Strain rate dispersion index can predict changes in left ventricular volume and adverse cardiac events following cardiac resynchronization therapy.
BACKGROUND
We previously reported that the strain rate dispersion index (SRDI), an index of left ventricular (LV) contractility loss because of mechanical dyssynchrony, better predicted the acute response to cardiac resynchronization therapy (CRT) than time-delay indices. However, it remains unclear whether the SRDI can predict the chronic response. Additionally, the SRDI needs to be simplified for use in clinical practice.


RESULTS
Echocardiography was performed in 40 heart failure patients who underwent CRT. The SRDI, the average of segmental peak systolic strain rates minus global peak systolic strain rate, was calculated, together with strain-derived time-delay indices (St-SD) in the longitudinal, circumferential and radial directions using a speckle-tracking method. As simplified indices, the longitudinal parameters were calculated from the apical 4-chamber view in addition to 3 apical views. LV end-systolic volume (ESV) significantly decreased 6 months after CRT. Although circumferential St-SD and all SRDIs correlated with the changes in ESV (ΔESV), multivariate analysis revealed that the circumferential SRDI was the single independent determinant of ΔESV. During the 20±14 months after CRT, cardiac events occurred in 14 patients. Kaplan-Meier analyses revealed that all SRDIs were significant predictors of cardiac events whereas none of St-SDs was.


CONCLUSIONS
The SRDI predicted the reduction in both LV volume and cardiac events after CRT better than time-delay indices. Additionally, a simplified SRDI could be as good a predictor of CRT response as the original.
Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine.
Hiroyuki
H
Iwano
Satoshi
S
Yamada
Masaya
M
Watanabe
Hirofumi
H
Mitsuyama
Kazuya
K
Mizukami
Hisao
H
Nishino
Shinobu
S
Yokoyama
Sanae
S
Kaga
Kazunori
K
Okada
Mutsumi
M
Nishida
Hisashi
H
Yokoshiki
Taisei
T
Mikami
Hiroyuki
H
Tsutsui
D000368:Aged; D058406:Cardiac Resynchronization Therapy; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000401:mortality / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D013599:Systole; D016277:Ventricular Function, Left