Advantage of optimizing V-V timing in cardiac resynchronization therapy devices.
BACKGROUND
There is little consensus as to the benefits of interventricular (V-V) timing optimization in cardiac resynchronization therapy (CRT). A variety of parameters are currently used to optimize device timing. This study was designed to investigate the potential advantage of using 3D ejection fraction (EF) and aortic velocity-time integral (VTI) as measures of global left ventricular (LV) function to optimize ventricular activation in CRT devices.


METHODS
Seventy-four patients seen in the Optimization Clinic with adequate echocardiographic images were included. Three aortic VTI and two 3D EF values were recorded at five V-V settings and the average value used. Aortic VTI and 3D EF were classified as the best, worst, and simultaneous setting values. Data were analyzed using a two-tailed paired t-test.


RESULTS
Comparing the best to worst V-V timing settings, VTI improved by 4.7 ± 7.5 cm (P < 0.0001) and 3D EF by 9.9%± 5.7% (P < 0.0001). Comparing the simultaneous setting to the best V-V timing setting, VTI improved by 2.4 ± 2.1 cm (P < 0.0001) and 3D EF by 3.8%± 4.9% (P < 0.0001). Aortic VTI improved in 85% of patients and 3D EF improved in 72%. However, only 26% of the patients had the same optimal setting using aortic VTI and 3D EF yielding an r(2) value of 0.003.


CONCLUSIONS
Individualized echocardiographic V-V optimization of CRT devices improves global LV function as measured by aortic VTI and 3D EF. Substantial differences in function were seen over an 80-ms range of V-V timing and optimization resulted in improved LV function in the majority of patients.
Zena and Michael A. Wiener Cardiovascular Institute, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA.
W Lane
WL
Duvall
Riple
R
Hansalia
Melanie N
MN
Wijetunga
Samantha
S
Buckley
Avi
A
Fischer
D000368:Aged; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D058409:Cardiac Resynchronization Therapy Devices; D009202:Cardiomyopathies / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013318:Stroke Volume; D016896:Treatment Outcome; D014463:Ultrasonography