Evaluation of longitudinal myocardial deformation by 2-dimensional speckle-tracking echocardiography in heart transplant recipients: relation to coronary allograft vasculopathy

Echocardiographic Evaluation of the Post-Heart Transplant Patient

PURPOSE OF REVIEW

Significant practice variability exists with respect to the role and frequency of echocardiography after heart transplantation. We sought to illustrate key studies relating to the utility and diagnostic accuracy of echocardiography for the post-heart transplant patient.

RECENT FINDINGS

Several echocardiographic parameters correlate with acute heart transplant rejection, but there is enough heterogeneity between study results or in diagnostic accuracy, such that it precludes parameter use in isolation to rule out rejection. Newer techniques such as strain echocardiography may have better sensitivity. Similarly, resting and stress echocardiography can be combined with modern techniques such as myocardial contrast echocardiography to diagnose and prognosticate cardiac allograft vasculopathy, but studies have again demonstrated variable accuracy. Echocardiography remains an accessible tool in the evaluation and management of patients after heart transplantation. This modality can guide clinical judgment with real-time data and several fairly sensitive parameters for the detection of rejection, cardiac allograft vasculopathy, and other abnormalities. Often, auxiliary diagnostic modalities need to be combined to optimize diagnostic accuracy.

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.

Non-invasive myocardial tissue deformation and discoordination indices predict cardiac allograft vasculopathy in pediatric heart transplantation patients

There is an urgent need for non-invasive imaging-based biomarkers suitable for diagnostic surveillance of cardiac allograft vasculopathy (CAV) in pediatric heart transplant (PHT) patients. The purpose of this study was to comprehensively investigate left ventricular (LV) myocardial deformation in conjunction with electromechanical discoordination in PHT. PHT patients with and without CAV were evaluated for echocardiography derived global longitudinal strain (GLS) and electromechanical discoordination indices including systolic stretch fraction (SSF) and diastolic relaxation fraction (DRF). SSF was increased in CAV(+) patients at the time of CAV diagnosis (median CAV(+) 5.0 vs. median CAV(-) 0.0, P = 0.008) and in the echocardiogram preceding the CAV diagnosis (median CAV(+) 29.0 vs. median CAV(-) 0.0, P < 0.001). DRF was also increased in the echocardiogram that preceded CAV diagnosis in CAV(+) patients (0.31 ± 0.08 vs. 0.25 ± 0.05, P = 0.008). The final model using indices 6-12 months prior to CAV diagnosis included GLS, SSF, and DRF providing AUC of 0.94 with sensitivity 98.5%, specificity 80.0%, positive predictive value 85.0%, and negative predictive value 94.1%. Systolic and diastolic electro-mechanical discoordination indices are significantly worse in PHT patients experiencing CAV. Non-invasive imaging guided surveillance using echocardiographic myocardial deformation indices can be improved by adding SSF and DRF to standard GLS measurements.

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.

New Non-Invasive Imaging Technologies in Cardiac Transplant Follow-Up: Acquired Evidence and Future Options

Heart transplantation (HT) is the established treatment for end-stage heart failure, significantly enhancing patients' survival and quality of life. To ensure optimal outcomes, the routine monitoring of HT recipients is paramount. While existing guidelines offer guidance on a blend of invasive and non-invasive imaging techniques, certain aspects such as the timing of echocardiographic assessments and the role of echocardiography or cardiac magnetic resonance (CMR) as alternatives to serial endomyocardial biopsies (EMBs) for rejection monitoring are not specifically outlined in the guidelines. Furthermore, invasive coronary angiography (ICA) is still recommended as the gold-standard procedure, usually performed one year after surgery and every two years thereafter. This review focuses on recent advancements in non-invasive and contrast-saving imaging techniques that have been investigated for HT patients. The aim of the manuscript is to identify imaging modalities that may potentially replace or reduce the need for invasive procedures such as ICA and EMB, considering their respective advantages and disadvantages. We emphasize the transformative potential of non-invasive techniques in elevating patient care. Advanced echocardiography techniques, including strain imaging and tissue Doppler imaging, offer enhanced insights into cardiac function, while CMR, through its multi-parametric mapping techniques, such as T1 and T2 mapping, allows for the non-invasive assessment of inflammation and tissue characterization. Cardiac computed tomography (CCT), particularly with its ability to evaluate coronary artery disease and assess graft vasculopathy, emerges as an integral tool in the follow-up of HT patients. Recent studies have highlighted the potential of nuclear myocardial perfusion imaging, including myocardial blood flow quantification, as a non-invasive method for diagnosing and prognosticating CAV. These advanced imaging approaches hold promise in mitigating the need for invasive procedures like ICA and EMB when evaluating the benefits and limitations of each modality.

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.

Prognostic Value of Left and right ventricular deformation strain analysis on Acute Cellular rejection in Heart Transplant recipients: A 6-year outcome study

PURPOSE

Two-dimensional (2D) strain analysis is a sensitive method for detecting myocardial dysfunction in acute cellular rejection (ACR) from post-transplant complications. This study aims to evaluate the utility of novel left (LV) and right ventricular (RV) strain parameters for prognostic risk stratification associated with ACR burden at 1-year post transplantation.

METHODS

128 Heart transplant patients, assessed between 2012 and 2018, underwent transthoracic echocardiography and endomyocardial biopsy. 2D strain analysis was performed and history of rejection burden was assessed and grouped according to ACR burden at 1-year post transplantation. The primary endpoint was all-cause mortality at 6-years follow up.

RESULTS

21 patients met primary the endpoint. Multivariate analysis of 6-year all-cause mortality showed LV global longitudinal strain (LV GLS) (Hazard Ratio [HR] = 1.21, CI = 1.06-1.49), LV early diastolic strain rate (LV ESr) (HR = 1.31, CI = 1.12-1.54), RV GLS (HR = 1.12, CI = 1.02-1.25) and RV ESr (HR = 1.26, CI = 1.12-1.47) were significant predictors of outcome. Univariate analysis also showed LV GLS, LV ESr, RV GLS and RV ESr were significant predictors of outcome. Optimal cut-off for predicting 6-year mortality for LV GLS by receive operator characteristic was 15.5% (sensitivity: 92%, specificity: 79%). Significant reductions (p < 0.05) in LV GLS, RV GLS and LV and RV ESr between rejection groups were seen.

CONCLUSIONS

Non-invasive LV and RV strain parameters are predictors of mortality in post-transplant patient with ACR. LV GLS and LV ESr are superior to other strain and conventional echo parameters.

The Role of Echocardiography in the Management of Heart Transplant Recipients

Transthoracic echocardiography is the primary non-invasive modality for the investigation of heart transplant recipients. It is a versatile tool that provides comprehensive information on cardiac structure and function. Echocardiography is also helpful in diagnosing primary graft dysfunction and evaluating the effectiveness of therapeutic approaches for this condition. In acute rejection, echocardiography is useful with suspected cellular or antibody-mediated rejection, with findings confirmed and quantified by endomyocardial biopsy. For identifying chronic rejection, ultrasound has a more significant role and, in some specific patients (e.g., patients with renal failure), it may offer a role comparable to coronary angiography to identify cardiac allograft vasculopathy. This review highlights the usefulness of echocardiography in evaluating normal graft function and its role in the management of heart transplant recipients.

Diagnostic and Prognostic Value of a TDI-Derived Systolic Wall Motion Analysis as a Screening Modality for Allograft Rejection after Heart Transplantation

Background: Despite the risk for complications, allograft surveillance after orthotopic heart transplantation (OHT) is performed by cardiac catheterization and biopsies. We investigated the diagnostic and prognostic value of a TDI-derived systolic wall motion analysis of the posterobasal wall of the left ventricle (Sm) as a screening modality in OHT aftercare. Methods: We examined data of 210 eligible patients who underwent OHT between 2010 and 2020. Forty-four patients who had died within the initial hospital stay were excluded. For 166 patients, baseline and follow-up data were analyzed. The mean age at OHT was 46.2 (±11.4) years; 76.5% were male. Results: Within the observational period, 22 (13.3%) patients died. In total, 170 episodes of acute cellular or humoral rejections occurred (84 ISHLT1R; 13 ISHLT2R; 8 ISHLT3R; 65 AMR), and 29 catheterizations revealed cardiac allograft vasculopathy (5 CAV1; 4 CAV2; 20 CAV3). Individual Sm radial/longitudinal remained stable within the follow-up period (11.5 ± 2.2 cm/s; 10.9 ± 2.1 cm/s). Patients with acute rejections and CAV3 showed significant Sm radial/longitudinal reductions (AMR1: 1.6 ± 1.9 cm/s, confidence interval (CI) 0.77–0.243, p < 0.001; 1.8 ± 2.0 cm/s, CI 0.92–0.267, p < 0.001. ISHLT1R: 1.7 ± 1.8 cm/s, CI 1.32–2.08, p < 0.001; 2.0 ± 1.6 cm/s, CI 1.66–2.34, p < 0.001. CAV3: 1.3 ± 2.5 cm/s, CI 0.23–2.43, p < 0.017; 1.4 ± 2.8 cm/s, CI 0.21–2.66, p < 0.021). Lower Sm was associated with a threefold increase in all-cause mortality (hazard ratio (HR) 3.24, CI 1.2–8.76, p = 0.020; HR 2.92, CI 1.19–7.18, p = 0.019). Overall, Sm-triggered surveillance led to 0.75 invasive diagnostics per patient post-OHT year. Conclusions: Sm remained stable in the post-OHT course. Reductions indicated ISHLT1R, AMR1 and CAV3 and were associated with higher all-cause mortality. Sm-triggered surveillance may be referred to as a safe, high-yield screening modality in OHT aftercare.

The role of non-invasive imaging modalities in cardiac allograft vasculopathy: an updated focus on current evidences

Cardiac allograft vasculopathy (CAV) is an obliterative and diffuse form of vasculopathy affecting almost 50% of patients after 10 years from heart transplant and represents the most common cause of long-term cardiovascular mortality among heart transplant recipients. The gold standard diagnostic technique is still invasive coronary angiography, which however holds potential for complications, especially contrast-related kidney injury and procedure-related vascular lesions. Non-invasive and contrast-sparing imaging techniques have been advocated and investigated over the past decades, in order to identify those that could replace coronary angiography or at least reach comparable accuracy in CAV detection. In addition, they could help the clinician in defining optimal timing for invasive testing. This review attempts to examine the currently available non-invasive imaging techniques that may be used in the follow-up of heart transplant patients, spanning from echocardiography to nuclear imaging, cardiac magnetic resonance and cardiac computed tomography angiography, weighting their advantages and disadvantages.

Coronary Flow Velocity Reserve and Myocardial Deformation Predict Long-Term Outcomes in Heart Transplant Recipients

BACKGROUND

After heart transplantation (HTx), invasive coronary angiography is the gold standard for surveillance of cardiac allograft vasculopathy (CAV). Noninvasive CAV surveillance is desirable. The authors examined left ventricular global longitudinal strain (LVGLS) and noninvasive coronary flow velocity reserve (CFVR) related to CAV and prognosis after HTx.

METHODS

Doppler echocardiographic CFVR and LVGLS were evaluated in 98 HTx patients. All-cause mortality and major adverse cardiac events (MACE), including hospitalization for heart failure, cardiovascular death, and significant CAV progression, were recorded.

RESULTS

Median follow-up duration was 3.3 years (range: 1.7-5.4 years). Patients with low CFVR (<2.0; n = 20) showed reduced MACE-free survival (hazard ratio, 4.3; 95% CI, 2.2-8.4; P < .0001) and increased all-cause mortality (hazard ratio: 4.7; 95% CI: 2.0-11.3; P < .0001) compared with patients with high CFVR (≥2.0; n = 78). Worsened LVGLS (≥-15.5%) was also a strong independent predictor of MACE and cardiovascular and all-cause mortality. Combined low CFVR and worsened LVGLS provided incremental prognostic value, even after adjustment for CAV and time since HTx. The prevalence of low CFVR increased significantly with CAV severity, and the prevalence of combined low CFVR and/or worsened LVGLS was high in patients with moderate CAV (86%) and those with severe CAV (83%). The negative predictive value of combined high CFVR and improved LVGLS to rule out significant CAV was 94.5% (95% CI, 86.2%-98.4%), whereas the positive predictive value was 39.0% (95% CI, 25.3%-54.3%). The model had sensitivity of 84.2% (95% CI, 63.6%-95.3%) and specificity of 67.5% (95% CI, 56.6%-77.2%) for one or more abnormal parameters.

CONCLUSIONS

In HTx patients with severe CAV, a higher prevalence of low CFVR and worsened LVGLS was observed. Both measurements were strong independent predictors of MACE and all-cause mortality in HTx patients. Combined CFVR and LVGLS provided incremental prognostic value and showed an excellent ability to rule out significant CAV and may be considered as part of routine CAV surveillance of HTx patients.

Pediatric heart transplantation: how to manage problems affecting long-term outcomes?

Since the initial International Society of Heart Lung Transplantation registry was published in 1982, the number of pediatric heart transplantations has increased markedly, reaching a steady state of 500-550 transplantation annually and occupying up to 10% of total heart transplantations. Heart transplantation is considered an established therapeutic option for patients with end-stage heart disease. The long-term outcomes of pediatric heart transplantations were comparable to those of adults. Issues affecting long-term outcomes include acute cellular rejection, antibody-mediated rejection, cardiac allograft vasculopathy, infection, prolonged renal dysfunction, and malignancies such as posttransplant lymphoproliferative disorder. This article focuses on medical issues before pediatric heart transplantation, according to the Korean Network of Organ Sharing registry and as well as major problems such as graft rejection and cardiac allograft vasculopathy. To reduce graft failure rate and improve long-term outcomes, meticulous monitoring for rejection and medication compliance are also important, especially in adolescents.

Imaging of Cardiac Transplantation: An Overview

Heart transplantation (HTx) remains the optimal treatment for selected patients with end-stage advanced heart failure. However, survival is limited early by acute rejection and long term by cardiac allograft vasculopathy (CAV). Even though the diagnosis of rejection is based on histology, cardiac imaging provides a pivotal role for early detection and severity assessment of these hazards. The present review focuses on the use and reliability of different invasive and non-invasive imaging modalities to detect and monitor CAV and rejection after HTx. Coronary angiography remains the corner stone in routine CAV surveillance. However, angiograms are invasive and underestimates the CAV severity especially in the early phase. Intravascular ultrasound and optical coherence tomography are invasive methods for intracoronary imaging that detects early CAV lesions not evident by angiograms. Non-invasive imaging can be divided into myocardial perfusion imaging, anatomical/structural imaging and myocardial functional imaging. The different non-invasive imaging modalities all provide clinical and prognostic information and may have a gatekeeper role for invasive monitoring. Acute rejection and CAV are still significant clinical problems after HTx. No imaging modality provides complete information on graft function, coronary anatomy and myocardial perfusion. However, a combination of invasive and non-invasive modalities at different stages following HTx should be considered for optimal personalized surveillance and risk stratification.

Detection of cardiac allograft vasculopathy by multi-layer left ventricular longitudinal strain in heart transplant recipients

Cardiac allograft vasculopathy (CAV) is an obliterative and diffuse type of coronaropathy that develops in the transplanted human heart, representing a major cause of graft failure and mortality. Nowadays the gold standard for the diagnosis of CAV is coronary angiography (CA). Non-invasive CAV detection, especially in the early stages of the disease, is still challenging. Our study aimed to investigate the role of speckle tracking echocardiography (STE), in particular three-layer STE, in predicting CAV at early stages, and if other traditional echocardiographic, clinical or biochemical parameters could relate to CAV. The study population was composed of a total of 33 heart transplanted patients, divided accordingly to the presence or absence of CAV (12 CAV+ , 22 CAV-). All subjects underwent a complete transthoracic echocardiographic examination on the same day of the CA, and all conventional parameters of myocardial function were obtained, including strain values assessed by STE. Strain values were significantly reduced in presence of CAV, at each myocardial layer but in particular the endocardial-epicardial gradient (- 4.15 ± 1.6 vs - 1.7 ± 0.4% < .0001) that was also highly predictive of CAV (AUC at ROC curve 0.97). Among diastolic parameters, the E wave deceleration time (DT) and the mean E/e' ratio were strongly positively associated with CAV. In our population, left ventricular global longitudinal strain (GLS), layer-specific GLS and the endocardial-epicardial LS gradient, E wave DT and E/e' ratio were the best independent non-invasive predictors of CAV.

Predictive Parameters of Decreased Left Ventricular Global Longitudinal Strain at 1 Month After Pediatric Heart Transplantation

Previous reports indicate that the decreased left ventricular global longitudinal strain (LVGLS) seen in the early postoperative period of pediatric heart transplant patients generally recovers over the course of 1-2 years. In this study, we investigate the predictive capacity of preoperative parameters on the LVGLS decline seen at 1 month post transplant. Forty-six transplant subjects with 2D echocardiographic images sufficient for speckle tracking echocardiography were enrolled. We excluded patients diagnosed with cardiac allograft vasculopathy or with an episode of rejection 1 month before or after their echocardiographic examinations. The mean LVGLS was significantly reduced at 1 month when compared to 1 year following transplant (- 15.5% vs. - 19.4%, respectively, p < 0.001). The predictors of LVGLS that decline at 1 month were the LV mass z-score [odds ratio (OR) 1.452; 95% confidence interval (CI) 1.007-2.095, p = 0.046], recipient age (OR 1.124; 95% CI 1.015-1.245, p = 0.025), and donor age (OR 1.081; 95% CI 1.028-1.136, p = 0.002) in the univariate logistic regression analyses. Although multivariate analysis yielded no significant predictors, higher LV mass z-scores showed a trend associated with the decline of LVGLS (p = 0.087). The donor/recipient weight ratio was associated with the LV mass z-score (R² = 0.412, p < 0.001).

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

Traditional parameters have limited value to estimate left ventricular filling pressure (LVFP) in orthotropic heart transplant (OHT) recipients. We hypothesized that global longitudinal strain (GLS), diastolic, and systolic strain rate (SR) would be depressed in OHT recipients with elevated LVFP and could overcome the limitations of traditional parameters. We studied consecutively OHT patients at the time of endomyocardial biopsies and retrospectively pretransplantation studies conforming to the same protocol. Comprehensive echocardiography with strain measurements was performed. Results were compared with pulmonary capillary wedge pressure (PCWP) obtained from right heart catheterization that was performed just after the echocardiography study. In all, 74 studies were performed in 50 OHT recipients. Mean PWCP was 11.8 ± 4.3 mm Hg (range: 4 to 25 mm Hg). Several parameters, but not left atrial volume index, mitral inflow velocities, annular velocities, and their ratio (E/e'), were different between studies with normal (n = 47) and elevated PCWP (n = 27). Area Under Curve for GLS (0.932*), E/e'_SR (0.849*), and systolic SR (0.848*) (*p <0.0001) were more accurate than traditional parameters for predicting PCWP>12 mm Hg. GLS, systolic SR and E/e'_SR remained accurate regardless of LV ejection fraction and allograft vasculopathy. Meanwhile, E/e' was accurate to predict PWCP in native failing hearts before transplantation. Changes in GLS and E/e'_SR tracked accurately changes in PCWP. In conclusion, traditional indices of diastolic function perform poorly in OHT recipients, whereas GLS and E/e'_SR provide reliable means of LVFP, irrespective of ejection fraction and allograft vasculopathy. These parameters also track reasonably well the changes in LVFP.

Evaluation of Biventricular Functions in Transplanted Hearts Using 3-Dimensional Speckle-Tracking Echocardiography

Background The current study aims to validate the accuracy of 3-dimensional speckle-tracking echocardiography (3D-STE) in evaluating biventricular functions against the accuracy of cardiac magnetic resonance (CMR) and to explore the comprehensive characteristics and normal values for 3D-biventricular functions in transplanted hearts. Methods and Results A cohort of 35 heart transplant (HT) patients underwent both 3D echocardiography and CMR examination to validate the accuracy of 3D-STE in evaluating biventricular functions (Protocol 1). Then, 3D-STE derived biventricular functions were compared between 46 HT patients and 46 non-HT controls (Protocol 2). Protocol 1, validated that 3D-STE showed excellent accuracy in evaluating biventricular functions of transplanted hearts against CMR. Protocol 2, revealed lower (normal range) 3D-biventricular ejection fractions in HT patients than in controls (P<0.001). 3D-left ventricular global longitudinal strain, left ventricular-global circumferential strain, left ventricular-global radial strain, left ventricular-global performance index and right ventricular free-wall longitudinal strain were all lower in the HT patients than in healthy controls (P<0.001). Further, these strain values were all good for differentiating between groups (areas under the curve: 0.80-0.94, P<0.001). Moreover, left ventricular-lateral-wall radial displacement was higher and septal-wall radial displacement was lower in the HT group than in control group (P<0.001). Conclusions Compared with cardiac magnetic resonance, 3D-STE can evaluate biventricular functions of transplanted hearts accurately; 3D-biventricular mechanical functions are reduced even in clinically well HT patients. The provided characteristics and appropriate normal values of biventricular functions can be the basis for detection of ventricular dysfunction during follow-ups and further studies on transplanted hearts.

Cardiovascular magnetic resonance-derived myocardial strain in asymptomatic heart transplanted patients and its correlation with late gadolinium enhancement

OBJECTIVES

To investigate whether cardiovascular magnetic resonance (CMR)-derived myocardial strains were abnormal in asymptomatic heart transplant (HT) patients with normal left ventricular ejection fraction (LVEF) and to detect the relationship between CMR-derived myocardial strain parameters and late gadolinium enhancement (LGE) in asymptomatic HT patients.

METHODS

A total of 72 HT patients and 35 healthy volunteers underwent 1.5-T MR scanning. The examination protocol included basic cine imaging and LGE. The deformation registration algorithm (DRA) and feature tracking (FT) software were used for the strain analyses. Myocardial strain measurements included left ventricular global longitudinal strain (LVGLS), LV global circumferential strain (LVGCS), LV global radial strain (LVGRS) and right ventricular longitudinal strain (RVLS).

RESULTS

Compared with healthy volunteers, HT patients had significantly decreased DRA- and FT- derived myocardial strain measurements (all p < 0.05). There was a significant correlation and high reproducibility between the DRA- and FT-derived strain parameters. Both CMR-derived LVGLS and LVGRS were significantly related to the presence of LGE, and multivariate logistic regression analyses showed that the LVGLS measurement obtained from both techniques was independently associated with the presence of LGE. The odds ratios (ORs) for DRA- and FT-LVGLS were 1.340 and 1.342, respectively.

CONCLUSIONS

Asymptomatic HT patients with preserved LVEF exhibited reduced myocardial strain parameters. The CMR-derived LVGLS was independently related to the presence of LGE in HT patients.

KEY POINTS

• Reduced myocardial strain parameters were found in asymptomatic heart transplanted (HT) patients with normal left ventricular ejection fraction (LVEF). • The deformation registration algorithm (DRA) and feature tracking (FT)-derived strains in asymptomatic HT patients had high reproducibility. • DRA- and FT-derived LVGLS had an independent relationship with late gadolinium enhancement (LGE) in asymptomatic HT patients.

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.

Left ventricular adaptation following orthotopic heart transplantation in children: A speckle tracking echocardiographic imaging study

BACKGROUND

Evolution of left ventricle (LV) function in the pediatric OHT population has not been well described. Our hypothesis was that, in children following OHT without any rejection, there would be progressive normalization of LV size and function over 2 years.

METHODS

LV function was evaluated using STE and conventional echo parameters at five time points in pediatric OHT patients without any rejection in the first 2 years following OHT and normal controls. LV global peak systolic longitudinal strain (LVPLS) and strain rate, LV peak systolic radial and circumferential strain (LVRS and LVCS), and strain rate were analyzed.

RESULTS

We had twenty two patients with median age at OHT of 1.27 years ( IQR 0.19, 5.6 years). The LVPLS (mean ± SD) was abnormal in the post-OHT echocardiograms at 1 week (-12.4 ± 3.7) and 1 month (-13.9 ± 3.7) and significantly improved at 6 months (-15.8 ± 3.2), 1 year (-15.7 ± 3.1), and 2 years (-17.8 ± 2.8). However, LVPLS remained below the normal group even at 2 years following OHT (-21.3 ± 1.76).

CONCLUSION

In children following OHT, despite the absence of rejection, strain values are significantly impaired in the initial months, improve progressively over the first 2 years but remain abnormal compared with healthy controls.

Temporal changes in left ventricular strain with the development of rejection in paediatric heart transplant recipients

INTRODUCTION

Myocardial strain measurements are increasingly used to detect complications following heart transplantation. However, the temporal association of these changes with allograft rejection is not well defined. The aim of this study was to describe the evolution of strain measurements prior to the diagnosis of rejection in paediatric heart transplant recipients.

METHODS

All paediatric heart transplant recipients (2004-2015) with at least one episode of acute rejection were identified. Longitudinal and circumferential strain measurements were assessed at the time of rejection and retrospectively on all echocardiograms until the most recent negative biopsy. Smoothing technique (LOESS) was used to visualise the changes of each variable over time and estimate the time preceding rejection at which alterations are first detectable.

RESULTS

A total of 58 rejection episodes were included from 37 unique patients. In the presence of rejection, there were decrements from baseline in global longitudinal strain (-18.2 versus -14.1), global circumferential strain (-24.1 versus -19.6), longitudinal strain rate (-1 versus -0.8), circumferential strain rate (-1.3 versus -1.1), peak longitudinal early diastolic strain rate (1.3 versus 1), and peak circumferential early diastolic strain rate (1.5 versus 1.3) (p<0.01 for all). The earliest detectable changes occurred 45 days prior to rejection with simultaneous alterations in myocardial strain and ejection fraction.

CONCLUSIONS

Changes in graft function can be detected non-invasively prior to the diagnosis of rejection. However, changes in strain occur concurrently with a decline in ejection fraction. Strain measurements aid in the non-invasive detection of rejection, but may not facilitate earlier diagnosis compared to more traditional measures of ventricular function.

Prognostic value of exercise myocardial deformation and haemodynamics in long-term heart-transplanted patients

Aims

The study evaluated exercise left ventricular global longitudinal strain (LVGLS) and invasive haemodynamics for major adverse cardiac events (MACE) prediction in heart‐transplanted (HTx) patients.

Methods and results

The study comprised 74 stable consecutive HTx patients who were followed at the Department of Cardiology, Aarhus University Hospital, Denmark, from August 2013 to January 2017. All patients were transplanted a minimum of 12 months before study entry and were included at the time of their routine annual coronary angiography. A symptom‐limited haemodynamic exercise test with simultaneous echocardiographic study was performed. The primary endpoint was MACE during follow‐up defined as heart failure hospitalization, treated rejection episodes, coronary event, or cardiac death.

The median time since transplant was 5 years [1:12] and the median follow‐up was 1095 days [391;1506]. Thirty patients (41%) experienced MACE during follow‐up. Patients who suffered MACE had an impaired resting and peak exercise systolic function in form of a lower LV ejection fraction (Rest: 56 ± 12% vs. 65 ± 7%, P < 0.001; Peak 64 ± 13% vs. 72 ± 6%, P < 0.01) and LVGLS (Rest: 13 ± 4% vs. 16 ± 2%, P < 0.01; Peak: 15 ± 6% vs. 20 ± 4%, P = 0.0001) than patients without MACE episodes. In contrast, resting diastolic filling patterns were comparable between patients suffering from MACE and patients without MACE.

At rest, pulmonary capillary wedge pressure (mPCWP) and cardiac index did not predict MACE, whereas increased right atrial pressure (mRAP) was associated with increased MACE risk. Patients with peak exercise mPCWP >23 mmHg [hazard ratio (HR) 2.5, 95% confidence interval (CI): 1.2–5.4], cardiac index <5.9 L/min/m² (HR 2.7, 95% CI: 1.0–6.3), or mRAP >13 mmHg (HR 2.7, 95% CI: 1.1–6.3) had increased MACE risk.

Patients with exercise‐induced LVGLS increase <3.5% and peak exercise cardiac index <5.9 L/min/m² [HR 6.1 (95% CI: 2.2–17.1)] or mPCWP >23 mmHg [HR 6.1 (95% CI: 2.1–17.5)] or mRAP >13 mmHg [HR 7.5 (95% CI: 2.3–23.9)] had the highest MACE risk.

Conclusions

Resting haemodynamic parameters were poor MACE predictors in long‐term HTx patients. In contrast, peak exercise mPCWP, mRAP, and CI were significant MACE predictors. LVGLS both at rest and during exercise were significant MACE predictors, and the combined model with peak exercise LVGLS and peak exercise mPCWP, mRAP, and CI clearly identified high‐risk HTx patients in relation cardiovascular endpoints independently of time since HTx.

Impact of gender on echocardiographic characteristics in heart transplant recipients

AIMS

Assessment following heart transplantation (HTx) is routinely performed using transthoracic echocardiography. Differences in long-term mortality following HTx related to donor-recipient matching have been reported, but effects of gender on cardiac size and function are not well studied. The aims of this study were to evaluate differences in echocardiographic characteristics of HTx recipients defined by gender.

METHODS AND RESULTS

The study prospectively enrolled 123 (n = 34 female) HTx recipients of which 23 recipients was donor-recipient gender mismatched. Patients were examined with 2-dimensional echocardiography using Philips iE33 ultrasound system. Data were analysed across strata based on recipient gender and gender mismatch. Male recipients had larger left ventricular (LV) mass, thicker septal wall (P<0·001) and larger absolute LV volumes (P<0·001). Mean LV ejection fraction (EF) was higher in females (P<0·05), but no differences in conventional parameters of right ventricular (RV) function were found. Ventricular strain was higher in females than in males: LV global longitudinal strain (P<0·01), RV global longitudinal strain (P<0·05) and RV lateral free wall (P<0·05). The male group receiving a female donor heart had comparable EF and strain parameters to the female group receiving a gender-matched heart.

CONCLUSION

We found that female recipient gender was associated with smaller chamber size, higher LV EF and better LV and RV longitudinal strain. Gender-mismatched male recipients appeared to exhibit function parameters similar to gender-matched female recipients. Our results indicate that the gender aspect, analogous to current reference guidelines in general population, should be taken into consideration when examining patients post-HTx.

Myocardial perfusion reserve and global longitudinal strain as potential markers of coronary allograft vasculopathy in late-stage orthotopic heart transplantation

Coronary allograft vasculopathy (CAV) is a major cause of mortality in late-stage orthotopic heart transplantation (OHT) patients. Recent evidence has shown that myocardial perfusion reserve (MPR) derived from vasodilator cardiovascular magnetic resonance imaging (vCMR) and global longitudinal strain (GLS) from transthoracic echocardiography (TTE) are useful to detect CAV. However, previous studies have not comprehensively addressed whether these parameters are confounded by allograft rejection, myocardial scar/fibrosis, or allograft dysfunction. Our aim was to determine whether changes in late post-OHT MPR and GLS are due to CAV or other confounding factors. Twenty OHT patients (time from transplant to vCMR was 8.1 ± 4.1 years) and 30 controls (10 healthy volunteers and 20 with prior myocardial infarction to provide perspective with regards to the severity of any abnormalities seen in post-OHT patients) underwent vasodilator vCMR from which MPR index (MPRi), left ventricular ejection fraction (LVEF), and burden of late gadolinium enhancement (LGE) were quantified. TTE was used to measure GLS. The presence of CAV was determined from invasive coronary angiograms using thrombolysis in myocardial infarction (TIMI) frame counts and grading severity per guidelines. Previous endomyocardial biopsies were reviewed to assess association with episodes of rejection. We examined the correlations between MPRi and GLS with markers of CAV, allograft function, scar/fibrosis, and rejection. MPRi was abnormal in post-OHT patients compared to both healthy volunteers and MI controls. While there was no relationship between MPRi or GLS and LVEF, episodes of rejection, or LGE burden, both MPRi and GLS were associated with TIMI frame counts and presence and severity of CAV. Additionally, MPRi correlated with GLS (R = 0.68, P = 0.0002). In conclusion, MPRi and GLS are abnormal in late-stage OHT and associated with CAV, but not related to allograft rejection, myocardial scar/fibrosis, or allograft dysfunction. Non-invasive monitoring of MPRi and GLS may be a useful strategy to detect CAV.

Changes in left ventricular strain parameters following pediatric heart transplantation

STE is increasingly utilized to assess strain in a variety of pathologies. Strain measurements have demonstrated utility following HTx and may aid in the detection of rejection and CAV. Strain parameters have not been well defined in the pediatric HTx population. This study aimed to describe strain in pediatric HTx recipients compared to controls and assess changes over time. All pediatric HTx recipients with available echocardiograms (2004-2015) without rejection or CAV were identified. Longitudinal and circumferential strain was measured at <1 month, 1 year, 3 years, and 5 years post-transplant and compared to controls. A total of 218 echocardiograms were analyzed in 79 HTx recipients. At <1 month post-transplant, there was a significant decrement in longitudinal strain (GLS -14.6 vs -19.2, P < .001) with concurrent augmentation of circumferential strain (GCS -27.3 vs -24.3, P = .005). By 1 year post-HTx, all strain parameters normalized and were not significantly different from the control population. In the absence of graft complications, strain parameters did not change up to 5 years post-transplant. Abnormal longitudinal strain parameters are present in the early post-HTx period with a compensatory increase in circumferential strain. These changes normalize by 1 year post-transplant and do not change over time in the absence of graft complications.

Long-term prognostic value of invasive and non-invasive measures early after heart transplantation

BACKGROUND

Invasively assessed coronary microvascular resistance early after heart transplantation predicts worse long-term outcome; however, little is known about the relationship between microvascular resistance, left ventricular function and outcomes in this setting.

METHODS

A total of 100 cardiac transplant recipients had fractional flow reserve (FFR) and the index of microcirculatory resistance (IMR) measured in the left anterior descending artery and echocardiographic assessment of left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) at 1 year after heart transplantation. The primary endpoint was the composite of death and retransplantation occurring beyond the first post-operative year.

RESULTS

The mean FFR, IMR, LVEF, and GLS values at 1 year were 0.87 ± 0.06, 21.3 ± 17.3, 60.4 ± 5.4%, and 14.2 ± 2.4%, respectively. FFR and IMR had no significant correlation with LVEF and GLS. During a mean follow-up of 6.7 ± 4.2 years, the primary endpoint occurred in 24 patients (24.0%). By ROC curve analysis, IMR = 19.3 and GLS = 13.3% were the best cutoff values for predicting death or retransplantation. Cumulative event-free survival was significantly lower in patients with higher IMR (log-rank p = 0.02) and lower GLS (log-rank p < 0.001). Cumulative event-free survival can be further stratified by the combination of IMR and GLS (long-rank p < 0.001). By multivariable Cox proportional hazards model, higher IMR and lower GLS were independently associated with long-term death or retransplantation (elevated IMR, hazard ratio = 2.50, p = 0.04 and reduced GLS, hazard ratio = 3.79, p = 0.003, respectively).

CONCLUSION

Invasively assessed IMR does not correlate with GLS at 1 year after heart transplantation. IMR and GLS determined at 1 year may be used as independent predictors of late death or retransplantation.

Worsening in Longitudinal Strain and Strain Rate Anticipates Development of Pediatric Transplant Coronary Artery Vasculopathy as Soon as One Year Following Transplant

Transplant coronary artery vasculopathy (TCAV) following orthotopic heart transplantation (OHT) continues to be the primary reason for late graft failure in children. The current gold standard of diagnosis of TCAV is coronary angiography with or without intravascular ultrasound. This study investigates the longitudinal use of speckle-tracking echocardiographic strain imaging as an early non-invasive marker to screen for development of TCAV. Echocardiograms from patients who underwent OHT between 2006 and 2010 at Children's Hospital Colorado (n = 50) were retrospectively assessed. Studies were evaluated at baseline (within a month of transplant), then at each annual clinical follow-up for peak longitudinal (LS) and circumferential (CS) strain, systolic strain rate, and diastolic strain rate using Siemens Velocity Vector Imaging software. Comparisons were made between subjects who did and did not develop TCAV. Mean time to TCAV diagnosis following OHT was 3.2 years (range 1-5.1 years). One year after transplant, significant differences were seen between groups in LS (non-TCAV mean -19.6%, TCAV mean -17.3%, p = 0.03) and longitudinal strain rate (non-TCAV mean -1.7%/s, TCAV mean -1.4%/s, p = 0.04). These differences persisted in subsequent years. Differences in LS preceded the catheterization-based diagnosis of TCAV in pediatric heart recipients and were noted as early as one year post transplant. Additionally, within-subject LS changes may have utility as a non-invasive screening tool to predict those patients at increased risk for development of TCAV.

Normal Reference Ranges for Transthoracic Echocardiography Following Heart Transplantation

BACKGROUND

Heart function following heart transplantation (HTx) is influenced by numerous factors. It is typically evaluated using transthoracic echocardiography, but reference values are currently unavailable for this context. The primary aim of the present study was to derive echocardiographic reference values for chamber size and function, including cardiac mechanics, in clinically stable HTx patients.

METHODS

The study enrolled 124 healthy HTx patients examined prospectively. Patients underwent comprehensive two-dimensional echocardiographic examinations according to contemporary guidelines. Results were compared with recognized reference values for healthy subjects.

RESULTS

Compared with guidelines, larger atrial dimensions were seen in HTx patients. Left ventricular (LV) diastolic volume was smaller, and LV wall thickness was increased. With respect to LV function, both ejection fraction (62 ± 7%, P < .01) and global longitudinal strain (-16.5 ± 3.3%, P < .0001) were lower. All measures of right ventricular (RV) size were greater than reference values (P < .0001), and all measures of RV function were reduced (tricuspid annular plane systolic excursion 15 ± 4 mm [P < .0001], RV systolic tissue Doppler velocity 10 ± 6 cm/sec [P < .0001], fractional area change 40 ± 8% [P < .0001], and RV free wall strain -16.9 ± 4.2% [P < .0001]). Ejection fraction and LV global longitudinal strain were significantly lower in patients with previous rejection.

CONCLUSION

The findings of this study indicate that the distribution of routinely used echocardiographic measures differs between stable HTx patients and healthy subjects. In particular, markedly larger RV and atrial volumes and mild reductions in both LV and RV longitudinal strain were evident. The observed differences could be clinically relevant in the assessment of HTx patients, and specific reference values should be applied in this context.

Prognostic Utility of Right Ventricular Free Wall Strain in Low Risk Patients After Orthotopic Heart Transplantation

Global longitudinal strain (GLS) by speckle-tracking echocardiography is a sensitive measure of regional left and right ventricular (LV and RV) dysfunction, before onset of overt systolic dysfunction. We sought to evaluate the prognostic utility of measuring LV-GLS and RV free wall strain (FWS) in low risk patients at 1 year after orthotopic heart transplantation (OHT). We retrospectively studied 96 OHT recipients (age 52 ± 14 years, 64% men) free of antibody-mediated rejection or moderate to severe coronary allograft vasculopathy (CAV, grade 2 to 3) at 1 year after transplant. LV-GLS and RV-FWS were calculated using EchoPAC software. Cox models were developed after adjusting for the Index for Mortality Prediction After Cardiac Transplantation (IMPACT) score (post-transplant risk score), with the primary outcome of death, moderate to severe CAV, or treated rejection. At 1 year after transplant, LV ejection fraction and RV fractional area change (FAC) were 58 ± 7% and 42 ± 10%, respectively. LV-GLS was -17.0 ± 3.3% and RV-FWS -16.4 ± 4.5%. At an average follow-up of 4.5 years, 28 patients met the primary end point (10 death, 5 vasculopathy, 17 rejection). In sequential Cox models, markers of RV function were associated with the primary outcome (RV-FAC, p = 0.012; RV-FWS, p = 0.022), while LV ejection fraction and LV-GLS were not. We conclude that in low risk patients 1 year after OHT, markers of RV function (RV-FAC and RV-FWS) are independently associated with incident rejection, CAV, and death. Markers of RV dysfunction could potentially be incorporated into risk scores and future prospective studies to risk stratify patients after OHT.

Transplant allograft vasculopathy: Role of multimodality imaging in surveillance and diagnosis

Cardiac allograft vasculopathy (CAV) is a challenging long-term complication of cardiac transplantation and remains a leading long-term cause of graft failure, re-transplantation, and death. CAV is an inflammatory vasculopathy distinct from traditional atherosclerotic coronary artery disease. Historically, the surveillance and diagnosis of CAV has been dependent on serial invasive coronary angiography with intravascular imaging. Although commonly practiced, angiography is not without significant limitations. Technological advances have provided sophisticated imaging techniques for CAV assessment. It is now possible to assess the vascular lumen, vessel wall characteristics, absolute blood flow, perfusion reserve, myocardial contractile function, and myocardial metabolism and injury in a noninvasive, expeditious manner with little risk. The current article will review key imaging modalities for the surveillance, diagnosis, and prognosis of CAV and discuss coronary physiology of transplanted hearts with emphasis on the clinical implications for provocative and vasodilator stress testing.

Noninvasive Detection of Cardiac Allograft Vasculopathy by Stress Exercise Echocardiographic Assessment of Myocardial Deformation

BACKGROUND

The aim of this study was to evaluate the value of noninvasive assessment of cardiac allograft vasculopathy (CAV) in heart-transplanted patients by exercise stress myocardial deformation and coronary flow reserve (CFR) assessment.

METHODS

Fifty-eight heart-transplanted patients underwent semisupine exercise echocardiography with assessment of left ventricular (LV) longitudinal myocardial deformation. CAV was assessed by coronary angiography and noninvasive CFR by (15)O-H2O positron emission tomographic imaging and Doppler echocardiography. Patients were divided into three groups on the basis of angiographic CAV: no CAV (n = 21), mild CAV (n = 19), and severe CAV (n = 18).

RESULTS

Patients with severe CAV had significantly lower LV global longitudinal strain (GLS) at rest (no CAV, -16 ± 2%; mild CAV, -15 ± 2%; severe CAV, -12 ± 4%; P < .001), failed to increase LV GLS during exercise (no CAV, -5.7 ± 2.0%; mild CAV, -3.3 ± 2.9%; severe CAV, -0.2 ± 2.8%; P < .0001), and had significantly lower echocardiographic coronary flow velocity reserve (CFVR) (no CAV, 3.2 ± 0.4; mild CAV, 2.7 ± 0.7; severe CAV, 1.8 ± 0.5; P < .0001) and PET CFR (no CAV, 3.4 ± 0.9; mild CAV, 3.1 ± 0.9; severe CAV, 1.9 ± 0.8; P < .0001). Furthermore, patients with mild CAV had significantly lower exercise LV GLS and echocardiographic CFVR than patients with no CAV. Exercise LV GLS, echocardiographic CFVR, and PET CFR were significantly correlated with the presence of severe CAV in a logistic regression model (LV GLS odds ratio, 0.71; 95% CI, 0.60-0.84; P < .0001; echocardiographic CFVR odds ratio: 0.06; 95% CI, 0.01-0.23; PET CFR odds ratio, 0.17; 95% CI, 0.07-0.46). This relation remained significant after adjustment for symptoms and time since transplantation.

CONCLUSIONS

Noninvasive assessment of LV longitudinal myocardial deformation during exercise is feasible and strongly associated with the presence and degree of CAV. Exercise stress myocardial deformation analysis, echocardiographic CFVR, or PET CFR may serve as a noninvasive model for the detection of CAV.

Coronary Flow Reserve Predicts Longitudinal Myocardial Deformation Capacity in Heart-Transplanted Patients

AIMS

This study aimed to evaluate the role of microvascular dysfunction on left ventricular (LV) longitudinal deformation, filling pressures, and exercise capacity in heart-transplanted (HTx) patients.

METHODS AND RESULTS

Fifty-seven HTx patients underwent comprehensive echocardiographic graft function assessment during symptom-limited, semisupine exercise test with simultaneous right heart catheterization. Coronary flow velocity reserve (CFVR) was measured in the left anterior descending artery using pulsed Doppler echocardiography. We divided patients into two groups based on upper and lower median of CFVR. Twenty-six healthy subjects served as controls. Compared with healthy controls, HTx patients had reduced CFVR (P < 0.0001), exercise capacity (P < 0.0001), and LV longitudinal deformation capacity (P < 0.0001). HTx patients in the reduced CFVR group (CFVR < 2.73) were more symptomatic (P < 0.0001) and had higher prevalence of coronary cardiac allograft vasculopathy (CAV) (P < 0.0001) than patients in the high CFVR group. Systolic function improved in both HTx groups during exercise. However, LV longitudinal myocardial deformation improved significantly more in the high CFVR group (P < 0.0001). Peak exercise LV global longitudinal strain and CFVR were strongly correlated (r = 0.8, P < 0.0001). A weak correlation was observed between CFVR and invasive cardiac index at peak exercise (r = 0.35, P < 0.01) and CFVR and LV filling measured by E/e' ratio (r = -0.41, P < 0.01) and pulmonary capillary wedge pressure (r = -0.30, P < 0.05).

CONCLUSION

HTx patients have reduced CFVR, exercise capacity, and LV longitudinal myocardial deformation capacity compared with healthy individuals. HTx patients with reduced CFVR are more symptomatic and have increased prevalence of CAV. Furthermore, reduced CFVR is correlated with reduced LV longitudinal myocardial deformation and exercise capacity.

Imaging in patients after cardiac transplantation and in patients with ventricular assist devices

The field of cardiac imaging and the management of patients with severe heart failure have advanced substantially during the past 10 years. Cardiac transplantation offers the best long-term survival with high quality of life for the patients with end stage heart failure. However, acute cardiac rejection and cardiac allograft vasculopathy (CAV) can occur post cardiac transplantation and these problems necessitate regular surveillance. The short-term success of mechanical circulatory support devices (MCSD), such as ventricular assist devices (VADs), in improving survival and quality of life has led to a dramatic growth of the patient population with these devices. The development of optimal imaging techniques and algorithms to evaluate these advanced heart failure patients is evolving and multimodality non-invasive imaging approaches and invasive techniques are commonly employed. Most of the published studies done in the transplant and VAD population are small, and biased based on the strength of the particular program, and there is a relative lack of published protocols to evaluate these patient groups. Moreover, the techniques of echocardiography, computed tomography (CT), magnetic resonance imaging, and nuclear cardiology have all progressed rapidly in recent years. There is thus a knowledge gap for cardiologists, radiologists, and clinicians, especially regarding surveillance for CAV and ideal imaging approaches for patients with VADs. The purpose of this review article is to provide an overview of different noninvasive imaging modalities used to evaluate patients after cardiac transplantation and for patients with VADs. The review focuses on the role of echocardiography, CT, and nuclear imaging in surveillance for CAV and rejection and on the assessment of ventricular structure and function, myocardial remodeling and complications for VAD patients.

Serial changes in longitudinal graft function and implications of acute cellular graft rejections during the first year after heart transplantation

AIMS

The aim of this prospective study was to use left ventricular global longitudinal strain (LV-GLS) as a non-invasive tool for the monitoring of graft function in relation to acute cellular rejection (ACR) during the first year after heart transplantation (HTX).

METHODS AND RESULTS

The study population consisted of 36 patients undergoing HTX from November 2010 until October 2013. Patients were followed by comprehensive echocardiography and biopsies at 2 weeks and 1, 3, 6, and 12 months after HTX. ACRs were classified based on the ISHLT classification (0R-3R). Patients were divided into two groups according to the presence of one or more episodes of biopsy proven ≥grade 2R ACR during follow-up. We found that LV-GLS and tricuspid annular plane systolic excursion (TAPSE) were significantly related to ACR burden in a linear regression model. The absolute difference in LV-GLS between patients in the ACR group (-14.4%) and patients in the ACR-free group (-16.8%) was -2.4% (P < 0.01) 12 months after HTX. In the ACR group, patients' LV-GLS did not improve between 1 and 12 months, whereas an improvement of -2.9% was seen in the ACR-free group in this period (P < 0.01). The two groups appeared not to differ in terms of diastolic Doppler parameters or LV ejection fraction, but TAPSE was 15.3 ± 2.8 mm in the ACR-free group vs. 13.2 ± 2.1 mm ACR group, P < 0.05, 12 months after HTX.

CONCLUSION

Gradual improvement of longitudinal LV and RV function was seen within the first year after HTX, but the degree of recovery was strongly influenced by ACR episodes.