Sex and race differences in QRS duration

Area of Science:

• Cardiology
• Physiology

Background:

• Electrocardiogram (ECG) parameters like QRS duration are crucial for cardiac health assessment.
• Understanding variations in QRS duration across different demographic groups is essential for accurate interpretation.

Purpose of the Study:

• To investigate sex and race differences in QRS durations.
• To analyze the dependency of QRS durations on heart rates and other physiological factors.

Main Methods:

• Analysis of 420,615 ECGs from 523 healthy individuals (111 African females, 130 Caucasian females, 125 African males, 129 Caucasian males).
• Comparison of QRS/RR slopes and QRS durations at specific RR intervals (1s and 0.5s) between sex- and race-defined subgroups.
• Inclusion of lean body mass as a covariate in the analysis.

Main Results:

• QRS duration exhibits heart rate dependency, with increases in ~35% of subjects and decreases in others.
• Significant differences in QRS durations were observed between all sex and race subgroups at both RR intervals (P < 0.001).
• After accounting for lean body mass, the race-based difference in QRS duration was comparable to the sex-based difference.

Conclusions:

• QRS durations are influenced by heart rate and show significant variations between males and females, as well as between individuals of African and Caucasian origin.
• Potential disparities in the efficacy of cardiac resynchronization therapy may exist between patients of African and Caucasian descent, particularly when stratified by QRS duration.