When a heart attack, also known as myocardial infarction, is suspected, immediate hospitalization is crucial. Typically, you will be admitted to either an acute cardiac care unit (ACCU) or directly to the cardiac catheterization unit. This rapid admission allows for prompt diagnosis confirmation and the immediate commencement of necessary treatment. But what specific tests are employed by medical professionals to definitively diagnose a myocardial infarction? This article will explore the key diagnostic tests used to confirm a heart attack.
Electrocardiogram (ECG)
An electrocardiogram, commonly referred to as an ECG or EKG, is a cornerstone diagnostic tool when a heart attack is suspected. Ideally, an ECG should be performed within ten minutes of hospital admission. This rapid assessment is vital because the ECG provides immediate insights into the electrical activity of your heart.
Each heartbeat generates minute electrical impulses. An ECG machine meticulously records these signals, displaying them on paper or a digital screen. This visual representation enables doctors to evaluate the heart’s functionality in real-time, identifying any abnormalities indicative of a heart attack.
The ECG procedure is painless and swift, typically taking around 5 minutes to complete. During the test, small, flat, adhesive electrodes are attached to your arms, legs, and chest. These electrodes are connected via wires to the ECG machine, which then captures and records the heart’s electrical activity.
The ECG plays a critical role for several reasons in the context of a suspected heart attack:
- Confirmation of Heart Attack Diagnosis: Characteristic patterns on the ECG tracing can strongly indicate a myocardial infarction.
- Determination of Heart Attack Type: The ECG helps differentiate between various types of heart attacks, such as STEMI and NSTEMI, which is crucial for guiding the most effective treatment strategy.
Blood Tests: Cardiac Markers
Damage to the heart muscle during a heart attack results in the release of specific proteins into the bloodstream. These proteins, known as cardiac markers, are not typically present in significant amounts unless heart muscle injury has occurred.
If a heart attack is suspected, blood tests to detect these cardiac markers are essential. A blood sample will be drawn and analyzed in the laboratory to measure the levels of these proteins.
The most frequently measured cardiac marker is cardiac troponin. Elevated troponin levels are highly sensitive and specific indicators of heart muscle damage. The magnitude of troponin elevation can also provide insights into the extent of heart damage and help in classifying the type of heart attack.
Types of Heart Attack and Diagnostic Markers
Heart attacks are categorized based on ECG findings, specifically changes in the ST segment, and the presence and level of cardiac troponin in the blood. Understanding these classifications is important for diagnosis and treatment.
Acute Coronary Syndrome (ACS)
Myocardial infarction is a form of acute coronary syndrome (ACS). ACS encompasses conditions involving a sudden reduction of blood flow to the heart. In the case of a heart attack, this reduced flow is due to a significant blockage in the coronary arteries.
The primary types of ACS include:
- ST-segment elevation myocardial infarction (STEMI): Characterized by a complete or near-complete blockage of a coronary artery.
- Non-ST-segment elevation myocardial infarction (NSTEMI): Involves a partial blockage or a more subtle form of coronary artery obstruction.
- Unstable Angina: While not technically a heart attack where heart muscle damage occurs, it is a serious condition with similar symptoms and a high risk of progressing to a heart attack.
ST-Segment Elevation Myocardial Infarction (STEMI)
A STEMI heart attack is characterized by a prolonged and severe interruption of blood supply to a region of the heart. This leads to substantial damage to the heart muscle. Diagnostically, STEMI is identified by specific characteristic changes observed on the ECG, namely ST-segment elevation.
STEMI is a critical medical emergency requiring immediate intervention to restore blood flow to the blocked artery.
Non-ST-Segment Elevation Myocardial Infarction (NSTEMI)
NSTEMI is another type of heart attack resulting from reduced blood supply and subsequent heart muscle damage.
In NSTEMI, the ECG does not show the ST-segment elevation seen in STEMI. However, blood tests will reveal elevated cardiac markers, such as troponin, confirming heart muscle damage.
Like STEMI, NSTEMI is a medical emergency. Without prompt treatment, it can escalate into a STEMI.
Unstable Angina
Unstable angina presents with heart attack-like symptoms, such as chest pain. However, in unstable angina, diagnostic tests, including ECG and blood tests for cardiac markers, do not show definitive evidence of heart muscle damage.
Despite the lack of detectable heart damage, unstable angina signifies a severely restricted blood supply to the heart. Individuals with unstable angina are at a significantly elevated risk of experiencing a full-blown heart attack.
Additional Diagnostic Tests
While ECG and blood tests are the primary tools for confirming a heart attack diagnosis, other tests may be utilized to evaluate the heart’s condition and identify potential complications. However, given the emergent nature of heart attacks, these additional tests are typically performed after initial treatment has commenced and the patient’s condition has stabilized.
Chest X-ray
A chest X-ray can be valuable when the diagnosis of a heart attack is uncertain and other conditions might be responsible for the symptoms. For instance, it can help rule out a pneumothorax, a condition where air becomes trapped between the lung layers.
Furthermore, a chest X-ray can detect complications arising from a heart attack, such as pulmonary edema, which is fluid accumulation in the lungs.
Echocardiogram
An echocardiogram is an ultrasound scan of the heart. It employs sound waves to create detailed images of the heart’s structures and function.
Echocardiography is useful in pinpointing the specific areas of the heart that have sustained damage and assessing the impact of this damage on the heart’s overall pumping efficiency.
Coronary Angiography
Coronary angiography is an invasive procedure that helps visualize the coronary arteries. It is performed to determine if there are blockages or narrowings in these arteries and, if so, to precisely locate them.
During coronary angiography, a thin, flexible tube called a catheter is inserted into a blood vessel, usually in the groin or arm. Guided by X-ray imaging, the catheter is advanced to the coronary arteries.
A contrast agent, a special fluid visible on X-rays, is injected through the catheter. By observing the flow of this contrast agent through the heart and coronary arteries, cardiologists can identify the sites of any blockages or narrowings. This information is crucial for guiding treatment decisions, such as angioplasty or bypass surgery.
To learn more about interventions following a heart attack, explore resources on heart attack treatment.
Page last reviewed: 13 July 2023
Next review due: 13 July 2026
