This article is more than 5 years old. Information may no longer be current.
Dyssynchrony indices not predictive of response to CRT
Miyazaki C. Circ Heart Fail. 2010;3:565-573.
Click Here to Manage Email Alerts
New data from Circulation: Heart Failure suggest that dyssynchrony indices should not be used to guide use of cardiac resynchronization therapy in patients with HF.
“Multiple small retrospective studies suggested that various echocardiographic dyssynchrony indices have high sensitivity and specificity for identifying patients with a favorable response to cardiac resynchronization therapy (CRT),” the researchers commented in their study. “However, the multicenter prospective Predictors of Response to CRT (PROSPECT) trial was not able to identify any echocardiographic dyssynchrony parameter that added significant incremental value to the current simple QRS duration and clinical selection criteria for CRT.”
To help further clarify the role of dyssynchrony indices in CRT, the researchers performed a comprehensive, prospective, single-center trial enrolling 184 patients with HF with anticipated CRT from September 2005 to September 2007.
The final study population (n=131) had wide QRS and left ventricular ejection fraction <35%. All patients underwent clinical evaluation, echocardiography, Minnesota Living with Heart Failure Questionnaire, 6-minute walk distance and cardiopulmonary exercise testing for measurement of peak oxygen consumption before implantation and 6 months after implantation. Researchers analyzed 14 dyssynchrony indices by timing intervals (98%), tissue velocity (96%), M-mode (94%), tissue Doppler strain (92%), 2-D speckle strain (65%-86%) and 3-D echocardiography (79%).
At the 6-month follow-up, researchers reported reverse remodeling (end-systolic volume reduction >15%) in 55% of patients and more frequently in those without vs. with ischemic cardiomyopathy (71% vs. 42%; P=.002). Dyssynchrony index did not predict reverse remodeling in nonischemic cardiomyopathy, whereas indices derived using ischemic cardiomyopathy M-mode (area under curve [AUC], 0.67), tissue Doppler strain (AUC, 0.79), and isovolumic time (AUC, 0.76) were predictive of reverse remodeling (P<.05 for all).
Additionally, no indices assessed by Minnesota Living with Heart Failure Questionnaire, 6-minute walk distance or peak oxygen consumption were predictive of clinical response.
Limitations of note included lack of paired data for clinical response variables in some patients, the possibility of differences in data analysis between this and other studies, as well as the possibility that adjustment for LV lead position relative to dyssynchrony and scar may have improved the predictive value of mechanical dyssynchrony for reverse remodeling.
“The current findings, in concert with those of the PROSPECT and Cardiac Resynchronization in Heart Failure studies, indicate that the decision to use CRT should be based on standard guidelines and do not support a routine clinical use of any echocardiographic dyssynchrony indices to select patients for CRT,” the researchers wrote. “Although superior measures of mechanical dyssynchrony may be developed, the consistent findings observed with the large number of parameters assessed in this study do not engender optimism that use of CRT can be further refined by measurement of mechanical dyssynchrony in patients with advanced symptoms, low ejection fraction and conduction delay.”
Future studies, they added, should focus on further characterizing the clinical and laboratory features of the patients who do not respond to CRT.
 |
Follow CardiologyToday.com on Twitter. |