What is the clinical evidence from this study?

Study design: Cohort. Population: Advanced Chronic Kidney Disease (n=183). Intervention: Global Longitudinal Strain (GLS) vs. Ejection Fraction (EF). Primary outcome: All-cause mortality (HR 1.09, 95% CI 1.02-1.16, p=0.01).

May 15, 2015Open Access

Left Ventricular Global Longitudinal Strain (GLS) Is a Superior Predictor of All-Cause and Cardiovascular Mortality When Compared to Ejection Fraction in Advanced Chronic Kidney Disease

RKRathika KrishnasamySunshine Coast University Hospital NINicole M. IsbelThe University of Queensland CHCarmel M. HawleyThe University of Queensland

Key Result

Global longitudinal strain was a significant independent predictor of all-cause mortality (HR 1.09) and cardiovascular mortality (HR 1.16) in patients with advanced chronic kidney disease, showing superior predictive power compared to ejection fraction.

Study Design

Type

Cohort (n=183)

Multicenter

Structured PICO

Does echocardiographic global longitudinal strain (GLS) better predict all-cause and cardiovascular mortality compared to ejection fraction in patients with advanced chronic kidney disease?

Population

183 adults with advanced chronic kidney disease (stages 4, 5, and 5D), followed for an average of 7.8 years to assess the prognostic value of global longitudinal strain.

Exposure

Echocardiographic global longitudinal strain (GLS) calculated using 2-dimensional speckle tracking

Comparator

Ejection fraction (EF) measured using Simpson's biplane method

Outcome

All-cause and cardiovascular (CV) mortalityhard clinical

Main Result

Hazard Ratio: 1.09 (95% CI 1.02–1.16)

p-value: p=0.01

Limitations

Unable to conduct a subgroup analysis according to stages of CKD or dialysis modality due to the relative small sample sizes
No differences in mortality between subjects with preserved and impaired EF, possibly due to sample size
Did not have measures of diastolic function in majority of patients to directly compare prognostic relevance of systolic and diastolic function
Only conducted univariate analysis in patients with preserved EF due to the small number of events
Possibility of residual confounding cannot be excluded
Used resting echocardiogram and were unable to identify inducible ischemia as a predictor of mortality
Inter-vendor variability can affect GLS measurements, limiting prognostic value to the equipment used

Abstract

BACKGROUND: Echocardiographic global longitudinal strain (GLS) is increasingly recognised as a more effective technique than conventional ejection fraction (EF) in detecting subtle changes in left ventricular (LV) function. This study investigated the prognostic value of GLS over EF in patients with advanced Chronic Kidney Disease (CKD). METHODS: The study included 183 patients (57% male, 63% on dialysis) with CKD stage 4, 5 and 5Dialysis (D). 112 (61%) of patients died in a follow up of 7.8 ± 4.4 years and 41% of deaths were due to cardiovascular (CV) disease. GLS was calculated using 2-dimensional speckle tracking and EF was measured using Simpson's biplane method. Cox proportional hazard models were used to assess the association of measures of LV function and all- cause and CV mortality. RESULTS: The mean GLS at baseline was -13.6 ± 4.3% and EF was 45 ± 11%. GLS was a significant predictor of all-cause Hazard Ratio (HR) 1.09 95%; Confidence Interval (CI) 1.02-1.16; p = 0.01 and CV mortality (HR 1.16 95%; CI 1.04-1.30; p = 0.008) following adjustment for relevant clinical variables including LV mass index (LVMI) and EF. GLS also had greater predictive power for both all- cause and CV mortality compared to EF. Impaired GLS (>-16%) was associated with a 5.6-fold increased unadjusted risk of CV mortality in patients with preserved EF. CONCLUSIONS: In this cohort of patients with advanced CKD, GLS is a more sensitive predictor of overall and CV mortality compared to EF. Studies of larger populations in CKD are required to confirm that GLS provides additive prognostic value in patients with preserved EF.

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