Characterization of repolarization alternans during ischemia: time-course and spatial analysis

Area of Science:

• Cardiology
• Electrophysiology
• Medical Technology

Background:

• T-wave alternans (TWA) is associated with ventricular fibrillation risk, particularly during myocardial ischemia.
• Transient regional ischemia, such as during percutaneous transluminal coronary angioplasty (PTCA), can induce TWA.

Purpose of the Study:

• To develop and apply a methodology for characterizing TWA induced by transient, regional ischemia.
• To investigate the prevalence, magnitude, and spatio-temporal relationship of TWA during PTCA.

Main Methods:

• Analysis of electrocardiogram (ECG) recordings from 95 patients before and during PTCA.
• Utilized a robust method for TWA analysis to characterize episodes by time-course, lead distribution, and waveform.
• Correlated TWA occurrence with occluded coronary arteries, specifically the left anterior descending artery.

Main Results:

• TWA episodes were observed in 33.7% of patients during PTCA.
• Highest TWA prevalence (51.7%) and amplitude were associated with left anterior descending artery occlusion.
• TWA onset occurred within 1-2 minutes of ischemia, with rapid resolution upon reperfusion, demonstrating a regional pattern.

Conclusions:

• TWA is a detectable phenomenon during transient regional ischemia induced by PTCA.
• The characteristics of TWA, including its distribution and waveform, reflect the underlying regional ischemia.
• TWA monitoring may offer insights into ischemia-induced cardiac vulnerability during interventional procedures.