June 10, 2008 Among patients hospitalized with heart failure, having a longer than normal QRS duration (a measurement of the electrical conducting time of the heart on an electrocardiogram (ECG)] appears to predict a high risk of death or rehospitalization within a few months after discharge, according to a new study.
An ECG is routinely obtained on all patients admitted with heart failure. Hospitalization for heart failure is a major public health problem in the developed world, with the United States and Europe each reporting more than 1 million heart failure hospitalizations per year. The frequency and the predictive value of a prolonged QRS duration during an admission for heart failure has not been well studied. Establishing the prognostic value of a prolonged QRS duration during hospitalization for heart failure may aid in tailoring therapy to improve postdischarge morbidity and mortality, according to background information.
Mihai Gheorghiade, M.D., and Norman C. Wang, M.D., of the Northwestern University Feinberg School of Medicine, Chicago, and investigators with the Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study With Tolvaptan (EVEREST) trial, investigated the relationship of QRS duration and changes during the course of hospitalization to outcomes such as death and hospitalization for heart failure.
The study included 4,133 patients hospitalized for heart failure and having a left ventricular ejection fraction (LVEF; a measure of how well the left ventricle of the heart pumps with each contraction) of 40 percent or less. After excluding 1,029 patients with a pacemaker, implantable cardioverter-defibrillator, or both at enrollment and 142 patients without a reported baseline QRS duration, 2,962 patients were included in this analysis: 1,641 had a normal QRS duration (less than 120 ms) and 1,321 had a prolonged QRS duration (120 ms or greater). Median (midpoint) follow-up time was 9.9 months.
There were 678 total deaths (307 of 1,641 patients [18.7 percent] with a normal baseline QRS duration and 371 of 1,321 [28.1 percent] with a prolonged baseline QRS duration). The most common cause of death was heart failure followed by sudden cardiac death. The composite of cardiovascular death or hospitalization for heart failure was more frequent in patients with a prolonged baseline QRS duration at 3 months after enrollment (21.1 percent vs. 14.6 percent) and at the end of the follow-up period of 9.9 months (41.6 percent vs. 32.4 percent). After adjusting for multiple variables, compared with normal baseline QRS duration, prolonged QRS duration was associated with a 24 percent increased risk of death and a 28 percent increased risk for the composite of cardiovascular death or hospitalization for heart failure.
"In this analysis, a prolonged QRS duration was present in 45 percent of patients admitted with heart failure and reduced LVEF, did not appear to significantly change during hospitalization, and was independently associated with high postdischarge mortality and readmission rate. This high morbidity and mortality was observed even though patients were well-treated with standard medical therapy that included beta-blockers and angiotensin-converting enzyme [ACE] inhibitors or angiotensin II receptor blockers [ARBs]," the authors write.
"Measurement of the QRS duration on an ECG has significant advantages as a tool in the clinical setting. It is relatively inexpensive, simple to perform, and yields an instant result. The measurement is objective and does not require specialized training to interpret. In addition, the QRS duration is stable in the majority of patients during the course of their hospitalization. Perhaps most important, a prolonged QRS duration becomes a potential target for intervention [with existing therapy], which may improve postdischarge mortality and morbidity."
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- Norman C. Wang; Aldo P. Maggioni; Marvin A. Konstam; Faiez Zannad; Holly B. Krasa; John C. Burnett, Jr; Liliana Grinfeld; Karl Swedberg; James E. Udelson; Thomas Cook; Brian Traver; Christopher Zimmer; Cesare Orlandi; Mihai Gheorghiade for the Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study With Tolvaptan (EVEREST) Investigators. Clinical Implications of QRS Duration in Patients Hospitalized With Worsening Heart Failure and Reduced Left Ventricular Ejection Fraction. JAMA, 2008;299(22):2656-2666 [link]
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