In Reply: We agree with Dr Chen and colleagues that QRS duration is not a fixed parameter, and many conditions affect the measurement by a few milliseconds. However, despite the significant changes in signs, symptoms, hemodynamics, and neurohormonal abnormalities that occur during hospitalization, in our study less than 4% of patients who had a prolonged baseline QRS duration had a normal QRS duration at discharge, and less than 6% who had a normal baseline QRS duration had a prolonged QRS duration at discharge. Our objectives were not to address the dynamic variation of QRS duration over time but to investigate the prognostic value of a QRS duration of 120 milliseconds or longer. The number of patients admitted with electrocardiographic dyssynchrony, the effect on prognosis, and the number who may potentially benefit from a life-saving therapy like cardiac resynchronization therapy—not changes of a few milliseconds in QRS duration—are in our opinion clinically relevant.
QRS Duration in Patients Hospitalized for Worsening Heart Failure—Reply. JAMA. 2008;300(16):1879-1881. doi:10.1001/jama.2008.505