Final answer:
The first cardiac marker to increase in blood after a myocardial infarction (MI) is creatine phosphokinase (CPK), specifically the CPK-MB isoenzyme.
Cardiac troponins also rise early and are the gold standard for detecting cardiac injury. An electrocardiogram (ECG) can also diagnose an MI through changes in the ST and Q segments.
Step-by-step explanation:
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow is obstructed to a part of the heart, causing damage and resulting in the release of certain biomarkers.
Among the first enzymes to increase in the blood after a heart attack is creatine phosphokinase (CPK), specifically the CPK-MB isoenzyme, which is more specific to the heart and rises within a few hours following an MI.
In addition to CPK-MB, cardiac troponins are another marker that increases early after the onset of an MI and are considered the gold standard for the detection of cardiac muscle cell injury.
An MI can also be diagnosed through changes observed in an electrocardiogram (ECG), revealing alterations in the ST and Q segments, which may indicate a STEMI or non-STEMI. An elevation of the ST segment is often seen in patients with an acute MI, suggesting an ongoing heart attack.
Other diagnostic methods can include echocardiography or cardiac magnetic resonance imaging (MRI) to visualize the heart structure and monitor its function post-infarction.
It's important to assess multiple markers since various cardiac enzymes and proteins are released at different times, offering a timeline for the onset of myocardial infarction and assisting in guiding treatment decisions.