**Core Concept**
Aortic stenosis is a valvular disease characterized by narrowing of the aortic valve, leading to impaired left ventricular ejection and increased left ventricular pressure. This results in reduced cardiac output, myocardial ischemia, and progressive ventricular dysfunction—key features in patients with angina, syncope, and congestive heart failure.

**Why the Correct Answer is Right**
Aortic stenosis causes obstruction to blood flow from the left ventricle to the aorta, leading to increased left ventricular pressure and hypertrophy. This results in decreased coronary perfusion, causing angina. The reduced cardiac output leads to poor perfusion of vital organs, triggering syncope. Chronic pressure overload eventually causes left ventricular failure, manifesting as congestive heart failure. These symptoms form a classic triad in aortic stenosis, especially in older adults.

**Why Each Wrong Option is Incorrect**
Option A: Atrioventricular (AV) valve stenosis (e.g., mitral stenosis) does not typically cause angina, syncope, or heart failure in the same triad. It may present with dyspnea and pulmonary congestion but not the classic triad described.
Option B: Tricuspid regurgitation is a right-sided valvular issue, affecting right ventricular function. It does not cause left ventricular ischemia or reduced systemic perfusion, so it does not explain angina or syncope.
Option D: Aortic regurgitation causes volume overload, leading to left ventricular dilation and failure, but it typically presents with symptoms of volume overload (e.g., dyspnea, fatigue), not the ischemic triad of angina and syncope.

**Clinical Pearl / High-Yield Fact**
In elderly patients, the triad of angina, syncope, and heart failure is highly suggestive of aortic stenosis—especially when the patient has a history of hypertension or aortic valve calcification. Early diagnosis is critical, as surgical intervention can significantly improve survival.

✓ Correct Answer: C. Aortic stenosis