Diagnosis and management of cardiac allograft vasculopathy

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.

Randomized Trial of Cholesterol Lowering With Evolocumab for Cardiac Allograft Vasculopathy in Heart Transplant Recipients

BACKGROUND

Cardiac allograft vasculopathy is characterized by increased coronary intimal thickness and is a leading cause of death in heart transplant (HTx) recipients despite the routine use of statins. The experience with inhibitors of proprotein convertase subtilisin-kexin type 9 in HTx recipients is limited. Our hypothesis was that lowering cholesterol with the proprotein convertase subtilisin-kexin type 9inhibitor evolocumab would reduce coronary intimal thickness in these patients without compromising safety.

OBJECTIVES

This double blind, randomized trial was conducted to test whether evolocumab reduces the burden of cardiac allograft vasculopathy.

METHODS

Patients who had received a cardiac allograft at 1 of the Nordic transplant centers within the prior 4 to 8 weeks were randomized to monthly subcutaneous injections of evolocumab 420 mg or matching placebo. The primary endpoint was the baseline-adjusted maximal intimal thickness as measured by intracoronary ultrasound after 12 months' treatment.

RESULTS

The trial enrolled 128 patients between June 2019 and May 2022. Matched pairs of coronary ultrasound images were available for 56 patients assigned to evolocumab and 54 patients assigned to placebo. At 12 months, the adjusted mean difference in the maximal intimal thickness between the 2 arms was 0.017 mm (95% CI: -0.006 to 0.040; P = 0.14). The mean reduction in low-density lipoprotein cholesterol with evolocumab compared with placebo was 1.11 mmol/L (95% CI: 0.86-1.37 mmol/L). The use of evolocumab was not associated with an increase in adverse events.

CONCLUSIONS

Twelve months of treatment with evolocumab substantially reduced low-density lipoprotein cholesterol but did not reduce maximal coronary intimal thickness in HTx recipients. (Cholesterol Lowering With EVOLocumab to Prevent Cardiac Allograft Vasculopathy in De-novo Heart Transplant Recipients [EVOLVD]; NCT03734211).

Redefining CAV surveillance strategies: Benefits of CCTA vs. ICA

BACKGROUND

Cardiac allograft vasculopathy (CAV) assessment post-heart transplantation (HT) typically relies on invasive coronary angiography (ICA). However, cardiac computed tomography angiography (CCTA) is emerging as a promising alternative due to its potential benefits in economic, safety, and logistical aspects. This study aimed to evaluate the impact of a CCTA program on these aspects in CAV surveillance post-HT.

METHODS

A retrospective single-center study was conducted between March 2021 and February 2023, involving HT patients who underwent either CCTA or ICA.

RESULTS

Among 260 patients undergoing CAV surveillance, 115 (44.2%) patients underwent CCTA, and 145 (55.8%) patients underwent ICA. The CCTA group showed incurred lower overall costs (p ​< ​0.0001) and shorter hospitalization times (p ​< ​0.0001) compared to the ICA group. In terms of safety, CCTA surveillance required significantly lower contrast volumes (p ​< ​0.0001) and lower effective doses (p ​= ​0.03).

CONCLUSION

CCTA emerges as a safe and cost-effective non-invasive alternative for CAV surveillance post-HT, outperforming ICA in terms of safety, logistical aspects, and economic burden.

Computed tomography pericoronary adipose tissue density predicts coronary allograft vasculopathy and adverse clinical outcomes after cardiac transplantation

AIMS

To assess pericoronary adipose tissue (PCAT) density on coronary computed tomography angiography (CCTA) as a marker of inflammatory disease activity in coronary allograft vasculopathy (CAV).

METHODS AND RESULTS

PCAT density, lesion volumes, and total vessel volume-to-myocardial mass ratio (V/M) were retrospectively measured in 126 CCTAs from 94 heart transplant patients [mean age 49 (SD 14.5) years, 40% female] who underwent imaging between 2010 and 2021; age- and sex-matched controls; and patients with atherosclerosis. PCAT density was higher in transplant patients with CAV [n = 40; -73.0 HU (SD 9.3)] than without CAV [n = 86; -77.9 HU (SD 8.2)], and controls [n = 12; -86.2 HU (SD 5.4)], P < 0.01 for both. Unlike patients with atherosclerotic coronary artery disease (n = 32), CAV lesions were predominantly non-calcified and comprised of mostly fibrous or fibrofatty tissue. V/M was lower in patients with CAV than without [32.4 mm3/g (SD 9.7) vs. 41.4 mm3/g (SD 12.3), P < 0.0001]. PCAT density and V/M improved the ability to predict CAV from area under the receiver operating characteristic curve (AUC) 0.75-0.85 when added to donor age and donor hypertension status (P < 0.0001). PCAT density above -66 HU was associated with a greater incidence of all-cause mortality {odds ratio [OR] 18.0 [95% confidence interval (CI) 3.25-99.6], P < 0.01} and the composite endpoint of death, CAV progression, acute rejection, and coronary revascularization [OR 7.47 (95% CI 1.8-31.6), P = 0.01] over 5.3 (SD 2.1) years.

CONCLUSION

Heart transplant patients with CAV have higher PCAT density and lower V/M than those without. Increased PCAT density is associated with adverse clinical outcomes. These CCTA metrics could be useful for the diagnosis and monitoring of CAV severity.

Transplant Vasculopathy Versus Native Atherosclerosis: Similarities and Differences

Cardiac allograft vasculopathy (CAV) is one of the leading causes of graft failure and death after heart transplantation. Alloimmune-dependent and -independent factors trigger the pathogenesis of CAV through activation of the recipients' (and to a lesser extent donor-derived) immune system. Early diagnosis of CAV is complicated by the lack of clinical symptoms for ischemia in the denervated heart, by the impact of early functional coronary alterations, by the insensitivity of coronary angiography, and by the involvement of small intramyocardial vessels. CAV in general is a panarterial disease confined to the allograft and characterized by diffuse concentric longitudinal intimal hyperplasia in the epicardial coronary arteries and concentric medial disease in the microvasculature. Plaque composition in CAV may include early fibrous and fibrofatty tissue and late atheromatous calcification. In contrast, native coronary atherosclerosis usually develops over decades, is focal, noncircumferential, and typically diminishes proximal parts of the epicardial vessels. The rapid and early development of CAV has an adverse prognostic impact, and current prevention and treatment strategies are of limited efficacy compared with established strategies in native atherosclerosis. Following acute coronary syndromes, patients after heart transplantation were more likely to have accompanying cardiogenic shock and higher mortality compared with acute coronary syndromes patients with native hearts.

Quantitative flow ratio computed from invasive coronary angiography as a predictor for cardiac allograft vasculopathy after cardiac transplant

Cardiac allograft vasculopathy (CAV) is a significant determinant of long-term survival in heart transplant recipients. Standard CAV screening typically utilizes invasive coronary angiography (ICA). Quantitative flow ratio (QFR) is a computational method for functional testing of coronary stenosis, and may add diagnostic value to ICA in assessing CAV. Consecutive subjects who received heart transplantation and underwent two separate routine coronary angiograms between January 2013 and April 2016 were enrolled. Coronary angiograms and IVUS were performed per local protocol at 1, 2, 3 and 5 years post-transplant. QFR was calculated offline. CAV was assessed semi-quantitively based on coronary angiogram results. Twenty-two patients were enrolled. Mean time from transplant to first included ICA was 2.1 years. QFR in at least 1 coronary vessel was interpretable in 19/22 (86%) of initial ICA (QFR1). QFR1 correlated well with the CAV score derived from the second ICA (CAV2) with a clustering of CAV at lower QFR values. In a receiver-operating characteristic (ROC) analysis, an optimal QFR threshold of 0.88 yielded 0.94 sensitivity and 0.67 specificity (AUC of 0.79) for at least non-obstructive subsequent CAV. Initial angiographically and intravascular ultrasound derived CAV severity poorly predicted subsequent CAV severity. QFR derived from invasive coronary angiography predicts subsequent development of CAV more accurately than angiography and intravascular ultrasound. This novel method of coronary flow assessment in recipients of heart transplantation may be useful to diagnose and predict subsequent CAV development.

Frequency, Risk Factors, and Clinical Outcomes of Late-Onset Atrial Flutter in Patients after Heart Transplantation

Aims: Atrial flutter (AFL) is a common late-onset complication after heart transplantation (HTX) and is associated with worse clinical outcomes. Methods: This study investigated the frequency, risk factors, and outcomes of late-onset post-transplant AFL. We analyzed 639 adult patients undergoing HTX at the Heidelberg Heart Center between 1989 and 2019. Patients were stratified by diagnosis and type of late-onset post-transplant AFL (>90 days after HTX). Results: A total of 55 patients (8.6%) were diagnosed with late-onset post-transplant AFL, 30 had typical AFL (54.5%) and 25 had atypical AFL (45.5%). Patients with AFL were younger at HTX (p = 0.028), received more biatrial anastomosis (p = 0.001), and presented with moderate or severe tricuspid regurgitation (56.4%). Typical AFL was associated with graft rejection (p = 0.016), whereas atypical AFL was associated with coronary artery disease (p = 0.028) and stent implantation (p = 0.042). Patients with atypical AFL showed a higher all-cause 1-year mortality (p = 0.010) along with a higher rate of graft failure after diagnosis of AFL (p = 0.023). Recurrence of AFL was high (83.6%). Patients with catheter ablation after AFL recurrence had a higher 1-year freedom from AFL (p = 0.003). Conclusions: Patients with late-onset post-transplant AFL were younger at HTX, received more biatrial anastomosis, and showed a higher rate of moderate or severe tricuspid regurgitation. Typical AFL was associated with graft rejection, whereas atypical AFL was associated with myocardial ischemia, graft failure, and mortality. Catheter ablation represents a viable option to avoid further episodes of late-onset AFL after HTX.

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.

Risk Factors, Treatment and Prognosis of Patients with Lung Cancer after Heart Transplantation

Long-term survival after heart transplantation (HTX) is impacted by adverse effects of immunosuppressive pharmacotherapy, and post-transplant lung cancer is a common occurrence. This study aimed to examine the risk factors, treatment, and prognosis of patients with post-transplant lung cancer. We included 625 adult patients who received HTX at Heidelberg Heart Center between 1989 and 2018. Patients were stratified by diagnosis and staging of lung cancer after HTX. Analysis comprised donor and recipient characteristics, medications including immunosuppressive drugs, and survival after diagnosis of lung cancer. A total of 41 patients (6.6%) were diagnosed with lung cancer after HTX, 13 patients received curative care and 28 patients had palliative care. Mean time from HTX until diagnosis of lung cancer was 8.6 ± 4.0 years and 1.8 ± 2.7 years from diagnosis of lung cancer until last follow-up. Twenty-four patients (58.5%) were switched to an mTOR-inhibitor after diagnosis of lung cancer. Multivariate analysis showed recipient age (HR: 1.05; CI: 1.01-1.10; p = 0.02), COPD (HR: 3.72; CI: 1.88-7.37; p < 0.01), and history of smoking (HR: 20.39; CI: 2.73-152.13; p < 0.01) as risk factors for post-transplant lung cancer. Patients in stages I and II had a significantly better 1-year (100.0% versus 3.6%), 2-year (69.2% versus 0.0%), and 5-year survival (53.8% versus 0.0%) than patients in stages III and IV (p < 0.01). Given the poor prognosis of late-stage post-transplant lung cancer, routine reassessment of current smoking status, providing smoking cessation support, and intensified lung cancer screening in high-risk HTX recipients are advisable.