The first choice of drug for treating MI?

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Explanation

Streptokinase is a thrombolytic (fibrinolytic) agent, meaning it dissolves blood clots.
In ST-segment elevation MI (STEMI), the primary cause is a thrombus occluding a coronary artery.
By dissolving the clot, Streptokinase restores blood flow (reperfusion) to the ischemic heart muscle, limiting infarct size and improving outcomes.
It is considered a definitive treatment for the underlying cause of the MI, especially when immediate percutaneous coronary intervention (PCI) is not available.

Option A: Streptomycin is an aminoglycoside antibiotic used to treat bacterial infections, most notably tuberculosis.
Option C: Nitroglycerin is a vasodilator used for symptomatic relief of chest pain (angina). It reduces the heart's workload by decreasing preload and afterload but does not dissolve the underlying clot causing the infarction.
Option D: Heparin is an anticoagulant. Its function is to prevent the formation of new clots and the extension of existing ones. It does not have the ability to break down a clot that has already formed.

Clinical Relevance

Nursing practice connection: Knowing Pharmacological management of acute Myocardial Infarction (MI) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
The concept of 'door-to-needle' time is critical in MI management. For thrombolytic therapy to be effective, it must be administered as soon as possible after symptom onset, ideally within 30 minutes of hospital arrival.
Nurses play a vital role in screening for contraindications to thrombolysis, such as recent major surgery, head trauma, or history of bleeding disorders, to prevent life-threatening complications like intracranial hemorrhage.
Monitoring for reperfusion is key. Nurses should watch for signs like resolution of ST-segment elevation, relief of chest pain, and the appearance of reperfusion arrhythmias on the ECG.

How to Approach the Question

First, identify the core of the question: it asks for the 'first choice' drug for 'treating' MI.
Analyze the term 'treating'. This can mean either relieving symptoms or resolving the underlying cause. In the context of MI, resolving the cause (the clot) is the definitive treatment.
Evaluate each option based on its mechanism of action in MI: Streptomycin (antibiotic), Streptokinase (clot-buster), Nitroglycerin (vasodilator for pain), Heparin (prevents new clots).
Recognize that Streptokinase is the only drug listed that directly addresses the coronary artery occlusion by dissolving the thrombus.
Differentiate this definitive action from the symptomatic relief provided by Nitroglycerin and the preventative action of Heparin.
Conclude that Streptokinase is the most appropriate answer representing the class of drugs that provides definitive treatment for the MI itself.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 2 pp. 25-27, 22-24

E6 Medicine Davidson Principles Practice 24e p. 520-522

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