Left-axis deviation: etiologic factors in one-hundred patients.

Area of Science:

• Cardiology
• Electrophysiology

Background:

• Left anterior fascicular block (LAD) is a conduction abnormality.
• Its incidence and causes require further elucidation, particularly in relation to age and cardiac conditions.

Purpose of the Study:

• To analyze the clinical and electrocardiographic findings in patients with LAD.
• To identify the underlying mechanisms and causes of LAD in a consecutive case series.

Main Methods:

• Retrospective analysis of 100 consecutive cases diagnosed with LAD.
• Evaluation of clinical diagnoses, electrocardiographic patterns, and patient history.
• Correlation of LAD with conditions such as arteriosclerotic heart disease, myocardial infarction, and left ventricular hypertrophy.

Main Results:

• LAD incidence increases with age, being uncommon below forty.
• Left bundle branch block (LAHB) was the most frequent mechanism (40%), often associated with myocardial infarction or degenerative processes.
• Inferior myocardial infarction accounted for approximately one-sixth of LAD cases.
• Left ventricular hypertrophy was an uncommon cause of LAD.

Conclusions:

• LAHB is a significant mechanism contributing to LAD, with varied etiologies including infarction and primary conduction system disease.
• Age is a factor in LAD prevalence.
• Further investigation may be needed for unexplained LAD cases, potentially involving anterior wall hypertrophy.