A client with unstable angina is scheduled for coronary artery bypass grafting (CABG). The client asks the nurse about the purpose of this surgery. How should the nurse respond?

A) This choice is incorrect because myoglobin is a cardiac biomarker that may be elevated in MI, but it lacks specificity and can also be elevated in other conditions like skeletal muscle injury.

B) This choice is incorrect because C-reactive protein (CRP) is an inflammatory marker and is not specific to MI. It may be elevated in various inflammatory conditions.

C) This choice is incorrect because brain natriuretic peptide (BNP) is a biomarker associated with heart failure and is not specific to diagnosing MI.

D) This choice is correct. Troponin is the most specific biomarker for diagnosing MI. Elevated troponin levels in the blood indicate cardiac muscle damage, making it a reliable marker for myocardial infarction. Troponin levels rise shortly after the onset of MI and remain elevated for several days, making it valuable in both early and delayed MI detection.

A) This choice is correct. The sudden onset of chest pain lasting for 30 minutes is a typical clinical manifestation of myocardial infarction (MI). The duration and intensity of chest pain are important indicators that suggest an acute cardiac event.

B) This choice is incorrect because chest discomfort lasting for a few days may be more characteristic of unstable angina, not an MI. Unstable angina is also a serious condition that requires prompt medical attention, but it is not synonymous with MI.

C) This choice is incorrect because chest pain that comes and goes, lasting only a few seconds at a time, is not typical of an MI. Such symptoms may indicate other non-cardiac conditions or stable angina.

D) This choice is incorrect because a similar episode of chest pain a few months ago is not indicative of the current acute event. The nurse should focus on the client's current symptoms and their acute presentation to determine the appropriate interventions.