A patient with acute coronary syndrome presents a typical scenario for underlying coronary artery disease. Which statement best reflects the underlying cause in this context?

• A. Arrhythmia is the primary cause.
• B. Valvular disease is the primary cause.
• C. Coronary heart disease is the underlying cause.
• D. Myocarditis is the underlying cause.

Answer: (C)

When acute coronary syndrome occurs, the initiating problem is the presence of atherosclerotic plaques in the coronary arteries that can rupture or erode. This exposes thrombogenic material, provoking rapid platelet aggregation and thrombus formation, which can partially or completely occlude a coronary vessel and severely reduce blood flow to a portion of the heart. That sequence—coronary artery disease leading to plaque disruption and thrombosis—is what drives the ischemia or infarction seen in ACS, making coronary heart disease the underlying cause here. Arrhythmias may arise as a complication of myocardial ischemia, but they don't initiate the event. Valvular disease or myocarditis are separate conditions and do not explain the typical plaque-rupture/thrombus mechanism of ACS.