Right atrial volume by cardiovascular magnetic resonance predicts mortality in patients with heart failure with reduced ejection fraction

Right Atrial Phasic Function in Heart Failure with Preserved Ejection Fraction: Cardiac Magnetic Resonance Feature Tracking and Outcomes

BACKGROUND

This study sought to investigate the prognostic impact of right atrial (RA) size and function in patients with heart failure with preserved ejection fraction (HFpEF) in sinus rhythm (SR) and atrial fibrillation (AF).

METHODS

Consecutive HFpEF patients were enrolled and indexed RA volumes and emptying fractions (RA-EF) were assessed by cardiac magnetic resonance imaging (CMR). For patients in SR, feature tracking of the RA wall was performed during CMR. In addition, all patients underwent right and left heart catheterization and 6 min walk distance (6MWD) and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) evaluations. We prospectively followed patients and used Cox regression models to determine the association of RA size and function with a composite endpoint of heart failure hospitalization and cardiovascular death.

RESULTS

A total of 188 patients (71% female patients, 70 ± 8 years old) were included. Ninety-two patients (49%) were in persistent AF. Eighty-five patients reached the combined endpoint during a follow-up of 69 (42-97) months. After a multivariate cox regression analysis, the impaired RA reservoir strain (HR 0.949; 95% CI [0.909-0.990], p = 0.016), the RA reservoir strain rate (HR 0.991; 95% CI [0.983-0.999], p = 0.028), the RA conduit strain (HR 0.932; 95% CI [0.879-0.988], p = 0.019), and the RA conduit strain rate (HR 0.989; 95% CI [0.881-0.997], p = 0.011) were significantly associated with a worse outcome for patients in SR. In persistent AF, no RA imaging parameter was related to outcome after a multivariate regression analysis.

CONCLUSIONS

In HFpEF patients in SR, CMR parameters of impaired RA conduit and reservoir function are associated with dismal cardiovascular outcomes. In persistent AF, RA parameters lose their prognostic ability.

Development and validation of echocardiography-based machine-learning models to predict mortality

BACKGROUND

Echocardiography (echo) based machine learning (ML) models may be useful in identifying patients at high-risk of all-cause mortality.

METHODS

We developed ML models (ResNet deep learning using echo videos and CatBoost gradient boosting using echo measurements) to predict 1-year, 3-year, and 5-year mortality. Models were trained on the Mackay dataset, Taiwan (6083 echos, 3626 patients) and validated in the Alberta HEART dataset, Canada (997 echos, 595 patients). We examined the performance of the models overall, and in subgroups (healthy controls, at risk of heart failure (HF), HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF)). We compared the models' performance to the MAGGIC risk score, and examined the correlation between the models' predicted probability of death and baseline quality of life as measured by the Kansas City Cardiomyopathy Questionnaire (KCCQ).

FINDINGS

Mortality rates at 1-, 3- and 5-years were 14.9%, 28.6%, and 42.5% in the Mackay cohort, and 3.0%, 10.3%, and 18.7%, in the Alberta HEART cohort. The ResNet and CatBoost models achieved area under the receiver-operating curve (AUROC) between 85% and 92% in internal validation. In external validation, the AUROCs for the ResNet (82%, 82%, and 78%) were significantly better than CatBoost (78%, 73%, and 75%), for 1-, 3- and 5-year mortality prediction respectively, with better or comparable performance to the MAGGIC score. ResNet models predicted higher probability of death in the HFpEF and HFrEF (30%-50%) subgroups than in controls and at risk patients (5%-20%). The predicted probabilities of death correlated with KCCQ scores (all p < 0.05).

INTERPRETATION

Echo-based ML models to predict mortality had good internal and external validity, were generalizable, correlated with patients' quality of life, and are comparable to an established HF risk score. These models can be leveraged for automated risk stratification at point-of-care.

FUNDING

Funding for Alberta HEART was provided by an Alberta Innovates - Health Solutions Interdisciplinary Team Grant no. AHFMRITG 200801018. P.K. holds a Canadian Institutes of Health Research (CIHR) Sex and Gender Science Chair and a Heart & Stroke Foundation Chair in Cardiovascular Research. A.V. and V.S. received funding from the Mitacs Globalink Research Internship.

The prognostic value of right ventricular ejection fraction by cardiovascular magnetic resonance in heart failure: A systematic review and meta-analysis

BACKGROUND

Cardiac magnetic resonance (CMR) is considered the gold standard for the assessment of right ventricular ejection fraction (RVEF). Previous studies have suggested that RVEF may be a predictor of adverse outcomes in heart failure (HF). In this study, we aimed to systematically review the prognostic value of RVEF, evaluated by CMR, across the spectrum of left ventricular systolic function in patients with HF.

METHODS

Electronic databases were searched for studies investigating the prognostic value of RVEF in HF, irrespective of left ventricular ejection fraction (LVEF). A random-effects meta-analysis was conducted for mortality and HF hospitalization. Subgroup analyses were also performed based on the presence of reduced (<50%) or preserved LVEF (≥50%).

RESULTS

In total, 46 studies enrolling 14,344 patients were included. In the pooled analyses, impaired RVEF was a powerful predictor of mortality (HR: 1.26, 95% CI: 1.18-1.33, I²: 13%, per 10% decrease in RVEF) and death or HF hospitalization (HR: 1.31, 95% Cl: 1.2-1.42, I²: 27%, per 10% decrease in RVEF). A decrease in RVEF was strongly associated with increased risk of mortality or hospitalization both in HF with reduced EF (HR: 1.24, 95% CI: 1.13-1.36, I²: 2%, per 10% decrease in RVEF) and in HF with preserved EF (HR: 1.24, 95% CI: 1.09-1.40, I²: 0%, per 10% decrease in RVEF).

CONCLUSION

Impaired RVEF on CMR strongly predicts adverse outcomes in patients with HF regardless of LVEF. RV systolic function should be carefully evaluated in these patients. Prospero Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021256967.

Training and clinical testing of artificial intelligence derived right atrial cardiovascular magnetic resonance measurements

BACKGROUND

Right atrial (RA) area predicts mortality in patients with pulmonary hypertension, and is recommended by the European Society of Cardiology/European Respiratory Society pulmonary hypertension guidelines. The advent of deep learning may allow more reliable measurement of RA areas to improve clinical assessments. The aim of this study was to automate cardiovascular magnetic resonance (CMR) RA area measurements and evaluate the clinical utility by assessing repeatability, correlation with invasive haemodynamics and prognostic value.

METHODS

A deep learning RA area CMR contouring model was trained in a multicentre cohort of 365 patients with pulmonary hypertension, left ventricular pathology and healthy subjects. Inter-study repeatability (intraclass correlation coefficient (ICC)) and agreement of contours (DICE similarity coefficient (DSC)) were assessed in a prospective cohort (n = 36). Clinical testing and mortality prediction was performed in n = 400 patients that were not used in the training nor prospective cohort, and the correlation of automatic and manual RA measurements with invasive haemodynamics assessed in n = 212/400. Radiologist quality control (QC) was performed in the ASPIRE registry, n = 3795 patients. The primary QC observer evaluated all the segmentations and recorded them as satisfactory, suboptimal or failure. A second QC observer analysed a random subcohort to assess QC agreement (n = 1018).

RESULTS

All deep learning RA measurements showed higher interstudy repeatability (ICC 0.91 to 0.95) compared to manual RA measurements (1st observer ICC 0.82 to 0.88, 2nd observer ICC 0.88 to 0.91). DSC showed high agreement comparing automatic artificial intelligence and manual CMR readers. Maximal RA area mean and standard deviation (SD) DSC metric for observer 1 vs observer 2, automatic measurements vs observer 1 and automatic measurements vs observer 2 is 92.4 ± 3.5 cm2, 91.2 ± 4.5 cm2 and 93.2 ± 3.2 cm2, respectively. Minimal RA area mean and SD DSC metric for observer 1 vs observer 2, automatic measurements vs observer 1 and automatic measurements vs observer 2 was 89.8 ± 3.9 cm2, 87.0 ± 5.8 cm2 and 91.8 ± 4.8 cm2. Automatic RA area measurements all showed moderate correlation with invasive parameters (r = 0.45 to 0.66), manual (r = 0.36 to 0.57). Maximal RA area could accurately predict elevated mean RA pressure low and high-risk thresholds (area under the receiver operating characteristic curve artificial intelligence = 0.82/0.87 vs manual = 0.78/0.83), and predicted mortality similar to manual measurements, both p < 0.01. In the QC evaluation, artificial intelligence segmentations were suboptimal at 108/3795 and a low failure rate of 16/3795. In a subcohort (n = 1018), agreement by two QC observers was excellent, kappa 0.84.

CONCLUSION

Automatic artificial intelligence CMR derived RA size and function are accurate, have excellent repeatability, moderate associations with invasive haemodynamics and predict mortality.

Fibrillation cycle length predicts cardiovascular events in patients with long-standing persistent atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is associated with an increased risk of heart failure (HF), stroke, and death. Although fibrillation cycle length (FCL) is used as a surrogate for atrial refractoriness, its impact on outcomes remains unclear. This study aimed to identify predictors of cardiovascular events, including FCL, in patients with long-standing persistent AF.

METHODS

The study included 190 consecutive patients with long-standing persistent AF (mean age 74 years, 74% male). Patients with valvular AF or hemodialysis-dependent end-stage renal disease and those on anti-arrhythmic drugs were excluded. The primary composite outcome was occurrence of cardiovascular events (myocardial infarction, HF), cerebrovascular events (stroke, transient ischemic attack), and all-cause death. FCL was calculated by fast Fourier transformation analysis of fibrillation waves in the surface electrocardiogram.

RESULTS

Over a median follow-up of 2.6 years, the primary outcome occurred in 31 patients (cardiovascular events, n = 18; cerebrovascular events, n = 8; all-cause death, n = 5). In multivariate analysis, longer FCL and history of HF were independent predictors of these outcomes. In a Cox proportional hazards model adjusted for age, sex, and history of HF, patients with an FCL > 160 ms (cut-off determined by receiver-operating characteristic curve analysis) were at increased risk of the outcome (hazard ratio 12.9; 95% confidence interval 4.99-44.10; p < 0.001).

CONCLUSIONS

FCL was independently associated with cardiovascular outcomes in patients with long-standing persistent AF.

Impaired Relaxation and Reduced Lusitropic Reserve in Atrial Myocardium in the Obese Patients

Background: Obesity can influence the structure and function of the atrium, but most studies focused on the relationship of body mass index (BMI) and overt left atrium (LA) dysfunction as assessed by clinical imaging. We combined the assessment of right atrium (RA) function in vivo and in vitro in obese and non-obese patients scheduled for elective cardiac surgery.

Methods: Atrial structure and function were quantified pre-operatively by echocardiography. RA tissue removed for the establishment of extracorporeal support was collected and RA trabeculae function was quantified in vitro at baseline and with adrenergic stimulation (isoproterenol). Fatty acid-binding protein 3 (FABP3) was quantified in RA tissue. Results were stratified according to the BMI of the patients.

Results: About 76 patients were included pre-operatively for the echocardiographic analysis. RA trabeculae function at baseline was finally quantified from 46 patients and RA function in 28 patients was also assessed with isoproterenol. There was no significant correlation between BMI and the parameters of atrial function measured by the clinical echocardiography. However, in vitro measurements revealed a significant correlation between BMI and a prolonged relaxation of the atrial myocardium at baseline, which persisted after controlling for the atrial fibrillation and diabetes by the partial correlation analysis. Acceleration of relaxation with isoproterenol was significantly lower in the obese group (BMI ≥ 30 kg/m²). As a result, relaxation with adrenergic stimulation in the obese group remained significantly higher compared to the overweight group (25 kg/m² ≤ BMI < 30 kg/m², p = 0.027) and normal group (18.5 kg/m² ≤ BMI < 25 kg/m², p = 0.036). There were no differences on impacts of the isoproterenol on (systolic) developed force between groups. The expression of FABP3 in the obese group was significantly higher compared to the normal group (p = 0.049) and the correlation analysis showed the significant correlations between the level of FABP3 in the RA trabeculae function.

Conclusion: A higher BMI is associated with the early subclinical changes of RA myocardial function with the slowed relaxation and reduced adrenergic lusitropy.

Right Heart Pulmonary Circulation Unit Involvement in Left-Sided Heart Failure: Diagnostic, Prognostic, and Therapeutic Implications

Although long neglected, the right heart (RH) is now widely accepted as a pivotal player in heart failure (HF) either with reduced or preserved ejection fraction. The chronic overload of the pulmonary microcirculation results in an initial phase characterized by right ventricular (RV) hypertrophy, right atrial dilation, and diastolic dysfunction. This progresses to overt RH failure when RV dilation and systolic dysfunction lead to RV-pulmonary arterial (RV-PA) uncoupling with low RV output. In the context of its established relevance to progression of HF, clinicians should consider assessment of the RH with information from clinical assessment, biomarkers, and imaging. Notably, no single parameter can predict prognosis alone in HF. Assessments simultaneously should encompass RV systolic function, pulmonary pressures, an estimation of RV-PA coupling, and RH morphologic features. Despite a large volume of evidence indicating the relevance of RH function to the clinical syndrome of HF, evidence-based management strategies are lacking. Targeting RH dysfunction in HF should be an objective of future investigations, being an unmet need in the current management of HF.

Right Atrial Volume Index as a Predictor of Persistent Right Ventricular Dysfunction in Patients with Acute Inferior Myocardial Infarction and Proximal Right Coronary Artery Occlusion Treated with Primary Percutaneous Coronary Intervention

Objectives

Patients with right ventricular (RV) infarctions associated with inferior infarctions have higher rates of adverse events than isolated inferior infarctions. Right atrial volume index (RAVI) has recently been described as a predictor of clinical outcome in patients with chronic systolic heart failure and pulmonary hypertension. The aim of this study is to assess the ability of RAVI to predict the persistent RV dysfunction after acute inferior STEMI due to occlusion of proximal RCA. To the best of our knowledge, this is the first study to investigate the relation between RAVI and persistent RV dysfunction in such group of patients.

Patients and methods

Sixty-five consecutive patients with recent first acute inferior STEMI who underwent primary percutaneous coronary intervention (PPCI) were prospectively included in the study. Echocardiographic evaluation was performed at the time of discharge and at 3 months. All the patients underwent standard echocardiographic assessment using conventional 2D and tissue Doppler imaging (TDI).

Results

Patients were divided into two groups according to right ventricular function (RVF) 3 months after acute myocardial infarction (AMI). The normal RVF group included 41 (63%) patients and the impaired RVF group included 24 (37%) patients. RAVI was significantly higher in patients with impaired RVF (p=<0.001). RAVI was a predictor of persistently impaired RV function (odds ratio = 1.786, 95% confidence interval, 1.367–2.335, p value= <0.001) and (odds ratio = 1.829, 95% confidence interval, 1.358–2.462, p value= <0.001) in univariate and multivariable logistic regression analyses respectively. In receiving operator characteristics (ROC) curve analysis, RAVI with a cutoff value ≥ 30 ml/m² had a 87.5% sensitivity, a 92.24% specificity area under Receiving operator characteristics (ROC) curve = 0.964 for predicting persistently impaired RVF.

Conclusion

In patients with inferior STEMI with proximal RCA occlusion, RAVI is an independent predictor of persistently impaired RVF with a cut-off value ≥ 30 ml/m².

Impact of Right Atrial Remodeling in Heart Failure With Preserved Ejection Fraction

BACKGROUND

Few studies have investigated right atrial (RA) remodeling in heart failure (HF) with preserved ejection fraction (HFpEF). This study sought to characterize the RA remodeling in HFpEF and to determine its prognostic significance.

METHODS AND RESULTS

Patients with HFpEF were classified based on the presence of RA enlargement (RA volume index >39 mL/m² in men and >33 mL/m² in women). Compared with patients with normal RA size (n = 234), patients with RA dilation (n = 67) showed a higher prevalence of atrial fibrillation (AF), worse right ventricular systolic function, more severe pulmonary hypertension, and a greater prevalence of mild tricuspid regurgitation, as well as impaired RA reservoir function, with increased hepatobiliary enzyme levels. AF was strongly associated with the presence of RA dilation (odds ratio [OR] 10.2, 95% confidence interval [CI] 4.00-26.1 in current AF vs no AF and odds ratio 3.38, 95% CI 1.26-9.07, earlier AF vs no AF). Patients with RA dilation had more than a two-fold increased risk of composite outcomes of all-cause mortality or HF hospitalization (adjusted hazard ratio 2.01, 95% CI 1.09-3.70, P = .02). The presence of RA dilation also displayed an additive prognostic value over left atrial dilation alone.

CONCLUSIONS

These data demonstrate that HFpEF with RA remodeling is associated with distinct echocardiographic features characterizing advanced right heart dysfunction with an increased risk of adverse outcomes.

A publicly available virtual cohort of four-chamber heart meshes for cardiac electro-mechanics simulations

Computational models of the heart are increasingly being used in the development of devices, patient diagnosis and therapy guidance. While software techniques have been developed for simulating single hearts, there remain significant challenges in simulating cohorts of virtual hearts from multiple patients. To facilitate the development of new simulation and model analysis techniques by groups without direct access to medical data, image analysis techniques and meshing tools, we have created the first publicly available virtual cohort of twenty-four four-chamber hearts. Our cohort was built from heart failure patients, age 67±14 years. We segmented four-chamber heart geometries from end-diastolic (ED) CT images and generated linear tetrahedral meshes with an average edge length of 1.1±0.2mm. Ventricular fibres were added in the ventricles with a rule-based method with an orientation of -60° and 80° at the epicardium and endocardium, respectively. We additionally refined the meshes to an average edge length of 0.39±0.10mm to show that all given meshes can be resampled to achieve an arbitrary desired resolution. We ran simulations for ventricular electrical activation and free mechanical contraction on all 1.1mm-resolution meshes to ensure that our meshes are suitable for electro-mechanical simulations. Simulations for electrical activation resulted in a total activation time of 149±16ms. Free mechanical contractions gave an average left ventricular (LV) and right ventricular (RV) ejection fraction (EF) of 35±1% and 30±2%, respectively, and a LV and RV stroke volume (SV) of 95±28mL and 65±11mL, respectively. By making the cohort publicly available, we hope to facilitate large cohort computational studies and to promote the development of cardiac computational electro-mechanics for clinical applications.

Right Atrial Phasic Function in Heart Failure With Preserved and Reduced Ejection Fraction

OBJECTIVES

This study researched right atrial (RA) deformation indexes and their association with all-cause mortality among subjects with or without heart failure (HF).

BACKGROUND

Although left atrial dysfunction is well described in HF, patterns of RA dysfunction and their prognostic implications are unclear. Cardiac magnetic resonance (CMR) imaging can provide excellent visualization of the RA. We used CMR to characterize RA phasic function in HF and to assess its prognostic implications.

METHODS

This study prospectively examined 608 adults without HF (n = 407), as well as adults with HF with a reduced ejection fraction (HFrEF) (n = 105) or with HF with a preserved ejection fraction (HFpEF) (n = 96). Phasic RA function was measured via volume measurements and feature-tracking methods to derive longitudinal strain. All-cause death was ascertained over a median follow-up of 38.9 months. Standardized hazard ratios (HRs) were computed via Cox regression.

RESULTS

Measures of RA phasic function were more prominently impaired in subjects with HFrEF than those in subjects with HFpEF. In analyses that adjusted for demographic factors, HF status, left ventricular ejection fraction, right ventricular end-diastolic volume index, and right ventricular ejection fraction, RA reservoir strain (HR: 0.66; 95% confidence interval [CI]: 0.47 to 0.92; p = 0.0154), RA expansion index (HR: 0.53; 95% CI: 0.31 to 0.91; p = 0.0116), RA conduit strain (HR: 0.58; 95% CI: 0.40 to 0.84; p = 0.0039), and RA conduit strain rate (HR: 1.51; 95% CI: 1.02 to 2.220; p = 0.0373) independently predicted all-cause mortality. In contrast, RA booster pump function and RA volume index did not independently predict the risk of death.

CONCLUSIONS

Phasic RA function is predictive of the risk of all-cause death in a diverse group of subjects with and without HF. RA conduit and reservoir function are independent predictors of mortality.

Right atrial structure and function in patients with hypertension and with chronic heart failure

BACKGROUND

Prior studies have shown that both heart failure (HF) and atrial fibrillation (AF) are factors that impact left atrial function and structure. However, right atrial (RA) function measured as RA emptying fraction (RAEF) on echocardiography has not been analyzed systematically in a chronic HF population. The aim of this study was to assess RA volume index (RAVI) and RAEF in patients with chronic HF and patients with hypertension (HTN) and to relate these findings to other cardiopulmonary ultrasound parameters and 12-month outcomes.

METHODS AND RESULTS

In this prospective observational study, we identified 119 patients with chronic HF (64 patients without a history of AF [HF without AF], 55 with AF [HF with AF]), and 127 patients with HTN but without important cardiac disease who underwent routine outpatient transthoracic echocardiography. We found that RAEF was impaired in patients with HF without AF compared to patients with HTN (35% ±2 vs 50% ±1, P < .001), whereas RAVI did not differ between these two groups. Lower RAEF was associated with larger RAVI and higher estimated RA pressures but not with a higher degree of pulmonary congestion by lung ultrasound. Both lower RAEF and higher RAVI were associated with an increased risk of 12-month HF hospitalizations or all-cause death (age, sex, and AF adjusted HR: 4.07, 95% CI: 1.69-9.79; P = .002, vs 2.74, 95% CI: 1.15-6.54, P = .023).

CONCLUSIONS

In an outpatient HF cohort, both lower RAEF and increased RAVI were associated with other markers of impaired cardiac function and 12-month adverse events.