Subendocardial ischemia: Does CMD really exist?

Area of Science:

• Cardiology
• Physiology
• Diagnostic Imaging

Background:

• Patients with angina and non-obstructive coronary artery disease need specific diagnoses for effective treatment.
• The broad application of coronary microvascular dysfunction (CMD) as a diagnosis warrants closer examination.

Purpose of the Study:

• To systematically categorize coronary pathophysiology in patients with angina but without obstructive epicardial coronary disease.
• To differentiate between various mechanisms underlying myocardial ischemia in this patient group.

Main Methods:

• Analysis of a large clinical database and case examples.
• Systematic exploration to distinguish four categories of coronary pathophysiology.
• Utilizing dipyridamole vasodilator stress and assessing coronary flow and subendocardial uptake.

Main Results:

• Identified four distinct categories of coronary pathophysiology.
• The largest group exhibits subendocardial ischemia with intact flow despite diffuse epicardial disease.
• Recognized a new group with ST-segment changes but normal coronary flow, possibly due to hyperemia-induced stretch.

Conclusions:

• Subendothelial ischemia is a dominant factor in most "no stenosis angina" patients, making its mechanism crucial for treatment.
• Accurate diagnosis requires excluding confounding factors like caffeine and precise quantification of coronary blood flow.
• Understanding these pathophysiologic categories enables more targeted and beneficial treatments for angina patients.