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LV Global Longitudinal Strain and Secondary MR Prognosis
Study Questions:
Is there prognostic value of left ventricular (LV) global longitudinal strain (GLS) over LV ejection fraction (LVEF) among patients with secondary mitral regurgitation (MR)?
Methods:
At a single center, a total of 650 patients (mean 66 ± 11 years of age, 68% men, 52% ischemic etiology, LVEF 29 ± 10%, LV end-diastolic volume index 107 ± 41 ml/m2, LV GLS 7.2 [5.2–9.9]) with moderate or severe secondary MR were retrospectively studied. The study population was subdivided based on the LV GLS absolute value (removing the conventional negative value of GLS data) at which the hazard ratio (HR) for all-cause mortality was >1 using a spline curve analysis (LV GLS <7.0% [impaired LV systolic function] vs. LV GLS ≥7.0% [preserved LV systolic function]). The primary endpoint was all-cause mortality.
Results:
During a median follow-up of 56 months (interquartile range, 28-106 months), 334 (51%) patients died. Patients with a more impaired LV GLS showed significantly higher mortality rates at 1-, 2-, and 5-year follow-up (13%, 23%, and 44%, respectively) when compared with patients with more preserved LV systolic function (5%, 14%, and 31%, respectively). On multivariable analysis, LV GLS (absolute value) <7.0% was associated with increased mortality (HR, 1.337; 95% confidence interval [CI], 1.038-1.722; p = 0.024), whereas LVEF ≤30% was not (HR, 1.055; 95% CI, 0.794-1.403; p = 0.711).
Conclusions:
Among patients with secondary MR, impaired LV GLS was independently associated with an increased risk for all-cause mortality, whereas LVEF was not. The authors concluded that LV GLS may be useful in the risk stratification of patients with secondary MR.
Perspective:
LVEF is load dependent, and therefore, overestimates LV systolic function in the setting of significant MR; in contrast, LV GLS is a less load-dependent measure of LV systolic function. LV GLS previously has been shown to be a more sensitive marker for LV systolic dysfunction than LVEF among patients with nonischemic dilated cardiomyopathy; to have incremental prognostic value among patients with heart failure; and to have value in risk stratification among patients with primary MR or aortic regurgitation. This study suggests that LV GLS also has prognostic value over LVEF among a mixed (ischemic and nonischemic) population of patients with cardiomyopathy and moderate or severe secondary MR. Importantly, GLS data are vendor and software specific, so the values listed in this study cannot be extrapolated to other centers. From a methodological standpoint, the present study did not include quantitative data for MR; and, importantly, the threshold data used to define a significant abnormality in GLS was tested in the same population from which it was derived. From the standpoint of clinical practice, there were significant differences in LV size (LV end-diastolic volume index 92 ± 31 ml/m2 [GLS ≥7.0%] vs. 124 ± 45 ml/m2 [GLS <7.0%], p < 0.001) and LVEF (33 ± 11 ml/m2 [GLS ≥7.0%] vs. 23 ± 7 ml/m2 [GLS <7.0%], p < 0.001) between groups; and the present study does not suggest that any intervention alters prognosis based on GLS data. It makes sense that LV GLS may provide important prognostic data among patients with cardiomyopathy and secondary MR; additional study will be required to move GLS data into clinical decision-making for patients with secondary MR.
Clinical Topics: Congenital Heart Disease and Pediatric Cardiology, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Valvular Heart Disease, Congenital Heart Disease, CHD and Pediatrics and Imaging, CHD and Pediatrics and Prevention, CHD and Pediatrics and Quality Improvement, Acute Heart Failure, Mitral Regurgitation
Keywords: Aortic Valve Insufficiency, Cardiomyopathies, Cardiomyopathy, Dilated, Diagnostic Imaging, Heart Failure, Heart Valve Diseases, Mitral Valve Insufficiency, Risk Assessment, Stroke Volume, Systole, Ventricular Function, Left, Heart Defects, Congenital
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