Abstract 2817: Degree of Left Ventricular Dyssynchrony in Heart Failure Patients Is Related to QRS Width

Background Recent narrow QRS cardiac resynchronization therapy (CRT) trials using tissue Doppler imaging (TDI) dyssynchrony criteria have not successfully predicted response. Our objective was to test the hypothesis that differences in degree and pattern of dyssynchony exist in narrow QRS vs. wide QRS pts. Methods We studied 277 heart failure (HF) pts with ejection fraction EF ≤ 35% referred for device therapy: 152 had QRS ≥ 120 ms for CRT and 125 with QRS <120 ms for defibrilator therapy. Ninety % had Class III HF, 59 % had ischemic disease. Dyssychrony was assessed by TDI longitudinal velocity opposing wall delay from 12 sites using 3 apical views and speckle tracking radial strain from 6 mid-ventricular sites using short axis views to assess regional time activation. Results Overall, radial mechanical activation was early in the anteroseptum and late in the posterolateral segments in all pts groups. Anteroseptal activation was significantly earlier (254±116ms*) in pts. with QRS >140 compared to those with QRS 120–140 ms (303±98ms) or QRS < 120ms (329±96ms), *p<0.05 vs other groups. Posteriolateral delay was also significantly later (474±89ms*) in pts. with QRS >140 compared to those with QRS 120–140 ms (449±66ms) or QRS < 120ms (440±75ms), *p<0.05 vs other groups. TDI, however, was just delayed in wide QRS patients. Conclusions The degree of radial dyssynchrony was related to QRS width, although the pattern of early septal and late posterolateral activation was preserved across groups. These findings may explain differences in response to CRT in narrow vs. wide QRS patients and impact future CRT considerations.