Prognostic Relevance and Lower Limit of the Reference Range of Left Ventricular Global Longitudinal Strain

BACKGROUND: The lower limit of the reference normal range (LLN) of left ventricular global longitudinal strain (GLS) for each ultrasound software vendor and its prognostic relevance in the elderly and in asymptomatic patients at risk for heart failure (HF) remain uncertain. OBJECTIVES: In this study, the authors sought to validate the LLN of GLS for each ultrasound software vendor and its prognostic relevance in the elderly and in asymptomatic patients at risk for HF. METHODS: To identify the LLN of GLS with the use of 2-dimensional speckle-tracking transthoracic echocardiography, a meta-analysis of studies including healthy subjects was conducted, followed by a validation study in a large cohort of healthy subjects. To validate the prognostic relevance of the LLN of GLS, 2 validation cohort studies were carried out, including elderly subjects aged ≥80 years and asymptomatic ambulatory patients with preserved left ventricular ejection fraction at risk for HF. RESULTS: The meta-analysis, which included 47 studies with a total of 23,208 healthy adult subjects, identified the LLN for GLS at 16% (absolute value) across various ultrasound software vendors, including EchoPac, TomTec, and QLab. In the validation cohort study, which included 2,217 healthy adult subjects, a GLS cutoff of 16% was also identified as the LLN. Concerning the prognostic relevance of the LLN of GLS, a value of GLS <16% was significantly associated with HF hospitalization in asymptomatic ambulatory patients at risk for HF (n = 667; OR within 6 years: 5.1 95% CI: 1.5-17.0) and in elderly subjects (n = 159; OR within 2 years: 3.1 95% CI: 1.1-8.8). CONCLUSIONS: This clinical validation study provides important clinical data concerning the LLN of GLS (identified and validated at 16%) and its prognostic relevance in the elderly and in asymptomatic ambulatory patients at risk for HF.