Rethinking False Positive Exercise Electrocardiographic Stress Tests by Assessing Coronary Microvascular Function.

Area of Science:

• Cardiology
• Diagnostic Testing
• Vascular Medicine

Background:

• Exercise electrocardiographic stress testing (EST) traditionally relies on obstructive coronary artery disease (CAD) for validation.
• Myocardial ischemia can stem from coronary microvascular dysfunction (CMD) even without obstructive CAD.

Purpose of the Study:

• To evaluate the specificity of EST in identifying an ischemic substrate in patients with angina and nonobstructive coronary arteries (ANOCA).
• To compare EST findings against a reference standard of coronary microvascular function.

Main Methods:

• Patients with ANOCA underwent invasive coronary physiological assessment (adenosine, acetylcholine) to define CMD.
• EST was conducted using the standard Bruce treadmill protocol, with ischemia defined by ST-segment depression.
• The study was powered to achieve ≥91% specificity.

Main Results:

• Ischemia during EST was 100% specific for CMD in the study population (n=102).
• Acetylcholine flow reserve emerged as the strongest predictor of exercise-induced ischemia.
• The false positive rate of EST was 0% when compared to microvascular dysfunction.

Conclusions:

• In ANOCA patients, ischemia detected by EST is highly specific for an underlying ischemic substrate.
• These results question the established notion of a high false positive rate for EST in this patient group.