Echocardiographic Effects of Changing Atrioventricular Delay in Cardiac Resynchronization Therapy Based on Displacement

Current role of echocardiography in cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure and left ventricular systolic dysfunction. Patients are usually assessed by echocardiography, which provides a number of anatomical and functional information used for cardiac dyssynchrony assessment, prognostic stratification, identification of the optimal site of pacing in the left ventricle, optimization of the CRT device, and patient follow-up. Compared to other cardiac imaging techniques, echocardiography has the advantage to be non-invasive, repeatable, and safe, without exposure to ionizing radiation or nefrotoxic contrast. In this article, we review current evidence about the role of echocardiography before, during, and after the implantation of a CRT device.

Simple regional strain pattern analysis to predict response to cardiac resynchronization therapy: rationale, initial results, and advantages

BACKGROUND

A classical strain pattern of early contraction in one wall and prestretching of the opposing wall followed by late contraction has previously been associated with left bundle branch block (LBBB) activation and short-term response to cardiac resynchronization therapy (CRT). Aims of this study were to establish the long-term predictive value of an LBBB-related strain pattern and to identify changes in contraction patterns during short-term and long-term CRT.

METHODS AND RESULTS

Sixty-seven patients with standard CRT criteria were prospectively enrolled between early 2009 and late 2010. Echocardiography including regional strain analysis by 2-dimensional speckle tracking was performed 1 week before implantation, at day 1, and 6 months after. Response was defined as a decrease in left ventricular end-systolic volume ≥ 15%. The predictive ability of a classical pattern was compared with time-to-peak measurements from velocity and deformation analysis. Forty-three patients (65%) were classified as responders. The presence of a classical pattern showed 91% specificity and 95% sensitivity for response and performed significantly better than time-to-peak parameters in prediction of response to CRT (P < .001, all). In responders, CRT acutely increased septal longitudinal peak systolic strain (-8.7% ± 3.6% to -11.1% ± 3%, P < .001) but not in nonresponders.

CONCLUSIONS

The classical pattern is highly predictive of response to CRT and superior to time-to-peak methods. Patients who obtain long-term reverse remodeling are characterized by short-term reversal of the classical strain pattern. These findings emphasize the value of recognizing potentially reversible strain patterns in selection of CRT candidates.

Myocardial performance is reduced immediately prior to ventricular ectopy

BACKGROUND

We recently demonstrated local voltage potentials indicating conduction impairment and block in the sinus beats preceding ventricular premature beats (VPBs) originating in the ventricular outflow tracts.

OBJECTIVE

The purpose of this study was to test the hypothesis that impairment of impulse conduction would also lead to changes in the contractile performance of sinus beats preceding ventricular ectopy using Tissue Doppler echocardiography.

METHODS

Twenty-three consecutive patients with VPBs were examined in the apical 4-chamber view with a frame rate of 150 Hz (GE VIVID VII). Eleven patients had no structural heart disease, 5 had dilated cardiomyopathy, 4 had ischemic heart disease, 2 had arrhythmogenic right ventricular dysplasia, and 1 had aortic stenosis. The ectopy originated in the ventricular outflow tracts in 15 patients and in the left ventricle 8. Eleven of the patients underwent radiofrequency ablation of the VPBs.

RESULTS

Tissue Doppler imaging demonstrated a highly statistically significant decrease in myocardial performance in the last sinus beat before the VPB compared to earlier sinus beats. Thus, ejection time (time to peak end-systolic contraction) and peak systolic velocity shortened significantly (P <.001 for both) with a subsequent reduction in systolic shortening (end-systolic displacement; P <.001).

CONCLUSION

Ventricular ectopy is preceded by a significant decrease in myocardial performance in the last sinus beat preceding VPBs as observed in consecutive patients with a broad variety of heart conditions pointing to a mutual underlying electrical mechanism (ie, localized conduction block confined to an area surrounding the ectopic pacemaker).