Increase in S-wave amplitude during ischemic ST-segment depression in stable angina pectoris

Area of Science:

• Cardiology
• Electrophysiology
• Ischemic Heart Disease

Background:

• Chronic stable angina is characterized by myocardial ischemia.
• Electrocardiogram (ECG) changes, particularly ST-segment depression, are used to diagnose ischemia.
• The S-wave amplitude's role in detecting ischemia requires further investigation.

Purpose of the Study:

• To investigate the behavior of S-wave amplitude during ischemic episodes.
• To determine if S-wave amplitude changes can serve as a marker for subendocardial ischemia.
• To assess the sensitivity and specificity of S-wave amplitude changes compared to ST-segment depression.

Main Methods:

• Exercise testing and ambulatory electrocardiographic (Holter) monitoring were performed in patients with chronic stable angina and healthy volunteers.
• S-wave and R-wave amplitudes were analyzed during induced and spontaneous ischemic events.
• Dipyridamole echocardiography was used to assess regional wall motion abnormalities.

Main Results:

• Exercise-induced ST-segment depression was associated with increased S-wave amplitude in 49 of 50 patients.
• Holter monitoring showed increased S-wave amplitude in 169 of 170 ischemic episodes.
• Increased S-wave amplitude occurred even without ST-segment changes and correlated with wall motion abnormalities.

Conclusions:

• An increased S-wave amplitude is almost invariably associated with subendocardial ischemia.
• This finding can be a sensitive, though less specific, additional marker of myocardial ischemia.
• S-wave amplitude changes may detect ischemia even in the absence of diagnostic ST-segment depression.