Abstract 2020: Pattern of Mechanical Dyssynchrony Differs in Heart Failure with Narrow and Wide QRS
Background: Mechanical dyssynchrony can be present in heart failure with narrow QRS (HF-nQRS). However, little is known about its pattern and degree of dyssynchrony as compared to heart failure with wide QRS (>130msec) (HF-wQRS).
Methods: Conventional B-mode images were obtained using Vivid 7 (GE Vingmed, Norway) on normal controls (n=26), HF-wQRS (n=16, EF 19.5±7.8%, LBBB, QRS 161.3±24.5msec) and HF-nQRS (n=61, EF 23.3±6.5%, QRS 101.4±12.9msec). Using speckle tracking software (EchoPAC PC, GE, Norway), radial strain waveforms were obtained from six segments of mid-short axis views. Standard deviation (SD) of time to peak radial strain (tErr) was calculated as a numerical variance of timing. Magnitude and direction of net timing vector were sought as a vector-weighed variance of timing when each tErr value was assigned to each segment (Fig 1⇓).
Results: From analysis of normal controls, upper limit of normal values for SD-tErr and magnitude of vector were 50.1msec and 26.7msec. Using these cut-off values, 72–75% of HF-nQRS appeared to have dyssynchrony, 100% of HF-wQRS showed dyssynchrony. However, direction of net vector in HF-wQRS group points toward lateral-inferior segments (−44.3± 77.5 deg.) whereas direction of vector in HF-nQRS was scattered throughout the ventricle. Only 30% (19/61) in HF-nQRS group points toward similar directions as observed in HF-wQRS group (Fig 2⇓).
Conclusion: Although most patients of HF-nQRS showed evidence of dyssynchrony, the pattern of dyssynchrony is different from that found in patients of HF-wQRS according to the direction of net vector. Vector-weighed approach could provide detailed information about mechanical dyssynchrony.