21.05.2021 – 16:47
Heart attacks usually cause symptoms such as chest pain, breathing problems and dizziness. It is also possible to have a silent heart attack and experience no symptoms at all.
An electrocardiogram (ECG) is a test that measures the electrical activity of the heart. Abnormal patterns of activity suggest that part of the heart may have been damaged, such as by a heart attack.
In this article, we will examine how accurate ECGs are for diagnosing a previous heart attack, if they can predict future heart attacks, and other tests to assess the health of your heart.
How far can an ECG show a heart attack?
An ECG could potentially reveal that you had a heart attack years ago without knowing it. Abnormal electrical patterns during the test suggest that part of the heart may have been damaged by a lack of oxygen.
Not all heart attacks produce obvious symptoms. If you have had a silent heart attack, you may not know it happened until you have an imaging test like ECG, MRI, CT scan or EKO ultrasound.
An ECG is a tool that doctors use to find evidence of previous heart attacks, but is best used when combined with other diagnostic techniques such as blood tests and imaging. It is relatively common for ECG results to give a false positive.
One study measured the accuracy of an ECG for diagnosing a previous heart attack compared to a cardiac MRI. The researchers found that the ECGs had:
Poor sensitivity. The ECG only correctly identified a previous heart attack 48.4 percent of the time compared to an MRI.
Good specifics. The ECG accurately identified that no previous heart attack had occurred 83.5 percent of the time compared to MRI.
Positive predictive accuracy. People with ECG scores that suggested they had a heart attack had a 72 percent chance of having had a heart attack.
Negative predictive accuracy. People with ECG results who suggested they did not have a heart attack had a 64.2 percent probability of not having had a heart attack.
Poor sensitivity and modest negative predictive accuracy of ECG findings suggest that ECG alone may not be the best way to diagnose a previous heart attack.
Can an ECG predict a heart attack in the future?
An ECG can predict a future risk of heart attack by detecting abnormalities in the electrical activity of the heart.
A 2019 study found that ECG-based risk outcomes for cardiovascular disease are as good as – or sometimes better than – risk outcomes based on a patient’s history.
In another 2019 study, researchers found that people with atherosclerotic disease or multiple risk factors for heart attack often had abnormal ECG readings.
Using ECG results alone is not an effective predictor of a future heart attack in low-risk individuals. It is possible to have a heart attack despite a normal ECG reading.
One limitation of the ECG is that it may not show an asymptomatic blockage in the artery that could put you at risk for a heart attack in the future. ECGs are best used as a predictor of a future heart attack in combination with other tests.
Researchers at UT Southwestern Medical Center found evidence that the results of a combination of five tests better predict the risk of developing heart disease compared to assessing blood pressure, cholesterol, diabetes and smoking history.
The five tests were:
* Standard ECG to provide information about heart muscle thickening
* Coronary calcium scan to identify plaque buildup in the arteries of the heart
* C-reactive protein blood test to measure inflammation
* NT-proBNP blood test to measure stress on the heart
* Troponin T blood test to measure heart damage
It is still not clear how effective ECGs are in identifying the future risk of heart attack.
If you think you may have had a heart attack, it is important to seek medical attention immediately. The sooner you get the right treatment, the better it is for your health.
