TQ segment (baseline) alternans during Prinzmetal's variant angina

Area of Science:

• Cardiology
• Electrophysiology

Background:

• Prinzmetal's angina is a condition characterized by vasospastic coronary arteries.
• ST segment alternans is a recognized but uncommon finding in various cardiac conditions.

Purpose of the Study:

• To describe a novel variant of ST segment alternans, termed TQ alternans (TQ Alt), observed in patients with Prinzmetal's angina.
• To investigate the association between TQ Alt and serious ventricular arrhythmias.

Main Methods:

• Observational study of 93 patients diagnosed with Prinzmetal's angina.
• Detailed electrocardiographic (ECG) analysis to identify ST segment alternans and TQ Alt.
• Correlation of ECG findings with the occurrence of ventricular arrhythmias.

Main Results:

• ST segment alternans was observed in 30% (28/93) of patients.
• A new variant, TQ alternans (≥1 mm shift in 2:1 pattern), was identified in 8 of these patients.
• All 8 patients with TQ Alt experienced severe ventricular arrhythmias, including ventricular fibrillation, ventricular tachycardia, and advanced ectopic activity.

Conclusions:

• TQ alternans is a previously undescribed ECG finding associated with Prinzmetal's angina.
• TQ alternans appears to be a marker for significant ventricular arrhythmias in this patient population.
• The findings suggest that ischemia-induced inhomogeneity in myocardial depolarization and repolarization underlies both TQ alternans and associated arrhythmias.