**Core Concept**
Aortic stenosis is a valvular heart disease characterized by narrowing of the aortic valve opening, leading to increased resistance to left ventricular outflow. Exercise stress testing, as per the Bruce Protocol, is a diagnostic tool to assess the functional significance of aortic stenosis and estimate the risk of cardiac events.

**Why the Correct Answer is Right**
The observed regional pressure gradient of 60 mm Hg between the two sides of the aortic valve during exercise stress testing suggests severe aortic stenosis, which poses a significant risk of cardiac complications, including syncope, heart failure, and sudden death. The development of fatigue and dyspnea at 11 minutes, despite a normal heart rate and blood pressure, indicates a compromised cardiac output due to the fixed obstruction caused by the stenotic valve. This warrants an urgent evaluation for aortic valve replacement.

**Why Each Wrong Option is Incorrect**
**Option A:** Medical management with beta-blockers and diuretics may help alleviate symptoms but is not the best management for severe aortic stenosis, as it does not address the underlying cause of the obstruction.

**Option B:** Coronary angiography is not indicated in this scenario, as the primary concern is the aortic stenosis rather than coronary artery disease.

**Option C:** Cardiac catheterization with aortic valve replacement is the preferred treatment for severe aortic stenosis but is not the immediate next step without further evaluation and optimization of the patient's condition.

**Option D:** Transcatheter aortic valve replacement (TAVR) is a viable option for patients who are high-risk surgical candidates, but it is not the best initial management strategy for this asymptomatic patient with severe aortic stenosis.

**Clinical Pearl / High-Yield Fact**
In patients with severe aortic stenosis, the development of symptoms during exercise stress testing is a critical predictor of cardiac events and warrants prompt evaluation for aortic valve replacement.

**Correct Answer: C. Cardiac catheterization with aortic valve replacement is the preferred treatment for severe aortic stenosis.**