Cross-sectional relations of electrocardiographic QRS duration to left ventricular dimensions

OBJECTIVES: The goal of this study was to assess the relations of electrocardiographic QRS duration to left ventricular (LV) measurements in individuals without heart failure (HF) or prior myocardial infarction (MI). BACKGROUND: Increased electrocardiographic QRS duration (>/=120 ms) is a marker of ventricular dyssynchrony. METHODS: We evaluated the relations of maximal electrocardiographic QRS duration to echocardiographic LV dimensions in 4,534 Framingham Heart study participants (mean age 54 years, 57% women) without prior HF or MI. QRS duration was analyzed as a continuous variable and as categories (<100, 100 to 119, and >/=120 ms). RESULTS: In linear regression models, LV mass, end-diastolic dimension, and septal and posterior wall thicknesses were positively related to log-QRS duration, whereas fractional shortening (FS) was inversely related (p < 0.001). There was a significant trend for increasing LV mass and dimensions, and decreasing FS across categories of QRS duration (p < 0.001). Left bundle branch block was associated with higher LV mass and lower FS compared with a normal QRS duration (p < 0.001). CONCLUSIONS: In our community-based sample of individuals free of HF and MI, increasing electrocardiographic QRS duration was positively related to LV mass and dimensions, and inversely associated with LV FS. Additional investigations are warranted to elucidate the mechanisms underlying the observed associations.