ST-segment level and slope in exercise-induced myocardial ischemia evaluated with body surface potential mapping

Area of Science:

• Cardiology
• Medical Imaging
• Diagnostic Electrocardiography

Background:

• 12-lead electrocardiography has limitations in detecting acute and old myocardial infarctions (MIs).
• Body surface potential mapping (BSPM) offers superior detection capabilities for myocardial infarctions.
• Understanding electrocardiographic criteria for acute reversible myocardial ischemia is crucial for timely diagnosis and treatment.

Purpose of the Study:

• To utilize BSPM to examine electrocardiographic criteria for acute reversible myocardial ischemia.
• To identify optimal locations and criteria for detecting ST depression and ST-slope decrease using BSPM.
• To compare the diagnostic performance of ST depression versus ST slope for identifying ischemia in patients with coronary artery disease (CAD).

Main Methods:

• 123-channel BSPM was performed in 45 patients with documented CAD and 25 healthy controls during exercise testing.
• Ischemia location was confirmed by coronary angiography and thallium scintigraphy.
• ST amplitude and ST slope were measured at specific time points and locations relative to the J-point.

Main Results:

• Optimal locations for detecting ST depression (5 cm below V5) and ST-slope decrease (left side) were identified.
• ST depression detected CAD patients from controls with 84% sensitivity and 96% specificity (cut-off -10 microV).
• ST slope detected CAD patients from controls with 93% sensitivity and 88% specificity (cut-off 320 microV/s), with a trend towards higher diagnostic accuracy (97% vs 93% AUC).

Conclusions:

• BSPM can identify specific regions sensitive to ST depression and ST-slope decrease, irrespective of ischemia location or MI history.
• ST slope is a sensitive and specific marker for transient myocardial ischemia.
• ST slope analysis may offer superior diagnostic performance compared to ST depression for detecting myocardial ischemia.