Physiological Adaptation Q 113
Which of the following conditions is most commonly responsible for myocardial infarction?
A. Aneurysm
B. Heart failure
C. Coronary artery thrombosis
D. Renal failure
Correct Answer: C. Coronary artery thrombosis
Coronary artery thrombosis causes occlusion of the artery, leading to myocardial death. Myocardial infarction occurs when a coronary artery is so severely blocked that there is a significant reduction or break in the blood supply, causing damage or death to a portion of the myocardium (heart muscle).
Option A: An aneurysm is an outpouching of a vessel and doesn’t cause an MI. On exertion, elevated blood pressure could cause expansion of the aneurysmal cavity, aggravating the coronary ischemia, and eventually would have produced myocardial infarction. However, this only occurs in very rare cases.
Option D: Renal failure can be associated with MI but isn’t a direct cause. All-cause mortality of dialysis patients with acute myocardial infarction (AMI) is 59% at 1 year and about 73% at 2 years. AMI in patients with nondialysis-dependent advanced CKD is also associated with poor long-term cardiovascular outcomes and survival.
Option B: Heart failure is usually the result of an MI. It produces both a vasculopathy and left ventricular dysfunction and fibrosis. It produces both a vasculopathy and left ventricular dysfunction and fibrosis. Endothelial dysfunction in the coronary arteries can lead to acute coronary events. Left ventricular dysfunction will cause the progression of heart failure, and left ventricular fibrosis and dysfunction provide an arrhythmic substrate.