Cardiac Imaging for the Assessment of Left Atrial Mechanics Across Heart Failure Stages

Estimate of the hydraulic force in the aging heart: a cardiovascular magnetic resonance imaging study

BACKGROUND

Coupling between left ventricle (LV) and left atrium (LA) plays a central role in the process of cardiac remodeling during aging and development of cardiac disease. The hydraulic force (HyF) is related to variation in size between LV and LA. The objectives of this study were to: (1) derive an estimate of left atrioventricular HyF using cine- Magnetic Resonance Imaging (MRI) in healthy subjects with a wide age range, and (2) study its relationship with age and conventional diastolic function parameters, as estimated by reference echocardiography.

METHODS

We studied 119 healthy volunteers (mean age 44 ± 17 years, 58 women) who underwent Doppler echocardiography and MRI on the same day. Conventional transmitral flow early (E) and late (A) LV filling peak velocities as well as mitral annulus diastolic longitudinal peak velocity (E') were derived from echocardiography. MRI cine SSFP images in longitudinal two and four chamber views were acquired, and analyzed using feature tracking (FT) software. In addition to conventional LV and LA strain measurements, FT-derived LV and LA contours were further used to calculate chamber cross-sectional areas. HyF was approximated as the difference between the LV and LA maximal cross-sectional areas in the diastasis phase corresponding to the lowest LV-LA pressure gradient. Univariate and multivariate analyses while adjusting for appropriate variables were used to study the associations between HyF and age as well as diastolic function and strain indices.

RESULTS

HyF decreased significantly with age (R²=0.34, p < 0.0001). In addition, HyF was significantly associated with conventional indices of diastolic function and LA strain: E/A: R²=0.24, p < 0.0001; E': R²=0.24, p < 0.0001; E/E': R²=0.12, p = 0.0004; LA conduit longitudinal strain: R²=0.27, p < 0.0001. In multivariate analysis, associations with E/A (R2 = 0.39, p = 0.03) and LA conduit strain (R2 = 0.37, p = 0.02) remained significant after adjustment for age, sex, and body mass index.

CONCLUSIONS

HyF, estimated using FT contours, which are primarily used to quantify LV/LA strain on standard cardiac cine MRI, varied significantly with age in association with subclinical changes in ventricular filling. Its usefulness in cohorts of patients with left heart disease to detect LV-LA uncoupling remains to be evaluated.

The epileptic heart: Cardiac comorbidities and complications of epilepsy. Atrial and ventricular structure and function by echocardiography in individuals with epilepsy - From clinical implications to individualized assessment

Epilepsy is an increasing global neurological health issue. Recently, epidemiological and mechanistic studies have raised concern about cardiac involvement in individuals with epilepsy. This has resulted in the "epileptic heart" concept. Epidemiological data linking epilepsy to cardiovascular disease indicate an increased risk for ventricular and atrial arrhythmias, myocardial infarction, heart failure, and sudden death among individuals with epilepsy. Pathways of this interaction comprise increased prevalence of traditional cardiac risk factors, genetic abnormalities, altered brain circuitry with autonomic imbalance, and antiseizure medications with enzyme-inducing and ionic channel-blocking proprieties. Pathophysiological findings in the atria and ventricles of patients with epilepsy are discussed. Echocardiographic findings and future applications of this tool are reviewed. A risk stratification model and future studies on cardiac risk assessment in individuals with epilepsy are proposed.

A systematic review and meta-analysis of left atrial strain in hypertrophic cardiomyopathy and its prognostic utility

Despite advances in noninvasive imaging modalities to identify atrial fibrillation (AF) risk in Hypertrophic Cardiomyopathy (HCM), there is a paucity of evidence concerning the impact of low Left Atrial strain (LAS) on AF and major adverse cardiac events (MACE) incidence in these patients. This study investigated the diagnostic and prognostic significance of LAS in predicting AF and MACE in HCM. Findings revealed lower LA reservoir (MD: -11.79, 95% CI -14.83, -8.74; p<0.00001), booster (MD: -4.10, 95% CI -6.29, -1.91; p=0.0002), and conduit (MD: -7.52, 95% CI -9.39, -5.65; p<0.00001) strains in HCM patients versus healthy controls, and also indicated a significant association between low LA reservoir/conduit/booster strain and the development of new AF as well as MACE prevalence in HCM patients. The results from this study suggest the valuable role of LA strain in HCM and its utility in predicting the development of new AF and cardiac events in HCM patients.

Early predicting improvement of severe systolic heart failure by left atrial volume

Left atrium (LA) modulates left ventricle (LV) filling and cardiac performance. We aimed to assess the effect of heart failure (HF) therapy on LA and LV function, and the relationship between LA/LV improvement and clinical outcome in acute HF with reduced LV ejection fraction (LVEF). Totally, 224 hospitalized patients with acute HF and LVEF < 35% were enrolled and underwent echocardiography. They all received maximal tolerable doses of evidence-based medications. Patients received echocardiographic measurements at each visit including stroke volume, LVEF, LA minimal/maximal volume (LAV_min/LAV_max), LA expansion index, and tissue Doppler parameters. The threshold of LV functional improvement was LVEF > 45% ever occurred before study end. During the mean follow-up of 6.3 years, 62 cases improved well, mean LVEF 49 ± 5% at study end. The reduction of LV filling pressure occurring as early as 2 weeks later, LV systolic function improvement took longer (> 1 month). The reductions in LAV_min and LAV_max between initial stabilization and 2 weeks after HF treatment (Initial-2 W) and the increase of LA expansion index (Initial-2 W) were associated independently with LVEF improvement (p 0.002, 0.006, and 0.007, respectively). The best predictor of LVEF improvement was LAV_min reduction (Initial-2 W) > 5 ml with 77% sensitivity, 76% specificity. Cox proportional hazard regression analyses for cardiovascular events revealed LVEF improvement reduced 74% of events (hazard ratio 0.264, 95% CI 0.192-0.607, p < 0.0001); and LA expansion index (per 1% increase) reduced 14% of events (hazard ratio 0.862, 95% CI 0.771-0.959, p < 0.0001). The early reduction of LAV (Initial-2 W), especially LAV_min, is a powerful early predictor of LVEF improvement. Its occurrence reduces cardiovascular events significantly. ClinicalTrials.gov number: NCT01307722.

Incremental prognostic value of left atrial strain in patients with heart failure

AIMS

The present study aimed to evaluate the prognostic value of atrial strain and strain rate (SR) parameters derived from cardiac magnetic resonance (CMR) feature tracking (FT) in patients with ischaemic and non-ischaemic dilated cardiomyopathy with heart failure with reduced ejection fraction (HFrEF) but without atrial fibrillation.

METHODS AND RESULTS

A total of 300 patients who underwent CMR with left ventricular ejection fraction (LVEF) ≤ 40% and ischaemic or non-ischaemic dilated cardiomyopathy were analysed in this retrospective study. Major adverse cardiac events (MACEs) include cardiovascular death, heart transplantation, and rehospitalization for worsening HF. Ninety-four patients had MACEs during median follow-up of 3.84 years. Multivariate Cox regression models adjusted for common clinical and CMR risk factors detected a significant association between LA-εs and MACE in ischaemic (HR = 0.94/%; P = 0.002), non-ischaemic dilated cardiomyopathy (HR = 0.88/%; P = 0.001), or all included patients (HR = 0.87; P < 0.001). LA-εs provided incremental prognostic value over conventional outcome predictors (Uno C statistical comparison model: from 0.776 to 0.801, P < 0.0001; net reclassification improvement: 0.075, 95% CI: 0.0262-0.1301). Kaplan-Meier analysis revealed that the risk of MACE occurrence increased significantly with lower tertiles of left atrial reservoir strain (LA-εs) (log-rank P < 0.0001). Patients in the worst LA-εs tertile faced a significantly increased risk of MACEs irrespective of late gadolinium enhancement (LGE) (log-rank P < 0.0001).

CONCLUSIONS

LA-εs derived from CMR FT has a significant prognostic impact on patients with ischaemic or non-ischaemic dilated cardiomyopathy, incremental to common clinical and CMR risk-factors.

Left atrial strain determinants and clinical features according to the heart failure stages. New insight from EACVI MASCOT registry

Few studies analyzed left atrial (LA) peak atrial longitudinal strain (PALS) determinants, particularly across heart failure (HF) stages. We aimed to analyze the pathophysiological and clinical PALS correlates in a large multicentric prospective study. This is a multicenter prospective observational study enrolling 745 patients with HF stages. Data included PALS and left ventricular global longitudinal strain (LV-GLS). Exclusion criteria were: valvular prosthesis; atrial fibrillation; cardiac transplantation; poor acoustic window. Median global PALS was 17% [24–32]. 29% of patients were in HF-stage 0/A, 35% in stage-B, and 36% in stage-C. Together with age, the echocardiographic determinants of PALS were LA volume and LV-GLS (overall model R2 = 0.50, p < 0.0001). LV-GLS had the strongest association with PALS at multivariable analysis (beta: −3.60 ± 0.20, p < 0.0001). Among HF stages, LV-GLS remained the most important PALS predictor (p < 0.0001) whereas age was only associated with PALS in lower HF-stage 0/A or B (R = − 0.26 p < 0.0001, R = − 0.23 p = 0.0001). LA volume increased its association to PALS moving from stage 0/A (R = − 0.11; P = 0.1) to C (R = − 0.42; P < 0.0001). PALS was the single most potent echocardiographic parameter in predicting the HF stage (AUC for B vs. 0/A 0.81, and AUC vs. 0/A for C 0.76). PALS remained independently associated with HF stages after adjusting for ejection fraction, E/e′ ratio, and mitral regurgitation grade (p < 0.0001). Although influenced by LV-GLS and LA size across HF stages, PALS is incrementally and independently associated with clinical status. LA function may reflect a substantial part of the hemodynamic consequences of ventricular dysfunction.

Prognostic Value of Left Atrial Strain in Heart Failure: A Systematic Review and Meta-Analysis

Background

Heart failure (HF) is a global health problem with high morbidity and mortality. Recently, the association between peak atrial longitudinal strain (PALS) and clinical outcomes of HF has gained increasing attention. Our aim was to systematically assess the prognostic value of PALS for adverse events in HF.

Methods

PubMed, Embase, and Scopus databases were systematically searched from inception to 30 April 2022. Studies in which PALS was assessed to predict adverse outcomes in adult patients with HF were included. Study selection, quality assessment, and data extraction were performed independently by two authors. The primary endpoints were all-cause death and cardiac hospitalization.

Results

Among 7,787 patients in 17 included studies, 3,029 (38.9%) experienced the primary endpoint. Patients with events had lower PALS than those without events [weighted mean difference (WMD) 6.17, 95% confidence interval (CI) 3.09–9.26, p < 0.001]. Each unit increment of PALS was independently associated with decreased risk for the primary endpoint [hazard ratio (HR) 0.96, 95% CI 0.94–0.98, p < 0.001]. The addition of PALS significantly improved the predictive power of conventional risk models [net reclassification index (NRI) 0.22, 95% CI 0.06–0.39, p = 0.008].

Conclusion

Peak atrial longitudinal strain was an independent predictor for all-cause mortality and cardiac hospitalization in patients with HF, highlighting the clinical importance of left atrial (LA) deformation in the prognosis of HF.

Systematic Review Registration

[www.crd.york.ac.uk/prospero/], identifier [CRD42020185034].

Molecular Changes in Prepubertal Left Ventricular Development Under Experimental Volume Overload

Background

Left ventricular (LV) volume overload (VO), commonly found in patients with chronic aortic regurgitation (AR), leads to a series of left ventricular (LV) pathological responses and eventually irreversible LV dysfunction. Recently, questions about the applicability of the guideline for the optimal timing of valvular surgery to correct chronic AR have been raised in regard to both adult and pediatric patients. Understanding how VO regulates postnatal LV development may shed light on the best timing of surgical or drug intervention.

Methods and Results

Prepubertal LV VO was induced by aortocaval fistula (ACF) on postnatal day 7 (P7) in mice. LV free walls were analyzed on P14 and P21. RNA-sequencing analysis demonstrated that normal (P21_Sham vs.P14_Sham) and VO-influenced (P21_VO vs. P14_VO) LV development shared common terms of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) in the downregulation of cell cycle activities and the upregulation of metabolic and sarcomere maturation. The enriched GO terms associated with cardiac condition were only observed in normal LV development, while the enriched GO terms associated with immune responses were only observed in VO-influenced LV development. These results were further validated by the examination of the markers of cell cycle, maturation, and immune responses. When normal and VO-influenced LVs of P21 were compared, they were different in terms of immune responses, angiogenesis, percentage of Ki67-positive cardiomyocytes, mitochondria number, T-tubule regularity, and sarcomere regularity and length.

Conclusions

A prepubertal LV VO mouse model was first established. VO has an important influence on LV maturation and development, especially in cardiac conduction, suggesting the requirement of an early correction of AR in pediatric patients. The underlying mechanism may be associated with the activation of immune responses.