The most common cause of myocardial infarction is?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2019

Medical & Surgical Nursing

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2019

Explanation

The most frequent cause of Myocardial Infarction (MI) is the formation of a thrombus (blood clot) within a coronary artery.
This process accounts for over 90% of MI cases and is initiated by the rupture of a pre-existing atherosclerotic plaque.
When the plaque ruptures, it exposes highly thrombogenic material, which activates the coagulation cascade, leading to the formation of an occlusive clot that stops blood flow to the heart muscle.

Option A: Aneurysm of a coronary artery is an abnormal dilation of the vessel wall. While it can be a site for thrombus formation, it is a very rare primary cause of MI.
Option B: An embolus is a blood clot or piece of debris that travels from another part of the body and lodges in a coronary artery. This is a much less frequent cause of MI compared to a thrombus forming in-situ on a plaque.
Option D: Coronary artery vasospasm is a sudden, severe constriction of the artery. It can cause MI but is an uncommon cause, often associated with specific conditions like Prinzmetal's angina or illicit drug use (e.g., cocaine).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of Myocardial Infarction as background academic context rather than a clinical decision trigger.
Rapid identification of MI is critical. Nurses must be able to recognize symptoms (chest pain, shortness of breath, diaphoresis) and initiate protocols, including obtaining a 12-lead ECG within 10 minutes of patient arrival.
The cornerstone of early MI management is antiplatelet (e.g., Aspirin) and antithrombotic (e.g., Heparin) therapy to target the underlying thrombus, alongside reperfusion strategies like PCI or fibrinolytics.
Patient education post-MI is a key nursing role, focusing on lifestyle modifications (diet, exercise, smoking cessation) and medication adherence to manage the underlying atherosclerosis and prevent recurrence.

How to Approach the Question

First, identify the keywords in the question stem: 'most common cause' and 'myocardial infarction'.
This is a factual recall question that tests your knowledge of the pathophysiology of ischemic heart disease.
Recall that myocardial infarction is the death of heart muscle tissue due to a lack of blood supply.
Consider the primary underlying disease process for MI, which is atherosclerosis.
Evaluate the given options in terms of their frequency as a cause of MI. A thrombus is a clot that forms in place, an embolus travels, a vasospasm is a constriction, and an aneurysm is a vessel wall weakness.
Conclude that the acute event precipitating most MIs is the formation of a thrombus on a ruptured atherosclerotic plaque, making it the 'most common' cause.

Concept Tested & Keywords

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