Background: The present study was conducted to assess the clinical applicability of a novel method of displaying left ventricular (LV) function and dyssynchrony using Doppler tissue imaging (DTI) in patients with dilated cardiomyopathy with wide or narrow QRS complexes.
Methods: The study included 28 patients with wide QRS complexes, 36 with narrow QRS complexes, and 55 apparently healthy subjects (controls). The time to peak velocities (TPVs) obtained from 6 basal LV segments were assumed to be "vectors" and aligned radially such that each terminal point was directed to the corresponding LV segment. The resulting hexagonal graph covered the following aspects of LV function and dyssynchrony: (1) percentage area of the hexagon, the area divided by the overall graph area, reflecting global LV systolic function; (2) the net-delay magnitude of mechanical contraction, the length of the composite vector for the 6 vectors; and (3) delayed contraction site, the graphical position of the composite vector.
Results: The percentage area of the hexagon was correlated with the pre-ejection period (r = 0.80; P < .001) and LV ejection fraction (r = -0.66; P < .001). The net-delay magnitude was longest in patients with wide QRS complexes and shortest in controls (123 +/- 61 vs 36 +/- 27 ms; P < .001). LV mechanical dyssynchrony on the basis of the new method (net-delay magnitude > 90 ms) was detectable in 68% of patients with wide QRS complexes and in 39% of those with narrow QRS complexes. The percentages were similar to those obtained using conventional DTI-derived indexes (the standard deviation and dispersion of TPVs in the 12 myocardial segments). The new method, moreover, revealed that patients with wide QRS complexes had delayed contraction sites located more often between the lateral and inferior wall segments than controls (68% vs 35%; P < .001).
Conclusions: The new displaying method permits at-a-glance recognition of LV function and dyssynchrony. Whether the method can be used to predict resynchronization awaits further study.