Coronary Collateral Circulation: A New Predictor of Mortality in Heart Transplant Recipients With Allograft Vasculopathy.

Coronary collateral arteries (CCAs) are anastomotic channels between vessels; although beneficial in atherosclerosis, their role in heart transplantation (HT) recipients is underinvestigated. CCAs initially develop as microcirculation and cardiac allograft vasculopathy (CAV), promoting immune-dependent proliferative angiogenic response, and play a role in their development. In our hypothesis, ischemia induced by coronary microvascular dysfunction (CMD) triggers the development of CCAs, which are, in turn, less functional as affected by CAV themselves. Methods: One hundred twenty-one patients receiving HT at our institution were retrospectively evaluated and were included if transthoracic echocardiography with coronary flow velocity reserve (CFVR) assessment and coronary angiography were performed. CMD was defined as CFVR of ≤2.5. Patients with CAV were enrolled, and their angiograms were reviewed to evaluate the presence of CCAs. Cardiovascular mortality was assessed as the main clinical outcome. Results: Forty patients were found to have CCAs. Patients with CCAs have lower CFVR than those without CCAs (2.22 ± 0.72 versus 2.69 ± 0.92;P = 0.003), reflecting in different rates of CMD in the 2 groups (72.5% versus 37%; P < 0.001). CMD is associated with higher CAV grades (P < 0.001), which are also associated with CCAs (P < 0.001). Patients with poorly developed CCAs have lower CFVR (P < 0.001). At multivariable analysis, CMD (P = 0.008) and higher CAV grades (P = 0.005) are independent predictors of CCAs. During the median follow-up time of 10.2 (6.6-13.3) y, patients with CCAs have been found to have higher mortality than those without CCAs (57.5% versus 32.1%; P = 0.007). CCAs are associated with a lower probability of survival also in patients with CMD (P < 0.001) and are independent predictors of mortality (P < 0.001). Conclusions: Our results demonstrate an interplay between CAV, CMD, and CCAs. We confirm that CAV is associated with CMD, and we show, for the first time, that CMD is associated with CCAs. CCAs are pathophysiologically associated with more severe graft vasculopathy and independently predict mortality after HT.

Coronary Flow Evaluation in Heart Transplant Patients Compared to Healthy Controls Documents the Superiority of Coronary Flow Velocity Reserve Companion as Diagnostic and Prognostic Tool.

Background: Distinct contributions by functional or structural alterations of coronary microcirculation in heart transplantation (HT) and their prognostic role have not been fully elucidated. We aimed to identify the mechanisms of coronary microvascular dysfunction (CMD) in HT and their prognostic implications. Methods: 134 patients, surviving at least 5 years after HT, without evidence of angiographic vasculopathy or symptoms/signs of rejection were included. 50 healthy volunteers served as controls. All underwent the assessment of rest and hyperemic coronary diastolic peak flow velocity (DPVr and DPVh) and coronary flow velocity reserve (CFVR) and its inherent companion that is based on the adjusted quadratic mean: CCFVR = √{(DPVr)2 + (DPVh)2}. Additionally, basal and hyperemic coronary microvascular resistance (BMR and HMR) were estimated. Results: Based on CFVR and DPVh, HT patients can be assigned to four endotypes: endotype 1, discordant with preserved CFVR (3.1 ± 0.4); endotype 2, concordant with preserved CFVR (3.4 ± 0.5); endotype 3, concordant with impaired CFVR (1.8 ± 0.3) and endotype 4, discordant with impaired CFVR (2.0 ± 0.2). Intriguingly, endotype 1 showed lower DPVr (p < 0.0001) and lower DPVh (p < 0.0001) than controls with lower CFVR (p < 0.0001) and lower CCFVR (p < 0.0001) than controls. Moreover, both BMR and HMR were higher in endotype 1 than in controls (p = 0.001 and p < 0.0001, respectively), suggesting structural microvascular remodeling. Conversely, endotype 2 was comparable to controls. A 13/32 (41%) patients in endotype 1 died in a follow up of 28 years and mortality rate was comparable to endotype 3 (14/31, 45%). However, CCFVR was < 80 cm/s in all 13 deaths of endotype 1 (characterized by preserved CFVR). At multivariable analysis, CMD, DPVh < 75 cm/s and CCFVR < 80 cm/s were independent predictors of mortality. The inclusion of CCFVR < 80 cm/s to models with clinical indicators of mortality better predicted survival, compared to only adding CMD or DPVh < 75 cm/s (p < 0.0001 and p = 0.03, respectively). Conclusion: A normal CFVR could hide detection of microvasculopathy with high flow resistance and low flow velocities at rest. This microvasculopathy seems to be secondary to factors unrelated to HT (less rejections and more often diabetes). The combined use of CFVR and CCFVR provides more complete clinical and prognostic information on coronary microvasculopathy in HT.

Atrial fibrillation after orthotopic heart transplantatation: Pathophysiology and clinical impact.

BACKGROUND: Atrial fibrillation (AF) is a well-established post-cardiac surgery complication. Orthotopic heart transplantation (OHT) represents a peculiar condition where surgical thoracic veins isolation and autonomic denervation occur. This study aims at investigating AF incidence in OHT in order to define its risk factors and to evaluate its prognostic impact. METHODS: 278 patients affected by OHT were recruited in our Cardiac Surgery Unit and retrospectively analyzed, using clinical, surgical and instrumental data. RESULTS: The patients cohort showed 45 post-operative (16.5%) and 20 late AF cases (7.2%). Only paroxysmal AF episodes were observed. Elderly donors and acute rejection resulted as risk factors in patients with post-operative AF episodes, who presented higher all-cause mortality at 11 years post-OHT (p < 0.001, Kaplan Meier analysis). The majority of late AF episodes occurred during hospitalization, due to renal failure or infections and more frequently in male patients; no significant correlation was observed with acute or chronic rejection or other characteristics. CONCLUSION: Pulmonary vein isolation and vagal denervation lead to low AF incidence in OHT recipients. Acute rejection and graft status are the main risk factors for post-operative AF episodes, while other systemic conditions act as late AF triggers. The occurrence of AF episodes is associated with poor outcome and AF should be considered as a marker of clinical frailty.

Coronavirus disease 2019 (COVID-19) in the heart transplant population: a single-centre experience.

OBJECTIVES: Few anecdotal cases have been reported in the literature regarding heart transplant recipients and infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We report our experience with 6 patients hospitalized in Northern Italy during the outbreak. METHODS: Of the 396 living heart transplant recipients from 1985 to 2020 included in the study, 6 patients developed the novel 2019 coronavirus disease. Risk factors, last follow-up characteristics, onset presentation, in-hospital course of disease and blood examinations data were collected for these patients. RESULTS: All patients were symptomatic and had positive results from a nasopharyngeal swab test for SARS-CoV-2. Of the 6 patients, 5 were hospitalized and 1 remained self-quarantined at home. Two patients died and 3 were discharged home. Two patients were admittted to the intensive care unit . Immunosuppressive therapy was modified with a median reduction comprising doses that were 50% cyclosporine and 50% mycophenolate. All patients received a medium-dose of corticosteroids as a bolus medication in addition to their therapy. All hospitalized patients received hydroxychloroquine; 2 patients received ritonavir/lopinavir. Broad-spectrum antibiotics for prophylaxis were administered to all. One patient had an ischaemic stroke and died of sepsis. CONCLUSIONS: In the absence of any strong evidence regarding the treatment of heart transplant recipients infected with SARS-CoV-2, we faced a new challenge in managing viral infection in an immunosuppressed population. Because immunomodulation interaction with the infection seems to be crucial for developing severe forms of the disease, we managed to reduce immunosuppressive therapy by adding medium doses of corticosteroids. Despite the limited number of affected patients, this report suggests that special considerations should be given to treating coronavirus disease in the heart transplant recipient population.

The Psychosocial Assessment of Transplant Candidates: Inter-Rater Reliability and Predictive Value of the Italian Stanford Integrated Psychosocial Assessment for Transplantation (SIPAT).

BACKGROUND: The Stanford Integrated Psychosocial Assessment for Transplantation (SIPAT) is a comprehensive instrument developed to accurately assess the main pretransplant psychosocial risk factors that may impact transplant outcomes. OBJECTIVE: As neither established assessment procedures nor standardized tools designed to perform pretransplant psychosocial evaluation are currently available in Italy, the present study was designed to develop and preliminarily validate the Italian version of the SIPAT. METHODS: First, our team developed the Italian version of the SIPAT, following standard forward-back translation procedures. Then, the Italian version of the SIPAT was retrospectively and blindly applied to 118 randomly selected transplant cases (40 heart, 40 lung, and 38 liver) by 2 independent examiners. Information about the patients' final transplant listing recommendation (i.e., listing vs. deferral) was independently collected from the respective transplant teams. RESULTS: The inter-rater reliability of the Italian version of the SIPAT scores was substantial (Cohen's kappa = 0.77; P < 0.001). Moreover, the predictive value of the SIPAT ratings on the final transplant listing recommendation (i.e., listing vs. deferral) for each examiner was significant (both P < 0.05). CONCLUSION: Current findings suggest that SIPAT is a promising and reliable instrument in its Italian version. Given these excellent psychometric characteristics, the use of the SIPAT as part of the pretransplant psychosocial evaluation in Italian medical settings is highly encouraged.

A comparison of quality of life and psychological distress in heart transplantation patients at adult and pediatric ages.

BACKGROUND: The aim of the current study was to evaluate and compare the quality of life (QOL) and psychological status of adult patients who underwent heart transplant (HTx) at pediatric or adult ages. METHODS: The population consisted of two groups: patients who received HTx after 18 years old and pediatrics who received HTx between the age of 1 and 18 years. At the time of the study, all patients were over 18 years old. QOL data were collected from patients using 36-item Short-Form Health Survey (SF-36) and psychological distress by the Symptom checklist 90-revised questionnaire (SCL-90-R). RESULTS: A total of 232 HTx patients were evaluated; 217 were transplanted at an adult age and 15 at a pediatric one. QOL improved significantly in pediatrics patients in the general health perceptions subscale and physical pain subscale than adult patients. The Global Index of the psychological distress did not differ in the two groups, but the pediatric patients registered statistically significant higher scores on the interpersonal sensitivity symptom subscale (adult group 36 ± 0.42 vs pediatric group 81 ± 0.79), the hostility subscale (adult group m 39 ± 0.44 vs pediatric group 73 ± 0.76) and the paranoid ideation subscale (adult group 46 ± 0.46 vs pediatric group 96 ± 1.02). CONCLUSION: The pediatric heart recipients showed better quality of life, but they show marked sensitivity, hostility and paranoid ideation which increases the risk of mental distress and therefore their adherence to medical treatment.

MicroRNA signatures in cardiac biopsies and detection of allograft rejection.

BACKGROUND: Identification of heart transplant (HTx) rejection currently relies on immunohistology and immunohistochemistry. We aimed to identify specific sets of microRNAs (miRNAs) to characterize acute cellular rejection (ACR), antibody-mediated rejection (pAMR), and mixed rejection (MR) in monitoring formalin-fixed paraffin-embedded (FFPE) endomyocardial biopsies (EMBs) in HTx patients. METHODS: In this study we selected 33 adult HTx patients. For each, we chose the first positive EMB for study of each type of rejection. The next-generation sequencing (NGS) IonProton technique and reverse transcript quantitative polymerase chain reaction (RT-qPCR) analysis were performed on FFPE EMBs. Using logistic regression analysis we created unique miRNA signatures as predictive models of each rejection. In situ PCR was carried out on the same EMBs. RESULTS: We obtained >2,257 mature miRNAs from all the EMBs. The 3 types of rejection showed a different miRNA profile for each group. The logistic regression model formed by miRNAs 208a, 126-5p, and 135a-5p identified MR; that formed by miRNAs 27b-3p, 29b-3p, and 199a-3p identified ACR; and that formed by miRNAs 208a, 29b-3p, 135a-5p, and 144-3p identified pAMR. The expression of miRNAs on tissue, through in situ PCR, showed different expressions of the same miRNA in different rejections. miRNA 126-5p was expressed in endothelial cells in ACR but in cardiomyocytes in pAMR. In ACR, miRNA 29b-3p was significantly overexpressed and detected in fibroblasts, whereas in pAMR it was underexpressed and detected only in cardiomyocytes. CONCLUSIONS: miRNA profiling on FFPE EMBs differentiates the 3 types of rejection. Localization of expression of miRNAs on tissue showed different expression of the same miRNA for different cells, suggesting different roles of the same miRNA in different rejections.

Interventricular conduction disorders after orthotopic heart transplantation: risk factors and clinical relevance.

BACKGROUND: Causes and significance of interventricular conduction disorders (IVCDs) after orthotopic heart transplantation (OHT) are still unknown. METHODS: We retrospectively researched the presence of IVCDs in 240 patients who underwent bicaval OHT in three time periods: at day 1, after 1 year, and after 3 years from OHT. To evaluate the impact of the surgical technique, a control population treated with biatrial anastomosis was used. RESULTS: The most common IVCD was right bundle branch block (RBBB). Its presence at day 1 correlated with transpulmonary gradient before OHT. Its presence after 1 year and its development correlated with a 1-month acute rejection score≥2 (p = .050 and p = .006). The incidence of RBBB was higher in the biatrial control population (40.7% vs 23.8%, p < .001). CONCLUSIONS: RBBB is the most common IVCD. Its presence can be explained by a susceptibility of the right branch to heart positioning, pressure overload, and acute rejection. IVCDs do not affect prognosis.