Study objectives: There is a lack of epidemiologic information about duration of QRS complex in the general heart failure population. We sought to describe age, sex, and clinical subset specific prevalence of QRS prolongation in this population.
Methods: Data were abstracted from the Resource Utilization Among Congestive Heart Failure Study, which identified 29,686 patients with heart failure from a large, mixed-model managed-care organization during 1989 to 1999. A target population of 3,471 had echocardiographic data and ECG data obtained from automated sources during the first year of diagnosis. Systolic dysfunction was defined as heart failure plus a left ventricular ejection fraction < 45%.
Measurements and results: Among the heart failure population, 20.8% of the subjects had a QRS duration ≥ 120 ms. A total of 425 men (24.7%) and 296 women (16.9%) had a prolonged QRS duration (p < 0.01). There was a linear relationship between increased QRS duration and decreased ejection fraction (p < 0.01). A prolonged QRS duration of 120 to 149 ms demonstrated increased mortality at 60 months (p = 0.001), when adjusted for age, sex, and race (p = 0.001). Systolic dysfunction was associated with graded increases in mortality across ascending levels of QRS prolongation.
Conclusions: Approximately 20% of a generalized heart failure population can be expected to have a prolonged QRS duration within the first year of diagnosis, suggesting that as many as 20% of patients with heart failure may be candidates for biventricular pacing.