ST-recovery loop of exercise-induced ST deviation in the identification of coronary artery disease: which parameters...

Area of Science:

• Cardiology
• Exercise Physiology
• Diagnostic Imaging

Background:

• Coronary artery disease (CAD) diagnosis often relies on exercise stress tests.
• The ST-heart rate (HR) loop, reflecting cardiac electrical activity during exercise, is a potential diagnostic tool.
• Optimal characterization of the ST-HR loop for discriminating significant coronary artery stenosis requires further investigation.

Purpose of the Study:

• To characterize the ST-heart rate (HR) recovery loop.
• To determine the heart rate (HR) range that best discriminates between patients with and without significant coronary artery stenosis.
• To evaluate the diagnostic performance of normalized area (NA(alpha)) and ST-segment slope changes.

Main Methods:

• Bicycle exercise tests were performed on patients with known coronary artery disease (CAD) and healthy controls.
• ST level and ST-segment slope were continuously monitored.
• The normalized area (NA(alpha)) of the ST-HR loop was calculated for various alpha values (20%-90% HR range), and ST-segment slope changes were analyzed.

Main Results:

• Optimal discrimination was achieved with NA(alpha) at alpha <= 70% in men and alpha <= 30% in women.
• NA(30) outperformed end-exercise ST-depression, ST-HR loop orientation (NA(90)), and ST/HR index in identifying CAD in both sexes.
• Change in ST-segment slope provided significant additional discriminating power in both men and women.

Conclusions:

• The normalized area (NA(alpha)) of the ST-HR loop, particularly NA(30), is a valuable parameter for diagnosing coronary artery disease (CAD).
• A substantial portion of the ST-HR loop, especially in women, should be considered for accurate assessment.
• ST-segment slope changes offer complementary diagnostic information to the ST-HR loop area.