Understanding Coronary Artery Disease: Diagnosis and Management

Stress Testing evaluates how the heart responds to increased oxygen demand. This can be achieved via physical activity on a treadmill or through medication-induced simulation of exercise.

Invasive Testing and Intervention

When non-invasive tests suggest significant disease, Cardiac Catheterization is performed. During this procedure, a catheter is inserted (usually via the femoral or radial artery) and IV contrast dye is injected under fluoroscopy to create a coronary angiogram. This allows the physician to visualize the exact location and severity of blockages.

If a blockage is identified—typically those greater than 70%—Percutaneous Coronary Intervention (PCI) may be indicated. This often involves:

1. Balloon Angioplasty: A balloon is inflated at the site of the blockage to compress the plaque against the arterial wall and dilate the vessel.
2. Stent Placement: An expandable mesh structure is placed to maintain vessel patency and prevent the artery from collapsing.

Pharmacological Management

Pharmacological therapy for CAD aims to reduce myocardial oxygen demand, prevent clot formation, and manage risk factors like hypertension and hyperlipidemia.

Reducing Oxygen Demand and Vasodilation

Nitrates (e.g., Nitroglycerin, Isosorbide) are used to reduce the frequency of anginal attacks through vasodilation.

• Side Effects: Common side effects include headaches (due to cerebral vasodilation) and orthostatic hypotension.
• Tolerance: To prevent nitrate tolerance, patients using topical applications (like nitro paste) must have a 10–14 hour nitrate-free interval.

Beta Blockers (e.g., Metoprolol, Carvedilol) are a cornerstone of therapy for patients with chronic stable angina or a history of MI. They decrease heart rate, contractility, and systemic vascular resistance (SVR), thereby reducing myocardial oxygen demand.

• Contraindications: They are contraindicated in patients with severe bradycardia or acute heart failure and should be avoided in patients with asthma due to the risk of bronchospasm.
• Warning: Never stop beta blockers abruptly, as this can cause a sudden increase in the intensity of anginal attacks.

Calcium Channel Blockers serve as an alternative if beta blockers are poorly tolerated or contraindicated, promoting both systemic and coronary vasodilation.

Preventing Remodeling and Managing Comorbidities

ACE Inhibitors (e.g., Lisinopril) are indicated for patients with diabetes, hypertension, or a low ejection fraction ($\leq 40\%$). They are vital for preventing or reversing ventricular remodeling following an MI. If a patient develops a persistent cough or angioedema (common side effects), they may be switched to Angiotensin II Receptor Blockers (ARBs).

Antiplatelet Therapy

Following procedures like stent placement, antiplatelet therapy (such as Aspirin or Clopidogrel) is essential to prevent thrombus formation on the new device.

Clinical Note: When monitoring patients post-cardiac catheterization, always check distal pulses (e.g., pedal pulses if the femoral artery was used) to ensure adequate perfusion to the extremity.