Original Research
Real-Time 3D Echo in Patient Selection for Cardiac Resynchronization Therapy

https://doi.org/10.1016/j.jcmg.2010.09.021Get rights and content
Under an Elsevier user license
open archive

Objectives

This study investigated the use of 3-dimensional (3D) echo in quantifying left ventricular mechanical dyssynchrony (LVMD), its interhospital agreement, and potential impact on patient selection.

Background

Assessment of LVMD has been proposed as an improvement on conventional criteria in selecting patients for cardiac resynchronization therapy (CRT). Three-dimensional echo offers a reproducible assessment of left ventricular (LV) structure, function, and LVMD and may be useful in selecting patients for this intervention.

Methods

We studied 187 patients at 2 institutions. Three-dimensional data from baseline and longest follow-up were quantified for volume, left ventricular ejection fraction (LVEF), and systolic dyssynchrony index (SDI). New York Heart Association (NYHA) functional class was assessed independently. Several outcomes from CRT were considered: 1) reduction in NYHA functional class; 2) 20% relative increase in LVEF; and 3) 15% reduction in LV end-systolic volume. Sixty-two cases were shared between institutions to analyze interhospital agreement.

Results

There was excellent interhospital agreement for 3D–derived LV end-diastolic and end- systolic volumes, EF, and SDI (variability: 2.9%, 1%, 7.1%, and 7.6%, respectively). Reduction in NYHA functional class was found in 78.9% of patients. Relative improvement in LVEF of 20% was found in 68% of patients, but significant reduction in LV end-systolic volume was found in only 41.5%. The QRS duration was not predictive of any of the measures of outcome (area under the curve [AUC]: 0.52, 0.58, and 0.57 for NYHA functional class, LVEF, and LV end-systolic volume), whereas SDI was highly predictive of improvement in these parameters (AUC: 0.79, 0.86, and 0.66, respectively). For patients not fulfilling traditional selection criteria (atrial fibrillation, QRS duration <120 ms, or undergoing device upgrade), SDI had similar predictive value. A cutoff of 10.4% for SDI was found to have the highest accuracy for predicting improvement following CRT.

Conclusions

The LVMD quantification by 3D echo is reproducible between centers. SDI was an excellent predictor of response to CRT in this selected patient cohort and may be valuable in identifying a target population for CRT irrespective of QRS morphology and duration.

Key Words

cardiac resynchronization therapy
left bundle branch block
3-dimensional echocardiography

Abbreviations and Acronyms

AUC
area under the curve
CRT
cardiac resynchronization therapy
ECG
electrocardiography
ICC
intraclass correlation coefficient
LBBB
left bundle branch block
LVEF
left ventricular ejection fraction
LVESV
left ventricular end-systolic volume
LVMD
left ventricular mechanical dyssynchrony
NYHA
New York Heart Association
QRSd
QRS duration
ROC
receiver-operator characteristic
RT3DE
real-time 3-dimensional echocardiography
SDI
systolic dyssynchrony index

Cited by (0)

Drs. Kapetanakis and Bhan have received honoraria from Philips Medical Systems for teaching. Dr. Murgatroyd is a member of the advisory boards for Medtronic, Boston Scientific, and Sorin, and has received honoraria from Medtronic and Sorin as well as research support from Medtronic. Dr. Kearney has received research support from Medtronic. Dr. Gall has received honoraria and unrestricted research grants from St. Jude, Medtronic, Sorin ELA, and Boston Scientific. Dr. Zhang has reported that he has no relationships to disclose. Prof. Yu has received minor research support from Philips. Dr. Monaghan has received honoraria from Philips Medical Systems for teaching and research support from Philips, GE Healthcare, and TomTec.