Changes in QRS segments during exercise in relation to scintigraphic myocardial perfusion defects: a multivariate...

Area of Science:

• Cardiology
• Exercise Physiology
• Diagnostic Imaging

Background:

• The relationship between QRS changes during exercise and ischemic heart disease remains debated.
• This study investigates exercise QRS changes in relation to myocardial ischemia, confounding factors, and scintigraphic defects.

Purpose of the Study:

• To determine if exercise-induced QRS changes correlate with myocardial ischemia or necrosis.
• To assess the influence of baseline QRS size, heart rate, and ST magnitude changes during exercise.
• To examine the relationship between QRS alterations and scintigraphic perfusion defects.

Main Methods:

• Advanced computerized vectorcardiography was used in 71 patients undergoing 201TI exercise myocardial scintigraphy.
• Maximal exercise tests were performed, with planar scintigraphic images acquired immediately post-exercise and at 4 hours.
• Scintigraphic images were evaluated blindly.

Main Results:

• Exercise QRS changes correlated with baseline QRS size, heart rate changes, and ST changes.
• Increased QRS magnitudes in specific leads correlated significantly with late perfusion defects.
• These correlations persisted after adjusting for confounding factors.

Conclusions:

• Baseline QRS size, heart rate, and ST magnitude changes can confound exercise QRS response.
• Exercise QRS response remains a significant indicator of late scintigraphic myocardial perfusion defects.
• Increased QRS magnitudes during exercise are associated with myocardial infarctions or long-lasting ischemia.