Utility of Inferior Lead Q-waveforms in diagnosing Ventricular Tachycardia.

Area of Science:

• Cardiology
• Electrophysiology
• Diagnostic Medicine

Background:

• Differentiating wide complex tachycardia (WCT) into ventricular tachycardia (VT) and supraventricular tachycardia with aberration (SVT-A) is clinically challenging.
• Electrocardiogram (ECG) interpretation requires careful analysis of complex waveforms.

Purpose of the Study:

• To evaluate the utility of inferior lead Q-wave patterns (QWC-A, QWC-B) in distinguishing VT from SVT-A in WCT.
• To compare the diagnostic performance of inferior lead criteria against the established Brugada algorithm.

Main Methods:

• 181 WCT cases were analyzed, with ECGs digitally separated into precordial and inferior leads.
• Two electrophysiologists independently applied Brugada and inferior lead algorithms (QWC-A, QWC-B).
• Diagnostic accuracy was compared against final clinical diagnoses.

Main Results:

• VT was diagnosed in 24.9% of cases; SVT-A in 75.1%.
• QWC-A and QWC-B demonstrated high specificity (93.3%, 82.8%) but low sensitivity (33.3%, 35.6%) for VT detection.
• The Brugada algorithm showed higher sensitivity (82.2%) and a superior area under the ROC curve (0.75) compared to inferior lead criteria.

Conclusions:

• Inferior lead Q-wave criteria (QWC-A, QWC-B) offer high specificity but limited sensitivity for diagnosing VT in WCT.
• The Brugada algorithm demonstrated superior diagnostic performance in this cohort.
• Further research integrating these Q-wave criteria with advanced algorithms could enhance VT diagnostic accuracy.