Anatomic distribution of myocardial ischemia as a determinant of exercise-induced ST-segment depression

Area of Science:

• Cardiology
• Nuclear Cardiology
• Diagnostic Imaging

Background:

• ST depression on electrocardiography (ECG) is a common indicator of myocardial ischemia.
• Single-photon emission computed tomography (SPECT) is used to assess myocardial perfusion and quantify ischemia.
• The relationship between ECG findings and SPECT data is crucial for diagnosing coronary artery disease (CAD).

Purpose of the Study:

• To investigate the correlation between ST depression and SPECT-derived perfusion defects.
• To determine if the anatomical distribution of ischemia affects this correlation.
• To evaluate the impact of ischemia distribution on the accuracy of assessing CAD using ST depression.

Main Methods:

• Retrospective analysis of 129 patients with inducible ST depression (>0.1 mV) and reversible perfusion defects on SPECT.
• Patients categorized into groups with anatomically contiguous (n=68) or opposed (n=61) ischemic regions.
• Correlation and multivariate regression analyses performed to assess relationships between ST depression magnitude, defect size, and severity.

Main Results:

• In the contiguous ischemia group, ST depression correlated significantly with defect size (r=0.40) and severity (r=0.38).
• In the opposed ischemia group, ST depression did not significantly correlate with defect extent or severity.
• ST depression was paradoxically greater in the contiguous ischemia group compared to the opposed group, even after adjusting for perfusion indexes (p<0.001).

Conclusions:

• The anatomical distribution of myocardial ischemia significantly alters the relationship between ST depression and functional indicators of ischemia.
• Relying solely on ST depression magnitude may lead to inaccurate assessments of coronary artery disease.
• Considering the spatial pattern of ischemia is essential for improving the diagnostic accuracy of ECG in patients with suspected CAD.