The Role of Echocardiography in the Optimization of Cardiac Resynchronization Therapy: Current Evidence and Future Perspectives

Abstract

Background:Cardiac resynchronization therapy (CRT) has become a mainstay in the management of heart failure. Up to one-third of patients who received resynchronization devices do not experience the full benefits of CRT. The clinical factors influencing the likelihood to respond to the therapy are wide QRS complex, left bundle branch block, female gender, non-ischaemic cardiomyopathy (highest responders), male gender, ischaemic cardiomyopathy (moderate responders) and narrow QRS complex, non-left bundle branch block (lowest, non-responders). Objective:This review provides a conceptual description of the role of echocardiography in the optimization of CRT. Method:A literature survey was performed using PubMed database search to gather information regarding CRT and echocardiography. Results:A total of 70 studies met selection criteria for inclusion in the review. Echocardiography helps in the initial selection of the patients with dyssynchrony, which will benefit the most from optimal biventricular pacing and provides a guide to left ventricular (LV) lead placement during implantation. Different echocardiographic parameters have shown promise and can offer the possibility of patient selection, response prediction, lead placement optimization strategies and optimization of device configurations. Conclusion:LV ejection fraction along with specific electrocardiographic criteria remains the cornerstone of CRT patient selection. Echocardiography is a non-invasive, cost-effective, highly reproducible method with certain limitations and accuracy that is affected by measurement errors. Echocardiography can assist with the identification of the appropriate electromechanical substrate of CRT response and LV lead placement. The targeted approach can improve the haemodynamic response, as also the patient-specific parameters estimation.

The role of contractile reserve by stress test echocardiography for predicting cardiac resynchronization therapy responder: systematic review and meta-analysis

“…ESC guidelines suggest an exercise or pharmacological SE for the assessment of myocardial viability and/or myocardial ischemia but do not mention SE to identify CRT responder [3]. Mechanical dyssynchrony has been described as the regional contraction discrepancy or an uncoordinated, unequaled regional myocardial motion [31]. Left bundle branch block (LBBB) may trigger Figure 6: Forest plots benefit of cardiac resynchronization therapy towards ischemic etiology a dyssynchrony.…”

“…Septal flash and apical rocking are two parameters that are widely recommended to assess mechanical dyssynchrony. However, these two parameters have disadvantages, such as; apical rocking sometimes depend on the RV function and there are differences between observers, also there is bias in translation of continuous process to on/off phenomenon in septal flash measurement [31]. Most studies investigated wall movement with echocardiography did not specify the cause of dyssynchronous conditions, weather it was due to electrical activation delayed (broad QRS) or the loading and/or contractile properties.…”

Optimization of CRT programming using non‐invasive electrocardiographic imaging to assess the acute electrical effects of multipoint pacing

“…In three of our cohorts, the degree of biventricular resynchronization was further enhanced with iterative echo guided optimization of the AV and VV intervals. Whilst there is evidence to support this strategy, 14,15,17 larger studies have failed to consistently prove it's efficacy. 18,19 Our results would suggest that optimization of the AV and VV intervals may indeed result in more effective resynchronization than can be achieved using nominal settings in a proportion of patients, but not all.…”

Systolic aortic root motion predicts response to cardiac resynchronization therapy

“…Currently, there was not any accepted echo technique for the identification of CRT responders, and echocardiographic dyssynchrony was not recommended as selection criteria for CRT in recent guidelines . However, some 2D and 3D speckle‐tracking echocardiography dyssynchrony findings has been studied to predict CRT response and optimal LV lead placement …”

“…However, some 2D and 3D speckle-tracking echocardiography dyssynchrony findings has been studied to predict CRT response and optimal LV lead placement. [19][20][21] Now, the main condition for CRT is an electrical activation delay which is assessed as QRS duration and bundle branch block. The importance of the contraction pattern is independent of QRS duration; therefore, it could be particularly beneficial for selection of patients with inappropriate criteria for CRT.…”