Evaluation of the Graft Mechanical Function Using Speckle-Tracking Echocardiography During the First Year After Orthotropic Heart Transplantation

A Comprehensive Excursus of the Roles of Echocardiography in Heart Transplantation Follow-Up

Current guidelines for the care of heart transplantation recipients recommend routine endomyocardial biopsy and invasive coronary angiography as the cornerstones in the surveillance for acute rejection (AR) and coronary allograft vasculopathy (CAV). Non-invasive tools, including coronary computed tomography angiography and cardiac magnetic resonance, have been introduced into guidelines without roles of their own as gold standards. These techniques also carry the risk of contrast-related kidney injury. There is a need to explore non-invasive approaches providing valuable information while minimizing risks and allowing their application independently of patient comorbidities. Echocardiographic examination can be performed at bedside, serially repeated, and does not carry the burden of contrast-related kidney injury and procedure-related risk. It provides comprehensive assessment of cardiac morphology and function. Advanced echocardiography techniques, including Doppler tissue imaging and strain imaging, may be sensitive tools for the detection of minor myocardial dysfunction, thus providing insight into early detection of AR and CAV. Stress echocardiography may offer a valuable tool in the detection of CAV, while the assessment of coronary flow reserve can unravel coronary microvascular impairment and add prognostic value to conventional stress echocardiography. The review highlights the role of Doppler echocardiography in heart transplantation follow-up, weighting advantages and limitations of the different techniques.

Impact of bridging with left ventricular assist device on right ventricular function following heart transplantation

Aims

Patients awaiting orthotopic heart transplantation (OHT) can be bridged utilizing a left ventricular assist device (LVAD) that reduces left ventricular filling pressures, decreases pulmonary artery wedge pressure, and maintains adequate cardiac output. This study set out to examine the poorly investigated area of if and how pre‐treatment with LVAD impacts right ventricular (RV) function following OHT.

Methods and results

We prospectively evaluated 59 (LVAD n = 20) consecutive OHT patients. Transthoracic echocardiography (TTE) was performed in conjunction with right heart catheterization (RHC) at 1, 6, and 12 months after OHT. RV function TTE‐parameters included tricuspid annular plane systolic excursion (TAPSE), systolic tissue velocity (S′), fractional area change, two‐dimensional RV global longitudinal strain and longitudinal strain from the RV lateral wall (RVfree). At 1 month after OHT, the LVAD group had significantly better longitudinal RV function than the non‐LVAD group: TAPSE (15 ± 3 mm vs. 12 ± 2 mm, P < 0.001), RV global longitudinal strain (−19.8 ± 2.1% vs. −14.3 ± 2.8%, P < 0.001), and RVfree (−19.8 ± 2.3% vs. −14.1 ± 2.9%, P < 0.001). At this time point, pulmonary vascular resistance (PVR) was also lower [1.2 ± 0.4 Wood Units (WU) vs. 1.6 ± 0.6 WU, P < 0.05] in the LVAD group compared with the non‐LVAD group. At 6 and 12 months, no difference was detected in any of the TTE and RHC measured parameters between the two groups. Between 1 and 12 months, all parameters of RV function improved significantly in the non‐LVAD group but remained unaltered in the LVAD group.

Conclusions

Our results indicate that pre‐treatment with LVAD decreases PVR and is associated with significantly better RV function early following OHT. During the first year following transplantation, RV function progressively improved in the non‐LVAD group such that at 6 and 12 months, no difference in RV function was detected between the groups.

Donor-recipient predicted heart mass ratio and right ventricular-pulmonary arterial coupling in heart transplant

OBJECTIVES

Right ventricular-pulmonary arterial (RV-PA) coupling interactions are largely unexplored in heart transplant patients. The outcome of this study was RV-PA coupling at 7 and 30 days after heart transplant and its association with donor-recipient size matching.

METHODS

Clinical, echocardiographic and haemodynamic data from a retrospective cohort of heart transplant recipients and respective donors were reviewed. Coupling between RV-PA was examined by assessing the RV fractional area change and pulmonary artery systolic pressure ratio. Donor-recipient size matching was assessed by the predicted heart mass (PHM) ratio, and groups with a PHM ratio <1 and ≥1 were compared.

RESULTS

Forty-four heart transplant recipients were included in this study (50 years, 57% male sex). Postoperative RV-PA coupling improved from 7 to 30 days (RV fractional area change/pulmonary artery systolic pressure 0.9 ± 0.3 vs 1.2 ± 0.3; P < 0.001). A positive association was found between an adequate PHM ratio and improvement of RV fractional area change/pulmonary artery systolic pressure at 30 days, independent of graft ischaemic time and pre-existent pulmonary hypertension (B coefficient 0.54; 95% confidence interval 0.11-0.97; P = 0.016; adjusted R2 = 0.24).

CONCLUSIONS

These findings highlight the role of PHM as a metric to help donor selection and suggest its impact in RV-PA coupling interactions post-heart transplant.

Echocardiographic assessment of chamber size and ventricular function during the first year after heart transplantation

AIMS

Detecting changes in ventricular function after orthotopic heart transplantation (OHT) using transthoracic echocardiography (TTE) is important but interpretation of findings is complicated by lack of data on early graft adaptation. We sought to evaluate echocardiographic measures of ventricular size and function the first year following OHT including speckle tracking derived strain. We also aimed to compare echocardiographic findings to haemodynamic parameters obtained by right heart catheterization (RHC).

METHODS AND RESULTS

Fifty OHT patients were examined prospectively with TTE and RHC at 1, 6, and 12 months after OHT. Left ventricle (LV) was assessed with fractional shortening, ejection fraction and systolic tissue velocities. Right ventricular (RV) evaluation included tricuspid annular plane systolic excursion (TAPSE), systolic tissue velocity (S´) and fractional area change (FAC). LV global longitudinal and circumferential strain and RV global longitudinal strain (GLS) and RV lateral wall strain (RVfree) were analysed. No relevant changes occurred in LV echocardiographic parameters, whereas all measures of RV function improved significantly during follow-up. There was an increase in TAPSE (12.4 ± 3.3 mm to 14.4 ± 4.3 mm, p < .01), FAC (36% ± 8% to 41% ± 8%, p < .01), RV GLS (-15.8% ± 4% to -17.8% ± 3.6%, p < .01), and RVfree (-15.5% ± 3.7% to -18.6% ± 3.6%, p < .001). Between 1 and 12 months, pulmonary pressures decreased, whereas pulmonary vascular resistance did not.

CONCLUSION

Stable OHT recipients reached steady state regarding LV function 1 month after transplantation. In contrast, RV function displayed gradual improvement the first year following OHT, indicating delayed RV adaptation as compared to the LV. Improved RV function parameters were independent of invasively measured pulmonary pressures.

Diagnostic value of myocardial strain using two-dimensional speckle-tracking echocardiography in acute cardiac allograft rejection: A systematic review and meta-analysis

BACKGROUND

Two-dimensional speckle-tracking echocardiography (2D STE) has been demonstrated to have certain diagnostic utility in heart transplantation (HTX) patients with acute cardiac allograft rejection (ACAR). The aim of the systematic review and meta-analysis was to evaluate the diagnostic value of common strain parameters for ACAR in HTX patients.

METHODS

After conducting a database search, we selected studies evaluating left ventricular global longitudinal strain (GLS), circumferential strain (CS), radial strain (RS), and free wall right ventricular longitudinal strain (RV FW) in rejection group vs rejection-free group.

RESULTS

After reviewing 886 publications, seven studies were finally included in the meta-analysis, representing the data of 1173 pairs of endomyocardial biopsy and echocardiographic examination. Heart transplantation patients with rejection had significantly lower GLS than rejection-free subjects (weighted mean difference -2.32 (95% CI, -3.41 to -1.23; P < .001). Heart transplantation patients with rejection had significantly lower CS than rejection-free subjects (weighted mean difference -2.49 (95% CI, -4.05 to -0.91; P = .0019). In addition, HTX patients with rejection also had significantly lower RV FW (weighted mean difference -4.90 (95% CI, -6.15 to -3.65; P < .001).

CONCLUSIONS

The meta-analysis and systematic review demonstrate that myocardial strain parameters derived from 2D STE may be useful in detecting ACAR in HTX patients. The present results provide encouraging evidence to consider the routine use of GLS, CS, and RV FW as markers of graft function involvement during ACAR.

Multi-modal imaging of the pediatric heart transplant recipient

The assessment of pediatric patients after orthotropic heart transplantation (OHT) relies heavily on non-invasive imaging. Because of the potential risks associated with cardiac catheterization, expanding the role of non-invasive imaging is appealing. Echocardiography is fast, widely available, and can provide an accurate assessment of chamber sizes and function. Advanced echocardiographic methods, such as myocardial deformation, have potential to assess for acute rejection or cardiac allograft vasculopathy (CAV). While not currently part of routine care, cardiac magnetic resonance imaging (CMR) and computed tomography may potentially aid in the detection of graft complications following OHT. In particular, CMR tissue characterization holds promise for diagnosing rejection, while quantitative perfusion and myocardial late gadolinium enhancement may have a role in the detection of CAV. This review will evaluate standard and novel methods for non-invasive assessment of pediatric patients after OHT.

Clinical Applications of Echo Strain Imaging: a Current Appraisal

PURPOSE OF REVIEW

This article reviews recent advances in echocardiographic strain imaging, particularly in its ability to prognosticate in cardiovascular outcomes and impact clinical decision making.

RECENT FINDINGS

Strain has been proposed as a sensitive tool in detecting early ventricular dysfunction. Left ventricular global longitudinal strain (LV-GLS) detects subtle changes in myocardial function, often not quantifiable by ejection fraction alone. Thus, LV-GLS provides the opportunity for early decision-making, and the implementation of more effective treatments, improving outcomes in a variety of diseases such as valvular heart diseases, cardio-oncology, ischemic heart disease, cardiomyopathies, heart transplantation, and pericardial diseases and cardiomyopathies. Strain is a promising tool for the early detection of myocardial dysfunction in patients with preserved left ventricular ejection fraction and can prognosticate long-term outcomes.