The roles of global longitudinal strain imaging in contemporary clinical cardiology

The Clinical Applications of Left Atrial Strain: A Comprehensive Review

Left atrial (LA) strain imaging, which measures the deformation of the LA using speckle-tracing echocardiography (STE), has emerged recently as an exciting tool to help provide diagnostic and prognostic information for patients with a broad range of cardiovascular (CV) pathologies. Perhaps due to the LA's relatively thin-walled architecture compared with the more muscular structure of the left ventricle (LV), functional changes in the left atrium often precede changes in the LV, making LA strain (LAS) an earlier marker for underlying pathology than many conventional echocardiographic parameters. LAS imaging is typically divided into three phases according to the stage of the cardiac cycle: reservoir strain, which is characterized by LA filling during systole; conduit strain, which describes LA deformation during passive LV filling; and booster strain, which provides information on the LA atrium during LA systole in late ventricular diastole. While additional large-population studies are still needed to further solidify the role of LAS in routine clinical practice, this review will discuss the current evidence of its use in different pathologies and explore the possibilities of its applications in the future.

The Prognostic Role of Global Longitudinal Strain and NT-proBNP in Heart Failure Patients Receiving Cardiac Resynchronization Therapy

BACKGROUND

We aimed to evaluate whether baseline GLS (global longitudinal strain), NT-proBNP, and changes in these after cardiac resynchronization therapy (CRT) can predict long-term clinical outcomes and the echocardiographic-based response to CRT (defined by 15% relative reduction in left ventricular end-systolic volume).

METHODS

We enrolled 143 patients with stable ischemic heart failure (HF) undergoing CRT-D implantation. NT-proBNP and echocardiography were obtained before and 6 months after. The patients were followed up (median: 58 months) for HF-related deaths and/or HF hospitalizations (primary endpoint) or HF-related deaths (secondary endpoint).

RESULTS

A total of 84 patients achieved the primary and 53 the secondary endpoint, while 104 patients were considered CRT responders and 39 non-responders. At baseline, event-free patients had higher absolute GLS values (p < 0.001) and lower NT-proBNP serum levels (p < 0001) than those achieving the primary endpoint. A similar pattern was observed in favor of CRT responders vs. non-responders. On Cox regression analysis, baseline absolute GLS value (HR = 0.77; 95% CI, 0.51-1.91; p = 0.002) was beneficially associated with lower primary endpoint incidence, while baseline NT-proBNP levels (HR = 1.55; 95% CI, 1.43-2.01; p = 0.002) and diabetes presence (HR = 1.27; 95% CI, 1.12-1.98; p = 0.003) were related to higher primary endpoint incidence.

CONCLUSIONS

In HF patients undergoing CRT-D, baseline GLS and NT-proBNP concentrations may serve as prognostic factors, while they may predict the echocardiographic-based response to CRT.

Diagnostic value of reduced left atrial compliance during ergometry exercise in heart failure with preserved ejection fraction

AIMS

Diagnosis of heart failure with preserved ejection fraction (HFpEF) remains challenging in patients presenting with chronic dyspnoea. We sought to determine the diagnostic value of reduced left atrial (LA) compliance during exercise to diagnose HFpEF.

METHODS AND RESULTS

Ergometry exercise stress echocardiography was performed in 225 patients with HFpEF and 262 non-heart failure controls (non-cardiac dyspnoea [NCD]) in Protocol 1, where the diagnosis of HFpEF was defined by the HFA-PEFF algorithm. In Protocol 2, the diagnosis of HFpEF was ascertained by exercise right heart catheterization in 67 participants (49 HFpEF and 18 NCD). Speckle-tracking echocardiography was performed at rest and during exercise to determine LA compliance (ratio of LA reservoir strain to E/e'). As compared with NCD, patients with HFpEF demonstrated decreased LA reservoir strain and compliance at rest, and these differences further increased during exercise in Protocol 1. Exercise LA compliance discriminated HFpEF from NCD (area under the curve 0.87, p < 0.0001), with a superior diagnostic ability to exercise E/e' ratio (DeLong p = 0.005). Exercise LA compliance demonstrated incremental diagnostic value over clinical factors (age, systemic hypertension, and atrial fibrillation) and resting LA compliance (χ2 212.4 vs. 166.2, p < 0.0001). These findings were confirmed in Protocol 2.

CONCLUSION

Left atrial compliance during exercise demonstrated superior diagnostic ability to exercise E/e' ratio, with incremental diagnostic value over the resting LA compliance. Exercise LA compliance may enhance the diagnosis of HFpEF among patients with dyspnoea.

Fat Mass is Associated with Subclinical Left Ventricular Systolic Dysfunction in Patients with Type 2 Diabetes Mellitus Without Established Cardiovascular Diseases

INTRODUCTION

Left ventricular global longitudinal strain (GLS) is considered to be the first marker of diabetes mellitus-related subclinical cardiac dysfunction, but whether it is attributable to fat mass and distribution remains uncertain. In this study, we explored whether fat mass, especially fat mass in the android area, is associated with subclinical systolic dysfunction before the onset of cardiac disease.

METHODS

We conducted a single-center prospective cross-sectional study between November 2021 and August 2022 on inpatients of the Department of Endocrinology, Nanjing Drum Tower Hospital. We included 150 patients aged 18-70 years with no signs, symptoms, or history of clinical cardiac disease. Patients were evaluated with speckle tracking echocardiography and dual energy X-ray absorptiometry. The cutoff values for subclinical systolic dysfunction were set at a global longitudinal strain (GLS) < 18%.

RESULTS

After adjusting for sex and age, patients with GLS < 18% had a higher mean (± standard deviation) fat mass index (8.06 ± 2.39 vs. 7.10 ± 2.09 kg/m², p = 0.02), higher mean trunk fat mass (14.9 ± 4.9 vs. 12.8 ± 4.3 kg, p = 0.01), and higher android fat mass (2.57 ± 1.02 vs. 2.18 ± 0.86 kg, p = 0.02) than those in the GLS ≥ 18%. Partial correlation analysis showed that the fat mass index, truck fat mass, and android fat mass were negatively correlated with GLS after adjusting for sex and age (all p < 0.05). Adjusted for traditional cardiovascular metabolic factors, fat mass index (odds ratio [OR] 1.27, 95% confidence interval [CI] 1.05-1.55, p = 0.02), trunk fat mass (OR 1.13, 95% CI 1.03-1.24, p = 0.01), and android fat mass (OR 1.77, 95% CI 1.16-2.82, p = 0.01) were independent risk factors for GLS < 18%.

CONCLUSION

Among patients with type 2 diabetes mellitus without established clinical cardiac disease, fat mass, especially android fat mass, was associated with subclinical systolic dysfunction independently of age and sex.