that an ECG result that looks normal does not necessarily mean that there is no acute coronary syndrome. Of the patients with symptoms consistent with ischemia (shortage of oxygen-rich blood to the heart) who have a normal ECG reading, approximately 4% will be found to have unstable angina and up to 6% will have evidence of damage to the heart . It is for this reason that the medical team do not rely solely on the ECG for diagnosing acute coronary syndrome.
Blood tests play a vital role in helping to diagnose acute coronary syndrome. There are now special blood tests that detect specific enzymes that are released into the blood stream when the heart muscle is damaged, either as a result of a heart attack or severe unstable angina. One such test is the troponin blood test. This test is very specific and sensitive to the cardiac muscle and helps indicate the level of damage caused by a heart attack or severe unstable angina. The troponin test is usually ordered when a patient first goes into hospital and is then repeated six hours and 12 hours after that. Troponin levels are normally very low, so even a slight increase in the troponin level can indicate damage to the heart. Troponin levels remain higher than normal for up to seven to 10 days after a heart attack. However, raised troponin levels should not be used alone to diagnose or rule out a heart attack. The diagnosis of acute coronary syndrome still relies on the judgment of a doctor after a careful combination of clinical tests, experience and instinct.
Copyright © 2010 University Hospitals of Leicester NHS trust. All rights reserved - feedback | terms & conditions | about us | contact us
Website design by Kinetic ICT Solutions Ltd