Author + information
- Chimène Zaïani, MD,
- Maude Pagé, MD and
- Frédéric Poulin, MD, MSc∗ ()
- ↵∗Hôpital du Sacré-Coeur de Montréal, Université de Montréal, 5400 Boulevard Gouin Ouest, Montréal, Québec, Canada H4J 1C5
In the December 1, 2015, issue of iJACC, Sengeløv et al. (1) retrospectively analyzed left ventricular strain in a cohort of 1,065 heart failure with reduced ejection fraction patients. Global longitudinal strain (GLS) was found to be the only independent echocardiographic predictor of all-cause mortality after a median follow-up of 40 months, and added incremental prognostic value over conventional parameters. First, we wish to recognize the extensive work achieved by the authors, who sought to refine risk stratification among heart failure with reduced ejection fraction patients by studying this contemporary echocardiographic tool.
Although multisocietal efforts are being made to implement GLS as a standardized measure (2), we raise concern regarding the reproducibility of retrospectively performed strain measurements in the study population, which included patients with ischemic cardiomyopathy (57%), regional wall motion abnormalities, and dilated ventricles. We believe that it is of paramount importance that the authors clarify how the width of the region of interest was adjusted in cases of nonuniformity in wall thickness (e.g., anterior wall thinning from myocardial infarction), considering that strain measurements with this vendor are derived from tracking of the entire myocardial wall. For their findings to be clinically relevant to practitioners, it would be of great value if the authors could give us case examples that presented this technical challenge. Similarly, providing an interobserver and intraobserver analysis as well as test-retest variability for GLS in a subset of randomly selected patients would be reassuring to the clinicians and echocardiographic laboratories who are considering adding this parameter to their imaging protocol for a similar patient population.
Also, we would appreciate if the authors could further comment on the pathophysiological basis underlying the superiority of GLS over left ventricular ejection fraction to predict mortality. Could this association be driven by patients with smaller hypertrophied ventricles in whom GLS might overcome the limitations of left ventricular ejection fraction in the assessment of systolic function and better predict clinical events? In the same vein, we are questioning the rationale for not including left ventricular dimensions in the Cox proportional hazard models. Regarding the outcomes, although we understand that the data may have been difficult to collect, we believe that using all-cause mortality instead of cardiovascular mortality, which would have made intuitive sense in this cohort, further mitigates the conclusions that can be derived from the results. We acknowledge that GLS is an echocardiographic tool with a prognostic potential that could be used in our heart failure population, and we are hoping to better understand its applicability with the help of the authors’ answers.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2016 American College of Cardiology Foundation