**Core Concept**
In a patient with a history of myocardial infarction (MI), presenting with chest pain on exertion, the primary concern is to assess for potential cardiac ischemia or revascularization. This scenario necessitates a thorough evaluation of the patient's cardiac function and potential for coronary artery disease progression.

**Why the Correct Answer is Right**
Performing stress tests is the next best step in this clinical scenario because it allows for the evaluation of cardiac function under physical stress, which is a more accurate indicator of ischemia than resting electrocardiogram (ECG) or biomarkers. Stress tests, such as exercise treadmill testing (ETT) or pharmacological stress testing, assess the heart's ability to respond to physical demand, providing valuable information on coronary artery disease and potential areas of myocardial ischemia. This step is crucial in determining the need for further diagnostic testing, such as coronary angiography, or revascularization procedures like percutaneous coronary intervention (PCI).

**Why Each Wrong Option is Incorrect**
**Option B:** Performing cardiac biomarkers may be useful in the acute setting of MI but is not the next best step in this scenario, as the patient's vitals are stable and chest is clear, indicating a low likelihood of acute MI. Additionally, biomarkers may not accurately detect ischemia in patients with chronic MI or those who are not experiencing acute MI symptoms.

**Option C:** Performing PCI is not the next best step without first establishing the presence and extent of coronary artery disease through stress testing or coronary angiography. PCI is a revascularization procedure that requires careful patient selection and planning.

**Option D:** Performing transvenous pacing is not indicated in this scenario, as there is no evidence of heart block or other indications for pacing. Transvenous pacing is typically used in patients with symptomatic bradycardia or heart block.

**Clinical Pearl / High-Yield Fact**
In patients with a history of MI, it's essential to perform stress tests before proceeding with revascularization procedures like PCI. This approach helps identify patients who may benefit from revascularization and reduces the risk of unnecessary procedures.

**✓ Correct Answer: A. Perform Stress tests**