Longitudinal Strain and Strain Rate for Estimating Left Ventricular Filling Pressure in Heart Transplant Recipients

Correlation Between Tissue Doppler Imaging Method (E/e') and Invasive Measurements of Left Ventricular Filling Pressures: A Systematic Review, Meta-Analysis, and Meta-Regression

OBJECTIVES

Evaluation of pulmonary capillary wedge pressure (PCWP) through right heart catheterization can indirectly provide an estimation of the filling pressure of the left ventricle. Echocardiography can estimate left ventricular compliance using mitral annular tissue Doppler imaging (TDI). The E/e' ratio refers to the correlation between the peak mitral inflow (E-wave) velocity and early diastolic tissue Doppler mitral annular velocity (e'). The main purpose of this systematic review was to establish the correlation between echocardiographic E/e' ratio and PCWP. The correlation between E/e' and left ventricular end-diastolic pressure (LVEDP) was evaluated as a secondary objective.

DESIGN

A systematic review and meta-analysis of observational studies was conducted. The search was based on Medline (PubMed), Scopus, and Web of Science.

SETTING

Intensive care unit or cardiac intensive care unit.

PARTICIPANTS

Adult patients.

INTERVENTIONS

Any study comparing the left ventricular filling pressure obtained by cardiac catheterization (reference) and echocardiographic evaluation, in particular TDI analysis (intervention), were included.

MEASUREMENTS AND MAIN RESULTS

The pooled analysis included 94 studies from the initially identified 7,304 records. The correlation was 0.48 (95% CI 0.42-0.54, Q = 420.52, I2 = 84.8%) for PCWP and 0.50 (95% CI 0.38-0.60, Q = 210.91, I2 = 89.1%) for LVEDP.

CONCLUSIONS

The E/e' ratio moderately correlated with PCWP/LVEDP. The correlation was stable irrespective of the sites where e' was measured, but each site has its own limitations for specific patient subpopulations. The correlation was weak in patients with heart failure with a preserved ejection fraction.

Myocardial Work by Speckle-Tracking Echocardiography in Heart Transplant Recipients: Association Between Global Work Efficiency and Coronary Allograft Vasculopathy

Coronary allograft vasculopathy (CAV) is a leading cause of morbidity and mortality after heart transplantation. CAV is often diagnosed in later stages or during routine screening in asymptomatic subjects. Myocardial work (MW), calculated using left ventricular global longitudinal strain (LV-GLS) and systemic blood pressure, may be associated with the presence of CAV and outperform conventional echocardiographic parameters. In this retrospective observational study, heart transplant recipients who underwent regular follow-up at our institution between May 2022 and September 2023 were enrolled. All included patients underwent speckle-tracking echocardiography, including MW indexes. CAV was classified according to invasive coronary angiography or computed tomography performed within 12 months of index echocardiography. We collected all available clinical and echocardiographic parameters and evaluated the potential association with CAV. CAV was detected in 29 of 93 patients (31%) (CAV+). Of the MW indexes, the mean global work efficiency (GWE) was 90 ± 6% and was significantly lower in CAV+ than CAV- subjects (86 ± 7% vs 91 ± 4%, p <0.001). GWE (OR 0.86, CI 0.77 to 0.94, p = 0.002), E/e' ratio (OR 1.27, CI 1.08 to 1.52, p = 0.006), and left ventricular ejection fraction (OR 0.90; CI 0.81 to 0.98, p = 0.017) were independently associated with the presence of CAV. GWE (GWE vs LV-GLS, delta area under the curve 0.154, p = 0.047) and the proposed model (GWE+E/e' vs LV-GLS, delta area under the curve 0.198, p = 0.004) were significantly superior in stratifying the incremental risk for CAV compared with LV-GLS. In conclusion, GWE was observed to be independently associated with the presence of CAV. MW could represent a novel noninvasive screening method for CAV in heart transplant recipients. Larger and prospective studies are needed to confirm this hypothesis.

A machine learning-derived risk score to predict left ventricular diastolic dysfunction from clinical cardiovascular magnetic resonance imaging

Introduction

The evaluation of left ventricular diastolic dysfunction (LVDD) by clinical cardiac magnetic resonance (CMR) remains a challenge. We aimed to train and evaluate a machine-learning (ML) algorithm for the assessment of LVDD by clinical CMR variables and to investigate its prognostic value for predicting hospitalized heart failure and all-cause mortality.

Methods

LVDD was characterized by echocardiography following the ASE guidelines. Eight demographic and nineteen common clinical CMR variables including delayed enhancement were used to train Random Forest models with a Bayesian optimizer. The model was evaluated using bootstrap and five-fold cross-validation. Area under the ROC curve (AUC) was utilized to evaluate the model performance. An ML risk score was used to stratify the risk of heart failure hospitalization and all-cause mortality.

Results

A total of 606 consecutive patients underwent CMR and echocardiography within 7 days for cardiovascular disease evaluation. LVDD was present in 303 subjects by echocardiography. The performance of the ML algorithm was good using the CMR variables alone with an AUC of 0.868 (95% CI: 0.811-0.917), which was improved by combining with demographic data yielding an AUC 0.895 (95% CI: 0.845-0.939). The algorithm performed well in an independent validation cohort with AUC 0.810 (0.731-0.874). Subjects with higher ML scores (>0.4121) were associated with increased adjusted hazard ratio for a composite outcome than subjects with lower ML scores (1.72, 95% confidence interval 1.09-2.71).

Discussion

An ML algorithm using variables derived from clinical CMR is effective in identifying patients with LVDD and providing prognostication for adverse clinical outcomes.

Myocardial mechanics and cardiac biomarkers in adults with severe anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is associated with left ventricular (LV) atrophy and unexplained sudden death. Myocardial mechanics have not been well studied in adults with AN. Whether LV mass or illness duration, markers of AN severity, correlate with abnormal strain imaging is unknown.

METHODS

We performed a prospective study among patients hospitalized with severe AN (n = 29) [body mass index (BMI) < 14.5 kg/m2] and sex/age-matched controls (n = 16) (BMI > 18.5 kg/m2). LV ejection fraction (LVEF) was calculated via modified-biplane method and LV mass was derived using the truncated ellipsoid formula. Apical 2-, 3-, and 4-chamber images were used to generate regional strain mapping and global longitudinal strain (GLS). N-terminal brain natriuretic peptide (NT-proBNP) levels were measured and linear regression was used to determine independent predictors of strain.

RESULTS

Mean LVEF did not differ (65% ± 6.0 vs. 62% ± 4.4, p = 0.06), but LV mass was substantially reduced (61.6 ± 16.8 vs. 97.6 ± 19.1 g, p < .0001). GLS was similar (- 20.6 ± 3.8 vs. - 20.9 ± 2.8, p = 0.82), however, the basal strain was worse (-18.7 ± 4.8 vs. -21.9 ± 4.1, p = 0.03). Lower LV mass was associated with worsening GLS (r = - 0.40, p = 0.003), but not among controls (p = 0.89). Median (IQR) NT-proBNP (pg/ml) was higher in patients with AN [141 (59-257) vs. 35.5 (21-56.5) p = 0.0007]. Both increasing NT-proBNP and illness duration were associated with worsening strain patterns in AN (both p = .001).

CONCLUSIONS

While LVEF and GLS did not differ, regional strain variation was noted among patients with AN. Elevated NT-proBNP may reflect increased wall tension from LV atrophy. Whether strain heterogeneity can identify patients with AN, at risk for sudden death, requires further study.

Echocardiographic assessment of pulmonary capillary wedge pressure by E/e' ratio: A systematic review and meta-analysis

BACKGROUND

The reliability of echocardiographic methods for the assessment of pulmonary capillary wedge pressure (PCWP) is still a matter of debate. Since its first description, the E/e' ratio has been regarded as a suitable method. The aim of this study is to evaluate the evidence of how E/e' effectively estimates PCWP and its diagnostic accuracy for elevated PCWP.

METHODS

We systematically searched MEDLINE and Embase databases for studies investigating the agreement between E/e' and PCWP, from inception to July 2022. We limited our research to studies published from 2010 to date. Retrospective studies and studies on non-adult population were excluded.

RESULTS

Twenty-eight studies, involving a total of 1964 subjects, were included. The pooled analysis of the studies showed a modest correlation between E/e' and PCWP. The weighted average correlation (r) is 0.43 (95% CI 0.37-0.48). We found no significant differences between reduced and preserved ejection fraction groups. Thirteen studies analysed the diagnostic accuracy of E/e' for elevated PCWP. The AUC of receiver operating characteristic curves for PCWP >15 mmHg was estimated in the interval 0.6-0.91.

DISCUSSION

E/e' appears to have a modest correlation with PCWP and an acceptable accuracy for elevated PCWP. (PROSPERO number, CRD42022333462).

Diastolic function in heart transplant: From physiology to echocardiographic assessment and prognosis

Heart transplant (HTx) still represents the most effective therapy for end-stage heart failure, with a median survival time of 10 years. The transplanted heart shows peculiar physiology due to the profound alterations induced by the operation, which inevitably influences several echocardiographic parameters assessed during these patients’ follow-ups. With these premises, the diastolic function is one of the main aspects to take into consideration. The left atrium (LA) plays a key role in this matter, and that same chamber is significantly impaired with the transplant, with different degrees of altered function based on the surgical technique. Therefore, the traditional echocardiographic evaluation of diastolic function applied to the general population might not properly reflect the physiology of the graft. This review attempts to provide current evidence on diastolic function in HTx starting from defining its different physiology and how the standard echocardiographic parameters might be affected to its prognostic role. Furthermore, based on the experience of our center and the available evidence, we proposed an algorithm that might help clinicians distinguish from actual diastolic dysfunction from a normal diastolic pattern in HTx population.

Associations between Subclinical Myocardial Dysfunction and Premature Fusion of Early and Late Diastolic Filling with Uncertain Cause

PURPOSE

The fusion of early (E) and late diastolic filling (A) on mitral inflow Doppler, even in the absence of tachycardia, is often found during assessment of left ventricular (LV) diastolic function. We evaluated the echocardiographic characteristics and clinical implications of premature E-A fusion of uncertain cause in the absence of tachycardia.

MATERIALS AND METHODS

We identified 1014 subjects who showed E-A fusion and normal LV ejection fraction (LVEF) between January 2019 and June 2021 at two tertiary hospitals. Among these, 105 (10.4%) subjects showed premature E-A fusion at heart rates less than 100 beats per minute (bpm). The conventional echocardiographic parameters and LV global longitudinal strain (GLS) were compared with 1:1 age-, sex-, and heart rate-matched controls without E-A fusion.

RESULTS

The premature E-A fusion group had a heart rate of 96.4±3.7 bpm. Only 4 (3.8%) subjects were classified as having LV diastolic dysfunction according to current guidelines. The group showed prolonged isovolumic relaxation time (107.2±25.3 msec vs. 61.6±15.6 msec, p<0.001), increased Tei index (0.76±0.19 vs. 0.48±0.10, p<0.001), lower LVEF (63.8±7.0% vs. 67.3±5.6%, p<0.001) and lower absolute LV GLS (|LV GLS|) (17.0±4.2% vs. 19.7±3.3%, p<0.001) than controls. As the E-A fusion occurred at lower heart rate, the |LV GLS| was also lower (p for trend=0.002).

CONCLUSION

Premature E-A fusion at heart rates less than 100 bpm is associated with subclinical LV dysfunction. Time-based indices and LV GLS are helpful for evaluating this easily overlooked population.