Ischemic Heart Disease vs. Coronary Artery Disease: Understanding the Difference

Coronary Artery Disease (CAD) is the most common cause of Ischemic Heart Disease (IHD), but they are not synonymous.

Ischemic Heart Disease (IHD)

Clinical syndrome of myocardial oxygen supply-demand mismatch. Causes include:

• CAD (atherosclerotic stenosis) – ~90% of cases.
• Coronary vasospasm (Prinzmetal's angina).
• Microvascular dysfunction (CMD/INOCA).
• Severe anemia, hypertension, valvular disease, tachycardia.
• Cocaine/amphetamine use.

Coronary Artery Disease (CAD)

Specific pathology: atherosclerotic plaque narrowing coronary arteries. Can be:

• Obstructive (≥50% stenosis).
• Non-obstructive (<50% but vulnerable plaque).

Clinical Overlap

CAD → IHD when ischemia occurs. But IHD can exist without CAD (e.g., microvascular angina), and CAD can be asymptomatic (silent ischemia). Diagnosis combines symptoms, stress testing, CT angiography, invasive angiography, and functional assessment (FFR, CFR).