1.Ventricular dyssynchrony is common among heart failure patients with narrow QRS complex
Yaakob ZH ; Syed Tamin S ; Nik Zainal NH ; Chee KH ; Chong WP ; Hashim NE ; Singh R ; Zainal Abidin I ; Haron H ; Wan Ahmad WA
Journal of University of Malaya Medical Centre 2009;12(2):57-62
Current selection guideline for CRT uses broad QRS duration (>120 ms) as a marker for ventricular
dyssynchrony. However, more recent data supports mechanical marker specifically measured
by Tissue Doppler Imaging (TDI) as a better criterion to predict response to CRT. Sixty seven
patients with significant left ventricular dysfunction (EF less than 40%) and narrow QRS complex
were prospectively enrolled. They underwent Tissue Doppler Imaging (TDI) study to evaluate
intraventricular mechanical dyssynchrony. Dyssynchrony index which is defined as standard
deviation of time to peak systolic velocity in twelve ventricular segments was measured. A value
greater than 32.6 is taken to reflect significant ventricular dyssynchrony. Overall 38 patients
(56.7%) demonstrated significant dyssynchrony. There was no significant correlation between QRS
duration and the Ts-SD-12 (r = 0.14, p = 0.11). Ventricular mechanical dyssynchrony is common
in patients with normal QRS duration. Therefore, QRS duration alone will miss a substantial
proportion of suitable patients for CRT and therefore deny them this adjunct therapy. We propose
echocardiographic parameters, specifically TDI, to be included in patient selection criteria for CRT.
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