QRS prolongation measured by a new computerized method: a sensitive marker for detecting exercise-induced ischemia

Area of Science:

• Cardiology
• Diagnostic Imaging
• Exercise Physiology

Background:

• Exercise electrocardiography (ECG) is a common tool for diagnosing coronary artery disease (CAD).
• ST-T segment changes during exercise ECG can be difficult to interpret, especially in patients with non-diagnostic results.
• Thallium stress testing is an established method for CAD detection.

Purpose of the Study:

• To evaluate the diagnostic utility of exercise-induced changes in QRS duration.
• To compare the accuracy of QRS duration changes with thallium stress testing for CAD detection.

Main Methods:

• A computerized 'optic scanner' was used to measure QRS duration changes during exercise ECG.
• Three groups were studied: patients with positive exercise ECG (Group 1), patients with non-diagnostic exercise ECG (Group 2), and healthy controls (Group 3).
• Results were compared with thallium stress testing findings.

Main Results:

• Group 1 showed a mean QRS width increase of 12.4 ms, while Group 3 showed a mean decrease of 4.9 ms (p < 0.0001).
• Group 2 exhibited a mean QRS prolongation of 7.8 ms, significantly different from controls (p < 0.0001) but not Group 1.
• Exercise QRS prolongation demonstrated 93% sensitivity, 71% specificity, and 86% positive predictive value compared to thallium stress testing.

Conclusions:

• Exercise-induced QRS duration prolongation is a valuable indicator in diagnosing coronary artery disease.
• Measuring QRS duration changes enhances the diagnostic accuracy of the exercise ECG stress test.
• This quantitative approach offers a promising adjunct to traditional stress testing methods.