Exercise-induced QRS axis shift and its clinical significance

Area of Science:

• Cardiology
• Diagnostic Medicine

Background:

• Exercise electrocardiography is a common diagnostic tool.
• QRS axis shifts can occur during exercise tests.
• The diagnostic significance of exercise-induced QRS axis shifts requires further investigation.

Purpose of the Study:

• To determine the incidence of QRS axis shifts during exercise tests.
• To investigate the relationship between QRS axis shifts and ischemic heart disease.

Main Methods:

• Analysis of 1810 Master's two-step test electrocardiograms.
• Quantification of QRS axis shifts in degrees (right and left).
• Comparison of QRS axis shift prevalence with positive Master's tests and diagnosed ischemic heart disease.

Main Results:

• QRS axis shifts of 30 degrees or more (right or left) were observed in a minority of patients (2.1% and 0.7%, respectively).
• A significant association was found between QRS axis shifts of 30 degrees or more (right or left) and higher frequencies of positive Master's tests and ischemic heart disease.
• Patients with smaller axis shifts (<15 degrees) showed lower rates of positive tests and disease.

Conclusions:

• Exercise-induced QRS axis shifts, particularly larger deviations, are associated with ischemic heart disease.
• The QRS axis shift during exercise testing can serve as a valuable indicator for diagnosing ischemic heart disease.