Left Atrial Strain in the Assessment of Diastolic Function in Heart Failure: A Machine Learning Approach

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.

Prognostic significance and clinical utility of left atrial reservoir strain in transcatheter aortic valve replacement

AIMS

Patients with diastolic dysfunction (DD) experience worse outcomes after transcatheter aortic valve replacement (TAVR). We investigated the prognostic value and clinical utility of left atrial reservoir strain (LARS) in patients undergoing TAVR for aortic stenosis (AS).

METHODS AND RESULTS

All consecutive patients undergoing TAVR between January 2018 and December 2018 were included if discharge echocardiography and follow-up were available. LARS was derived from 2D-speckle-tracking. Patients were grouped into three tertiles according to LARS. DD was analysed using the ASE/EACVI-algorithm. The primary outcome was a composite of all-cause death and readmission for worsening heart failure 12 months after TAVR. Overall, 606 patients were available [age 80 years, interquartile range (IQR) 77-84], including 53% women. Median LARS was 13.0% (IQR 8.4-18.3). Patients were classified by LARS tertiles [mildly impaired 21.4% (IQR 18.3-24.5), moderately impaired 13.0% (IQR 11.3-14.6), severely impaired 7.1% (IQR 5.4-8.4), P < 0.0001]. The primary outcome occurred more often in patients with impaired LARS (mildly impaired 7.4%, moderately impaired 13.4%, and severely impaired 25.7%, P < 0.0001). On adjusted multivariable Cox regression analysis, LARS tertiles [hazard ratio (HR) 0.62, 95% confidence interval (CI) 0.44-0.86, P = 0.005] and higher degree of tricuspid regurgitation (HR 1.82, 95% CI 1.23-2.98, P = 0.003) were the only significant predictors of the primary endpoint. Importantly, DD was unavailable in 56% of patients, but LARS assessment allowed for reliable prognostication regarding the primary endpoint in subgroups without DD assessment (HR 0.64, 95% CI 0.47-0.87, P = 0.003).

CONCLUSION

Impaired LARS is independently associated with worse outcomes in patients undergoing TAVR. LARS allows for risk stratification at discharge even in patients where DD cannot be assessed by conventional echocardiographic means.

Diastology in the intensive care unit: Challenges for the assessment and future directions

Myocardial dysfunction is common in patients admitted to the intensive care unit (ICU). Septic disease frequently results in cardiac dysfunction, and sepsis represents the most common cause of admission and death in the ICU. The association between left ventricular (LV) systolic dysfunction and mortality is not clear for critically ill patients. Conversely, LV diastolic dysfunction (DD) seems increasingly recognized as a factor associated with poor outcomes, not only in sepsis but also more generally in critically ill patients. Despite recent attempts to simplify the diagnosis and grading of DD, this remains relatively complex, with the need to use several echocardiographic parameters. Furthermore, the current guidelines have several intrinsic limitations when applied to the ICU setting. In this manuscript, we discuss the challenges in DD classification when applied to critically ill patients, the importance of left atrial pressure estimates for the management of patients in ICU, and whether the study of cardiac dysfunction spectrum during critical illness may benefit from the integration of left ventricular and left atrial strain data to improve diagnostic accuracy and implications for the treatment and prognosis.

Normal Values and Reference Ranges for the Ratio of Transmitral Early Filling Velocity to Early Diastolic Strain Rate: The Copenhagen City Heart Study

BACKGROUND

The ratio of transmitral early filling velocity to early diastolic strain rate (E/e'sr) has recently emerged as a measure of left ventricular filling pressure. Reference values are needed for this new parameter for it to be used clinically.

METHODS

Healthy participants from a prospective general population study, the Fifth Copenhagen City Heart Study, were assessed to establish reference values for E/e'sr derived from two-dimensional speckle-tracking echocardiography. The prevalence of abnormal E/e'sr was assessed in participants with cardiovascular risk factors or specific diseases.

RESULTS

The population comprised 1,623 healthy participants (median age, 45; interquartile range, 32-56; 61% female). The upper reference limit for E/e'sr in the population was 79.6 cm. Following multivariable adjustment, male participants exhibited significantly higher E/e'sr than female participants (upper reference limit for male participants, 83.7 cm; for female participants, 76.5 cm). For both sexes, E/e'sr increased in a curvilinear fashion with age such that the largest increases in E/e'sr were observed in participants >45 years. In the entire CCHS5 population with E/e'sr available (n = 3,902), increasing age, body mass index, systolic blood pressure, male sex, estimated glomerular filtration rate, and diabetes were associated with E/e'sr (all P < .05). Total cholesterol was associated with a less steep increase in E/e'sr. Abnormal E/e'sr was seldomly observed in participants with normal diastolic function but became more frequent in participants with increasing grades of diastolic dysfunction (normal, mild, moderate, severe [abnormal E/e'sr for each grade: 4.4% vs 20.0% vs 16.2% vs 55.6%, respectively]).

CONCLUSION

The E/e'sr differs between sexes and is age dependent such that E/e'sr increases with advancing age. Therefore, we established sex- and age-stratified reference values for E/e'sr.

Personalized biomechanical insights in atrial fibrillation: opportunities & challenges

INTRODUCTION

Atrial fibrillation (AF) is an increasingly prevalent and significant worldwide health problem. Manifested as an irregular atrial electrophysiological activation, it is associated with many serious health complications. AF affects the biomechanical function of the heart as contraction follows the electrical activation, subsequently leading to reduced blood flow. The underlying mechanisms behind AF are not fully understood, but it is known that AF is highly correlated with the presence of atrial fibrosis, and with a manifold increase in risk of stroke.

AREAS COVERED

In this review, we focus on biomechanical aspects in atrial fibrillation, current and emerging use of clinical images, and personalized computational models. We also discuss how these can be used to provide patient-specific care.

EXPERT OPINION

Understanding the connection betweenatrial fibrillation and atrial remodeling might lead to valuable understanding of stroke and heart failure pathophysiology. Established and emerging imaging modalities can bring us closer to this understanding, especially with continued advancements in processing accuracy, reproducibility, and clinical relevance of the associated technologies. Computational models of cardiac electromechanics can be used to glean additional insights on the roles of AF and remodeling in heart function.

The Improvement of Left Atrial Function after Twelve Weeks of Supervised Concurrent Training in Patients with Heart Failure with Mid-Range Ejection Fraction: A Pilot Study

Left atrial dysfunction is associated with exercise intolerance and poor prognosis in heart failure (HF). The effects of exercise training on atrial function in patients with HF with mid-range ejection fraction (HFmrEF) are unknown. The purpose of the present study was to assess the effects of a supervised concurrent training (SCT) program, lasting 12 weeks, on left atrial function of patients with HFmrEF. The study included 70 stable patients, who were randomly assigned into two groups: SCT with (three sessions/week) or a control (CON) group directed to follow contemporary exercise preventive guidelines at home. Before starting the training program and at 12 weeks, all patients performed an ergometric test, a 6 min walk test, and echocardiography. Between-group comparisons were made by analysis of variance (ANOVA). At 12 weeks, the duration of the ergometric test and distance walked at 6 min walk test presented a significant greater increase in SCT compared to the control (between-group p 0.0001 and p 0.004 respectively). Peak atrial longitudinal strain and conduit strain presented an increase of 29% and 34%, respectively, in the SCT, and were unchanged in CON (between-group p 0.008 and p 0.001, respectively). Peak atrial contraction strain increased by 21% in SCT, with no changes in CON (between-group p 0.002). Left ventricular global longitudinal strain increased significantly in SCT compared to control (between-groups p 0.03). In conclusions, SCT improved left atrial and left ventricular function in HFmrEF. Further studies are needed in order to verify whether these favourable effects of SCT on LA function are sustained and whether they will translate into clinical benefits for patients with HFmrEF.