Author + information
- Received May 2, 2018
- Revision received July 5, 2018
- Accepted July 13, 2018
- Published online September 12, 2018.
- John Gorcsan III, MDa,∗ (, )
- Christopher P. Anderson, MPHb,
- Bhupendal Tayal, MD, PhDc,
- Masataka Sugahara, MDc,
- John Walmsley, PhDd,
- Randall C. Starling, MD, MPHe and
- Joost Lumens, PhDf,g
- aWashington University in St. Louis, St. Louis, Missouri
- bBiostatistics Group, Medtronic Incorporated, Minneapolis, Minnesota
- cThe University of Pittsburgh, Pittsburgh, Pennsylvania
- dCARIM School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, the Netherlands
- eThe Cleveland Clinic, Cleveland, Ohio
- fCARIM School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, the Netherlands
- gL'Institut de Rythmologie et Modélisation Cardiaque (IHU-LIRYC), Université de Bordeaux, Pessac, France
- ↵∗Address for correspondence:
Dr. John Gorcsan III, Division of Cardiology, Washington University in St. Louis, 660 South Euclid Avenue, Campus Box 8086, St. Louis, Missouri 63110.
Objectives In this study, the authors tested the hypotheses that the systolic stretch index (SSI) developed by computer modeling and applied using echocardiographic strain imaging may characterize the electromechanical substrate predictive of outcome following cardiac resynchronization therapy (CRT). They included patients with QRS width 120 to 149 ms or non-left bundle branch block (LBBB), where clinical uncertainty for CRT exists. They further tested the hypothesis that global longitudinal strain (GLS) has additional prognostic value.
Background Response to CRT is variable. Guidelines favor patient selection by electrocardiographic LBBB with QRS width ≥150 ms.
Methods The authors studied 442 patients enrolled in the Adaptive CRT 94-site randomized trial with New York Heart Association functional class III–IV heart failure, ejection fraction ≤35%, and QRS ≥120 ms. A novel computer program semiautomatically calculated the SSI from strain curves as the sum of posterolateral prestretch percent before aortic valve opening and the septal rebound stretch percent during ejection. The primary endpoint was hospitalization for heart failure (HF) or death, and the secondary endpoint was death over 2 years after CRT.
Results In all patients, high longitudinal SSI (≥ group median of 3.1%) was significantly associated with freedom from the primary endpoint of HF hospitalization or death (hazard ratio [HR] for low SSI: 2.17; 95% confidence interval [CI]: 1.45 to 3.24, p < 0.001) and secondary endpoint of death (HR for low SSI: 4.06; 95% CI: 1.95 to 8.45, p < 0.001). Among the 203 patients with QRS 120 to 149 ms or non-LBBB, those with high longitudinal SSI (≥ group median of 2.6%) had significantly fewer HF hospitalizations or deaths (HR for low SSI: 2.08; 95% CI: 1.27 to 3.41, p = 0.004) and longer survival (HR for low SSI: 5.08; 95% CI: 1.94 to 13.31, p < 0.001), similar to patients with LBBB ≥150 ms. SSI by circumferential strain had similar associations with clinical outcomes, and GLS was additive to SSI in predicting clinical events (p = 0.001).
Conclusions Systolic stretch by strain imaging characterized the myocardial substrate associated with favorable CRT response, including in the important patient subgroup with QRS width 120 to 149 ms or non-LBBB. GLS had additive prognostic value.
This study was supported by an investigator-initiated grant from Medtronic, Inc. Dr. Gorcsan was supported, in part, by research grants from Medtronic, EBR Systems, GE Medical Systems, and Hitachi Medical, Inc. Mr. Anderson is employed as a biostatistician by Medtronic, Inc. Dr. Starling has received research support from Abbott and Medtronic. Dr. Lumens was funded through a personal grant within the Dr. E. Dekker framework of the Dutch Heart Foundation (grant 2015T082). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received May 2, 2018.
- Revision received July 5, 2018.
- Accepted July 13, 2018.
- 2018 American College of Cardiology Foundation
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