Anterior QRS loop in hypertrophic cardiomyopathy

Area of Science:

• Cardiology
• Medical Imaging
• Electrophysiology

Background:

• Hypertrophic cardiomyopathy (HCM) is a complex cardiac condition characterized by left ventricular hypertrophy.
• Vectorcardiography (VCG) and electrocardiography (ECG) are diagnostic tools used to assess cardiac electrical activity.

Observation:

• Review of 45 patients with HCM (26 obstructive, 19 nonobstructive) revealed distinct VCG patterns.
• Predominantly anterior QRS loops were observed in 12/19 nonobstructive and 5/26 obstructive HCM patients.
• A large left anterior QRS loop with increased anterior/leftward force was noted, with posterior T loop displacement.

Findings:

• Asymmetric septal and apical hypertrophy correlated with the observed anterior QRS loops.
• Increased electrical forces from hypertrophy are proposed as the cause of the large left anterior loop.
• Some HCM patients exhibited anterior and rightward QRS loops, mimicking myocardial infarction or right ventricular hypertrophy.

Implications:

• HCM should be considered as a potential cause of anterior QRS loops on VCG.
• VCG analysis, specifically identifying large left anterior loops, can aid in diagnosing HCM, especially nonobstructive types.
• HCM diagnosis should be considered in patients presenting with ECG findings suggestive of myocardial infarction or right ventricular hypertrophy.