August 14, 2012
A new test could help emergency departments rule out (or rule in) heart attacks faster, according to a new study. The test is called high-sensitivity cardiac troponin. It detects cardiac enzymes called troponins. High troponin levels in the blood are a sign of damage or injury to the heart. And this could signal heart attack. The Swiss study took place from April 2006 to June 2009. It examined close to 900 patients who visited the ER with chest pain. Half of the patients were evaluated using the new testing method. That new method included gauging the troponin level when they arrived and then again an hour later. Using this method, the researchers ruled out heart attack in 60% of patients. They found evidence of heart attack in 17%. And the other 23% of patients were observed and monitored further. Thirty-day survival rates were 99% for those who did not have a heart attack, 98% for those placed under observation, and 95% for those who had a heart attack. The journal Archives of Internal Medicine published the study. HealthDay News wrote about it Aug. 13.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
That dull burning in your chest doesn't seem to be going away. Or perhaps it's getting worse. Is it a heart attack, or something else?
Millions of people and thousands of doctors face this question every year. What's the problem? Chest pain that can feel just like a heart attack can be caused by multiple conditions. Acid reflux with spasm of the esophagus and panic attack are two common examples.
More than 6 million Americans with chest pain seek care in hospital emergency departments every year. Less than 20% of them have a heart attack or unstable angina. Unstable angina is a warning sign that a heart attack may happen soon.
A small percentage will have another potentially life-threatening problem, such as pulmonary embolism (a blood clot in the lungs) or aortic dissection (a tear in the inner layer of the aorta). Some are diagnosed with stable angina that is important to recognize but not immediately dangerous. The hearts of people with stable angina don't get as much oxygen-rich blood as they need during exercise or emotional stress.
But most of the 6 million have a condition unrelated to the heart or arteries.
The other tricky problem with heart attacks is that different people experience them in different ways. Some have classic chest pain. Others have jaw pain or back pain. Still others, especially women, become breathless, extremely fatigued (tired) or nauseated.
Doctors mainly use 2 tests to determine who is, and who isn't, having a heart attack. They are the electrocardiogram (ECG) and a blood test called cardiac troponin. Troponin gets released into the blood stream when heart muscle cells are injured.
However, within the first few hours of a heart attack, both the ECG and troponin blood test can be normal. So, if there is any question of a possible heart attack, patients are observed and closely monitored for 12 - 16 hours. During that time, they get retested with ECGs and cardiac troponins looking for ECG changes and/or a rise in the troponin level.
More recently a new troponin test has become available that is much more sensitive. This test, called a high-sensitivity troponin test, can detect heart damage at a much earlier time from onset of symptoms.
In the August 13th issue of Archives of Internal Medicine, researchers report their results of a new accelerated diagnostic strategy for heart attack. They used ECGs as doctors always do. They also used the new high-sensitivity troponin test.
Instead of waiting 6 to 8 hours between tests, they did a high-sensitivity troponin blood test when the patient arrived and again in just 1 hour. If the test result was normal and the troponin did not increase from the first to the second test, the patient could be safely diagnosed as not having a heart attack.
What Changes Can I Make Now?
There are so many reasons you might delay calling for help.
Chest pain is only one of the possible signs of an impending heart attack. Call 911 or your local emergency number right away if you have:
What Can I Expect Looking to the Future?
The findings in this study will need to be confirmed in additional studies before this strategy to "rule out" a heart attack will be widely adopted.