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

Early left ventricular systolic function is a more sensitive predictor of adverse events after heart transplant

BACKGROUND

First-phase ejection fraction (EF1) is a novel measure of early changes in left ventricular systolic function. This study was to investigate the prognostic value of EF1 in heart transplant recipients.

METHODS

Heart transplant recipients were prospectively recruited at the Union Hospital, Wuhan, China between January 2015 and December 2019. All patients underwent clinical examination, biochemistry measures [brain natriuretic peptide (BNP) and creatinine] and transthoracic echocardiography. The primary endpoint was a combined event of all-cause mortality and graft rejection.

RESULTS

In 277 patients (aged 48.6 ± 12.5 years) followed for a median of 38.7 [26.8-45.0] months, there were 35 (12.6%) patients had adverse events including 20 deaths and 15 rejections. EF1 was negatively associated with BNP (β = -0.220, p < 0.001) and was significantly lower in patients with events compared to those without. EF1 had the largest area under the curve in ROC analysis compared to other measures. An optimal cut-off value of 25.8% for EF1 had a sensitivity of 96.3% and a specificity of 97.1% for prediction of events. EF1 was the most powerful predictor of events with hazard ratio per 1% change in EF1: 0.628 (95%CI: 0.555-0.710, p < 0.001) after adjustment for left ventricular ejection fraction and global longitudinal strain.

CONCLUSIONS

Early left ventricular systolic function as measured by EF1 is a powerful predictor of adverse outcomes after heart transplant. EF1 may be useful in risk stratification and management of heart transplant recipients.

Multimodality Imaging to Detect Rejection, and Cardiac Allograft Vasculopathy in Pediatric Heart Transplant Recipients—An Illustrative Review

The three most common modalities of graft surveillance in pediatric heart transplant (HT) recipients include echocardiography, coronary angiography, and endomyocardial biopsy (EMB). The survival outcomes after HT in children have improved considerably in recent years. However, allograft rejection and cardiac allograft vasculopathy remain the leading cause of death or re-transplantation. The routine surveillance by EMB and coronary angiography are invasive and risky. Newer noninvasive echocardiographic techniques, including tissue Doppler imaging (TDI), 2-D speckle tracking echocardiography, CT coronary angiography (CTCA), cardiovascular magnetic resonance (CMR), single-photon emission computed tomography (SPECT), and positron emission tomography (PET) and invasive techniques such as intravascular ultrasound (IVUS), functional flow reserve (CFR) of coronary arteries, optical coherence tomography (OCT), have emerged as powerful tools which may help early recognition of sub-clinical rejection, response to treatment, early detection, and progression of CAV. The multimodality imaging approach, including noninvasive and invasive tests, is the future for the transplanted heart to detect dysfunction, rejections, and early CAV. This review illustrates noninvasive and invasive imaging techniques currently used or could be considered for clinical use in detecting heart transplant rejection, dysfunction, and CAV in children.

Cardiopulmonary transit time: A novel PET imaging biomarker of in vivo physiology for risk stratification of heart transplant recipients

BACKGROUND

Myocardial blood flow (MBF) can be quantified using dynamic PET studies. These studies also inherently contain tomographic images of early bolus displacement, which can provide cardiopulmonary transit times (CPTT) as measure of cardiopulmonary physiology. The aim of this study was to assess the incremental prognostic value of CPTT in heart transplant (OHT) recipients.

METHODS

94 patients (age 56 ± 16 years, 78% male) undergoing dynamic 13N-ammonia stress/rest studies were included, of which 68 underwent right-heart catherization. A recently validated cardiac allograft vasculopathy (CAV) score based on PET measures of regional perfusion, peak MBF and left-ventricular (LV) ejection fraction (LVEF) was used to identify patients with no, mild or moderate-severe CAV. Time-activity curves of the LV and right ventricular (RV) cavities were obtained and used to calculate the difference between the LV and RV bolus midpoint times, which represents the CPTT and is expressed in heartbeats. Patients were followed for a median of 2.5 years for the occurrence of major adverse cardiac events (MACE), including cardiovascular death, hospitalization for heart failure or acute coronary syndrome, or re-transplantation.

RESULTS

CPTT was significantly correlated with cardiac filling pressures (r = .434, P = .0002 and r = .439, P = .0002 for right atrial and pulmonary wedge pressure), cardiac output (r = - .315, P = .01) and LVEF (r = - .513, P < .0001). CPTT was prolonged in patients with MACE (19.4 ± 6.0 vs 14.5 ± 3.0 heartbeats, P < .001, N = 15) with CPTT ≥ 17.75 beats showing optimal discriminatory value in ROC analysis. CPTT ≥ 17.75 heartbeats was associated with a 10.1-fold increased risk (P < .001) of MACE and a 7.3-fold increased risk (P < .001) after adjusting for PET-CAV, age, sex and time since transplant.

CONCLUSION

Measurements of cardiopulmonary transit time provide incremental risk stratification in OHT recipients and enhance the value of multiparametric dynamic PET imaging, particularly in identifying high-risk patients.

Cardiac allograft vasculopathy: A review

BACKGROUND

Heart transplantation has become the standard of care for pediatric patients with end-stage heart disease, and outcomes have consistently improved over the last few decades. CAV, however, remains a leading cause of morbidity and mortality in heart transplantation and is the leading cause of death beyond 3 years post-transplantation. We sought out to provide an in-depth overview of CAV in the pediatric heart transplant population.

METHODS

Database searches were conducted in both Medline and Embase on the topic of cardiac vasculopathy in pediatric heart transplant recipients. The search used five broad concept terms: heart transplant; pediatric; CAV; diagnosis, prognosis, and risk factors; and guidelines and reviews. References were captured if there was at least one term in each of the concepts. The search was limited to articles in the English language.

RESULTS

A total of 148 articles were identified via the literature search with further articles identified via review of references. Pediatric data regarding the etiology and development of CAV remain limited although knowledge about the immune and non-immune factors playing a role are increasing. CAV continues to be difficult to detect with many invasive and non-invasive methods available, yet their effectiveness in the detection of CAV remains suboptimal. There remains no proven medical intervention to treat or reverse established CAV disease, and CAV is associated with high rates of graft loss once detected. However, several medications are used in hopes of preventing, slowing progression, or modifying the outcomes.

CONCLUSION

This review provides a comprehensive overview of CAV, discusses its clinical presentation, risk factors, diagnostic tools used to identify CAV in the pediatric population, and highlights the current therapeutic options and the need for ongoing research.

Clinical Utility of SPECT in the Heart Transplant Population: Analysis From a Single Large-volume Center

BACKGROUND

Survival after heart transplant has greatly improved, with median survival now over 12 years. Cardiac allograft vasculopathy (CAV) has become a major source of long-term morbidity and mortality. Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is used for CAV surveillance, but there is limited data on its prognostic utility.

METHODS

We retrospectively identified patients undergoing SPECT MPI for CAV surveillance at a single, large-volume center. Images were assessed with semiquantitative visual scoring (summed stress score [SSS] and summed rest score) and quantitatively with total perfusion defect (TPD).

RESULTS

We studied 503 patients (mean age 62.5, 69.3% male) at a median of 9.0 years post-transplant. During mean follow-up of 5.1 ± 2.5 years, 114 (22.6%) patients died. The diagnostic accuracy for significant CAV (ISHLT grade 2 or 3) was highest for SSS with an area under the curve of 0.650 and stress TPD (area under the curve, 0.648), with no significant difference between SSS and stress TPD (P = 0.061). Stress TPD (adjusted hazard ratio, 1.07; P = 0.018) was independently associated with all-cause mortality, while SSS was not (P = 0.064). The prognostic accuracy of quantitative assessment of perfusion tended to be higher compared with semiquantitative assessment, with the highest accuracy for stress TPD (area under the receiver operating curve 0.584).

CONCLUSIONS

While SPECT MPI identified a cohort of higher risk patients, with quantitative analysis of perfusion demonstrating higher prognostic accuracy. However, the overall prognostic accuracy was modest and alternative noninvasive modalities may be more suitable for CAV surveillance.

Non-Invasive Imaging in the Evaluation of Cardiac Allograft Vasculopathy in Heart Transplantation: A Systematic Review

Cardiac allograft vasculopathy (CAV) is the leading cause of long-term graft dysfunction in patients with heart transplantation and is linked with significant morbidity and mortality. Currently, the gold standard for diagnosing CAV is coronary imaging with intravascular ultrasound (IVUS) during traditional invasive coronary angiography (ICA). Invasive imaging, however, carries increased procedural risk and expense to patients in addition to requiring an experienced interventionalist. With the improvements in non-invasive cardiac imaging modalities such as transthoracic echocardiography (TTE), computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET), an alternative non-invasive imaging approach for the early detection of CAV may be feasible. In this systematic review, we explored the literature to investigate the utility of non-invasive imaging in diagnosis of CAV in >3000 patients across 49 studies. We also discuss the strengths and weaknesses for each imaging modality. Overall, all four imaging modalities show good to excellent accuracy for identifying CAV with significant variations across studies. Majority of the studies compared non-invasive imaging with ICA without intravascular imaging. In summary, non-invasive imaging modalities offer an alternative approach to invasive coronary imaging for CAV. Future studies should investigate longitudinal non-invasive protocols in low-risk patients after heart transplantation.

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 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.

Right ventricular hemodynamics and performance in relation to perfusion during first year after heart transplantation

Aims

We aim to evaluate changes in invasive haemodynamics, right ventricular (RV) function, and perfusion during the first year after heart transplantation (HTx) and to determine the relation between RV function and myocardial perfusion.

Methods and results

Thirty patients were prospectively enrolled at the time of HTx. Right heart catheterization (RHC), comprehensive 2D and 3D echocardiography and cardiac biomarkers were performed at baseline (≤2 weeks after HTx) and at follow‐up 1, 3, 6, and 12 months after HTx. At 12 months, HTx patients were subjected to an exercise stress test with assessment of maximal oxygen consumption (VO₂max). RV myocardial perfusion reserve was evaluated by ¹⁵O‐H₂O positron emission tomography at baseline and at 3 and 12 months after HTx. A group of 43 healthy subjects served as echocardiographic controls and a subgroup comprising 16 healthy controls underwent exercise stress test with simultaneous RHC. At baseline, HTx patients had higher pulmonary artery wedge pressure (PAWP) and right atrial pressure (RAP) and pulmonary vascular resistance (PVR) than healthy controls whereas cardiac index (CI) was reduced (PAWP; 14 mmHg [8;17] vs. 8 mmHg [7;10]; RAP: 7 mmHg [4;11] vs. 5 mmHg [4;6]; PVR: 1.9 wood units [1.3;2.6] vs. 1.1 wood units [1.0;1.4]; CI 2.4 L/min/m² [2.2;2.8] vs. 3.3 L/min/m² [2.8;.3.6], all P < 0.05). Normalization of filling pressures and CI was seen 3–6 months after HTx. During follow‐up, RV function in terms of 3D ejection fraction (EF) and longitudinal strain (LS) improved in HTx patients but remained reduced compared with healthy controls at 12 months follow‐up (3D RV EF: 52 ± 7% vs. 60 ± 8%; RV LS: 22 ± 4% vs. 28 ± 5%, both P < 0.001). During follow‐up, RV perfusion reserve improved (baseline 2.1 ± 0.9; 3 months follow‐up 3.2 ± 0.8; 12 months follow‐up 3.7 ± 1.1, P < 0.0001). RV perfusion reserve significantly correlated to cardiac markers in terms of troponin T (r = −0.62, P < 0.0001), NT‐proBNP (r = −0.65, P < 0.0001), RAP (r = −0.43, P < 0.01) and CI (r = 0.37, P < 0.01) and with VO₂max 12 months after HTx (r = 0.75, P < 0.01).

Conclusions

Normalization of left and right atrial filling pressures is demonstrated within the first 3 to 6 months after HTx. RV function and RV perfusion reserve correlated and gradually improved during the first year after HTx but RV function remained reduced in HTx patients compared with healthy controls.

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.

Micro- and macrovascular cardiac allograft vasculopathy in relation to 91 cardiovascular biomarkers in heart transplant recipients-An exploratory study

BACKGROUND

Cardiac allograft vasculopathy (CAV) limits survival after heart transplantation (HTx), and the pathogenesis is not fully clarified. We aimed to investigate a wide range of biomarkers and their correlation with micro- and macrovascular CAV and major adverse cardiac events in HTx patients.

METHODS

We evaluated 91 cardiovascular disease-related proteins in 48 HTx patients using a novel proteomic panel. Patients were dichotomized according to micro- and macrovascular CAV burden determined by coronary angiography, optical coherence tomography, and ¹⁵ O-H₂ O positron emission tomography imaging. Major adverse cardiac events included significant CAV progression, heart failure, treated rejection, and cardiovascular death.

RESULTS

We found consistent differences in two proteins involved in cholesterol homeostasis: significantly increased proprotein convertase subtilisin/kexin type 9 (PCSK9) (p < .05) and significantly decreased paraoxonase 3 (PON3) (p < .05). N-terminal pro-brain natriuretic peptide (NT-proBNP) was significantly increased in patients with microvascular CAV (p < .05) and borderline significantly increased in patients experiencing major adverse cardiac events (p = .10) and patients with macrovascular CAV (p = .05).

CONCLUSIONS

We identified consistent changes in two proteins involved in cholesterol homeostasis which may be important players in the pathogenesis of CAV: PON3 and PCSK9. NT-proBNP also showed consistent changes across all groups but only reached statistical significance in patients with microvascular CAV. Our results warrant further validation in future studies.

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.

The Utility of Cardiac Reserve for the Early Detection of Cancer Treatment-Related Cardiac Dysfunction: A Comprehensive Overview

With progressive advancements in cancer detection and treatment, cancer-specific survival has improved dramatically over the past decades. Consequently, long-term health outcomes are increasingly defined by comorbidities such as cardiovascular disease. Importantly, a number of well-established and emerging cancer treatments have been associated with varying degrees of cardiovascular injury that may not emerge until years following the completion of cancer treatment. Of particular concern is the development of cancer treatment related cardiac dysfunction (CTRCD) which is associated with an increased risk of heart failure and high risk of morbidity and mortality. Early detection of CTRCD appears critical for preventing long-term cardiovascular morbidity in cancer survivors. However, current clinical standards for the identification of CTRCD rely on assessments of cardiac function in the resting state. This provides incomplete information about the heart's reserve capacity and may reduce the sensitivity for detecting sub-clinical myocardial injury. Advances in non-invasive imaging techniques have enabled cardiac function to be quantified during exercise thereby providing a novel means of identifying early cardiac dysfunction that has proved useful in several cardiovascular pathologies. The purpose of this narrative review is (1) to discuss the different non-invasive imaging techniques that can be used for quantifying different aspects of cardiac reserve; (2) discuss the findings from studies of cancer patients that have measured cardiac reserve as a marker of CTRCD; and (3) highlight the future directions important knowledge gaps that need to be addressed for cardiac reserve to be effectively integrated into routine monitoring for cancer patients exposed to cardiotoxic therapies.

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.

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.

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.