Final answer:
Creatine phosphokinase (CPK), specifically the CPK-MB isoenzyme, is known to be the cardiac marker that peaks the fastest following a myocardial infarction, making it vital for early diagnosis and treatment of heart attacks.
Step-by-step explanation:
The student asked which cardiac marker peaks fastest when diagnosing a myocardial infarction, commonly known as a heart attack. Creatine phosphokinase (CPK), specifically the isoenzyme CPK-MB, is known to increase quickly in the blood plasma following a heart attack and is considered a primary marker for such an event. CPK levels can rise within a few hours of a heart attack and maintain elevated concentrations for 1-2 days. This enzyme is one of the first indicators of myocardial infarction and its concentration increases rapidly, which can be 10 times more than the normal level after the first heart attack.
Another important enzyme that increases during myocardial infarction is the H4 or LDH₁ isoenzyme form of lactate dehydrogenase; however, its peak levels are maintained in the plasma for 6 days after the heart attack, indicating it does not peak as quickly as CPK. It is crucial to rapidly identify the increase in cardiac markers to diagnose and treat a heart attack effectively, which can save lives and limit heart damage.