Abstract 9619: Identification of Response to Cardiac Resynchronization Therapy by Radial Strain: Influence of Cardiomyopathy Type
Background: The use of speckle tracking derived radial strain by echocardiography (echo) to predict response to cardiac resynchronization therapy (CRT) has yielded variable results. We aimed to examine factors influencing the usefulness of radial dyssynchrony after CRT to evaluate CRT response.
Method: Serial assessments of radial dyssynchrony by speckle tracking strain were performed after CRT in 98 patients (49 non-ischemic and 49 ischemic etiology) who were followed in our multidisciplinary clinic. Radial dyssynchrony (RD) was defined as a difference in time to peak strain of ≥130ms between anteroseptum and posterior wall (AS-P delay) at the mid LV level. Response to CRT was defined as a decrease in LV end systolic volume (ESV) of ≥15% or absolute increase in LVEF of >5% on 6 month echo compared to baseline.
Results: There was no difference in baseline EF between 66 responders and 32 nonresponders (25 ± 6 vs 24 ± 6 %; p=0.540). LV ESV index differed at baseline between groups (75 ± 24 vs 90± 31 ml/m2; p=0.017). For the total population, AS-P delay was not different on 1st follow up echo (echo 1, 54 ± 23 days) and 2nd follow up echo (echo 2, 215 ± 42 days) after CRT (132 ± 90 vs 126 ± 104 ms; p=NS). The prevalence of RD decreased over time (echo 1 vs echo 2, 49% vs 41%; p=0.000). In responders, the AS-P delay was reduced at echo 2 compared to echo 1 (123 ± 85 vs 93 ± 73 ms; p= 0.011). For the nonresponders, the AS-P delay showed a trend to increase (147 ± 96 vs 191 ± 128 ms; p=0.091). The improvement in AS-P delay in responders was due to non-ischemic cardiomyopathy responders (117 ± 83 to 74 ± 51 ms; p=0.003) as no change was noted in ischemic etiology responders (134 ± 90 vs 123 ± 88 ms; p=NS). The prevalence of RD also decreased in responders over time (44% vs 25%; p=0.001) due to non-ischemic etiology responders (40% vs 14%; p = 0.005). Nonresponders showed increased prevalence of RD over time (59% vs 72%, p=0.000).
Conclusion: Serial RD assessment by speckle tracking after CRT is feasible and correlates well with other measures of CRT response in non-ischemic cardomyopathy patients while it appear to be of limited value in ischemic cardiomyopathy. Thus, when examining the value of AS-P delay in CRT populations, the prevalence of cardiomyopathy type is critical.
- © 2011 by American Heart Association, Inc.