Peak longitudinal strain delay is superior to TDI in the selection of patients for resynchronisation therapy

Is CRT Optimization Obsolete? A Referral Center's Experience

Background

Cardiac resynchronization therapy (CRT) is a well-established therapy for patients with heart failure (HF). However, 30% of HF patients do not show any improvement in clinical status after CRT implantation. In this study, we report our echocardiography-based CRT optimization methodology, in daily practice at our CRT referral center.

Methods

We included 350 ambulatory patients, who were referred to our center for optimization after CRT implantation. A protocol-driven echocardiographic approach for adjusting mechanical dyssynchrony, whereby adjusting for ventriculoventricular (VV) delays with strain and atrioventricular (AV) delays with Doppler echocardiography was performed. We defined changes in left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) classes as outcome variables in the evaluation of the CRT outcomes.

Results

Optimization was obtained in 288 (82%) patients. VV and AV timings were adjusted to 61% and 51%, respectively. In 3%, biventricular pacing was turned off and in 3% left ventricular (LV) only pacing was programmed. The LVEF and NYHA class showed significant improvements in all patients who underwent CRT optimization.

Conclusions

CRT optimization remains valuable in improving LVEF and functional status measured using the NYHA class in all patients receiving CRT devices.

Peak longitudinal strain delay is superior to TDI in the selection of patients for resynchronisation therapy

BACKGROUND

Mechanical dyssynchrony has proven to be superior to QRS duration in predicting response to cardiac resynchronisation therapy (CRT). Whether time to peak longitudinal strain delay between the mid-septum and mid-lateral left ventricular wall better predicts CRT response than tissue Doppler imaging (TDI) is unclear. This study compares the value of the two methods for the assessment of mechanical dyssynchrony and prediction of CRT responders.

METHODS

66 clinical responders and 17 nonresponders to CRT with severe systolic heart failure (LVEF <35%), New York Heart Association classification III or IV and a wide QRS >130 ms with left bundle branch block were evaluated by peak longitudinal strain and TDI. Doppler echocardiograms and electromechanical time delay (EMD) intervals were acquired before and after pacemaker implantation.

RESULTS

In all responders EMD measured by peak longitudinal strain was >60 ms before implantation, compared with 76% of the patients measured by TDI. Nonresponders had EMD <60 ms measured by both techniques. Only peak longitudinal strain delay showed shortened values in every responder postimplantation and demonstrated the most significant reduction and could predict responders to CRT. However, EMD measured by TDI did not diminish in 30% of the positive clinical responders. Nonresponders showed worsening of the EMD with peak longitudinal strain, but not with TDI.

CONCLUSIONS

Responders to CRT can be excellently predicted if EMD before implantation determined by peak longitudinal strain delay is >60 ms. Peak longitudinal strain delay appears to be superior to TDI to predict the response to CRT. (Neth Heart J 2010;18:574-82.).