Key result
QRS duration was not related to left ventricular dyssynchrony, which was present in 70% of wide, 60% of intermediate, and 27% of narrow QRS patients with severe heart failure.
Why the study?
Does QRS duration accurately predict the presence of left ventricular dyssynchrony in patients with severe heart failure?
Observational (n=90)
Does QRS duration accurately predict the presence of left ventricular dyssynchrony in patients with severe heart failure?
A significant proportion of heart failure patients with wide QRS lack mechanical dyssynchrony, while over a quarter with narrow QRS exhibit it, suggesting QRS duration alone is an imperfect marker for CRT patient selection.
QRS duration imperfectly predicts LV dyssynchrony in severe HF; leaves open whether mechanical assessment refines CRT selection.
INTRODUCTION: Patients with end-stage heart failure and a wide QRS complex are considered candidates for cardiac resynchronization therapy (CRT). However, 20% to 30% of patients do not respond to CRT. Lack of left ventricular dyssynchrony may explain the nonresponse. Accordingly, we evaluated the presence of left ventricular dyssynchrony using tissue Doppler imaging (TDI) in 90 consecutive patients with heart failure. METHODS AND RESULTS: Ninety patients with severe heart failure (left ventricular ejection fraction <35%, New York Heart Association class III-IV) were prospectively evaluated. Based on QRS duration, 30 consecutive patients with a narrow QRS complex were included (QRS duration <or=120 ms), 30 patients with an intermediate QRS duration (120-150 ms), and 30 patients with a wide QRS complex (>150 ms). All patients underwent TDI to assess left ventricular dyssynchrony. Extensive left ventricular dyssynchrony was defined as an electromechanical delay on TDI between the septum and lateral wall, the so-called septal-to-lateral delay, of >60 ms. Severe dyssynchrony was observed in 27% of patients with narrow QRS complex, 60% with intermediate QRS duration, and 70% with wide QRS complex. No relation existed between QRS duration and septal-to-lateral delay. CONCLUSION: From 30% to 40% of heart failure patients with QRS duration >120 ms do not exhibit left ventricular dyssynchrony, which may explain the nonresponse to CRT. Alternatively, 27% of patients with heart failure and a narrow QRS complex show significant left ventricular dyssynchrony and may be candidates for CRT.
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Bleeker et al. (2004) conducted an observational in Severe heart failure (n=90). Wide QRS complex (>150 ms) vs. Narrow QRS complex (<=120 ms) and intermediate QRS (120-150 ms) was evaluated on Extensive left ventricular dyssynchrony (septal-to-lateral delay >60 ms). QRS duration was not related to left ventricular dyssynchrony, which was present in 70% of wide, 60% of intermediate, and 27% of narrow QRS patients with severe heart failure.
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