Worldwide and Country-Specific Impact of the COVID-19 Pandemic on Heart Transplantation Volumes: A Longitudinal Analysis of 2020 and 2021.

BACKGROUND: COVID-19 pandemic hampered operational efficiency of heart transplant (HT) programs worldwide. Little is known about the global and country-specific changes in HT volumes during the pandemic years 2020-2021. We aimed to describe the global and country-level impact of the COVID-19 pandemic on HT volumes in 2020-2021. METHODS: This is a cross-sectional study of the Global Observatory on Donation and Transplantation, including the years 2019 to 2021. Among 60 countries that reported HT data in the years 2019-2020, we analyzed 52 countries with ≥1 transplant during each year. RESULTS: Overall, the number of HTs decreased during 2020 by 9.3% (1.82 to 1.65 PMP). While 75% (n=39/52) of countries experienced a decrease in HT volumes in 2020, volumes were maintained/increased in the remaining countries. Countries with maintained HT volumes had a higher organ donation rate in 2020 compared to those with decreased volumes (P=.03), the only significant predictor of change in HT volumes (P=.005). In 2021, a 6.6% recovery from the previous year's drop in global HT rate was noticed, reaching 1.76 HT PMP. Only one in five countries with reduced volumes in 2020 recovered their baseline volumes in 2021. Only 30.8% of countries with maintained volumes in 2020 had continued growth in HT volumes in 2021. CONCLUSION: Further work should define underlying causes of this heterogeneity in HT volume during the pandemic. Identifying policies and practices that helped certain countries mitigate the effect of the pandemic on HT activities may help other countries during similar health crises in the future.

Analysis of clinical cases of new coronavirus infection in patients with a history of heart transplantation

There is a description of two clinical cases of a new coronavirus infection COVID-19 in patients with a history of heart transplantation. Patients who receive immunosuppressants for life are at risk of developing infectious diseases. This requires the vigilance of doctors, especially in the face of a pandemic of a new coronavirus infection. Adequate and timely started therapy increases the effectiveness of treatment and reduces the risk of complications. The complex participation of different specialists is necessary to determine the tactics of treatment, correct pathogenetic and suppressive therapy.Copyright © 2021 Sovero Press Publishing House. All rights reserved.

Early Outcomes of Adult Heart Transplantation From COVID-19 Infected Donors.

BACKGROUND: There is a paucity of data on heart transplantation (HT) using COVID-19 donors. OBJECTIVES: This study investigated COVID-19 donor use, donor and recipient characteristics, and early post-HT outcomes. METHODS: Between May 2020 and June 2022, study investigators identified 27,862 donors in the United Network for Organ Sharing, with 60,699 COVID-19 nucleic acid amplification testing (NAT) performed before procurement and with available organ disposition. Donors were considered "COVID-19 donors" if they were NAT positive at any time during terminal hospitalization. These donors were subclassified as "active COVID-19" (aCOV) donors if they were NAT positive within 2 days of organ procurement, or "recently resolved COVID-19" (rrCOV) donors if they were NAT positive initially but became NAT negative before procurement. Donors with NAT-positive status >2 days before procurement were considered aCOV unless there was evidence of a subsequent NAT-negative result ≥48 hours after the last NAT-positive result. HT outcomes were compared. RESULTS: During the study period, 1,445 "COVID-19 donors" (COVID-19 NAT positive) were identified; 1,017 of these were aCOV, and 428 were rrCOV. Overall, 309 HTs used COVID-19 donors, and 239 adult HTs from COVID-19 donors (150 aCOV, 89 rrCOV) met study criteria. Compared with non-COV, COVID-19 donors used for adult HT were younger and mostly male (∼80%). Compared with HTs from non-COV donors, recipients of HTs from aCOV donors had increased mortality at 6 months (Cox HR: 1.74; 95% CI: 1.02-2.96; P = 0.043) and 1 year (Cox HR: 1.98; 95% CI: 1.22-3.22; P = 0.006). Recipients of HTs from rrCOV and non-COV donors had similar 6-month and 1-year mortality. Results were similar in propensity-matched cohorts. CONCLUSIONS: In this early analysis, although HTs from aCOV donors had increased mortality at 6 months and 1 year, HTs from rrCOV donors had survival similar to that seen in recipients of HTs from non-COV donors. Continued evaluation and a more nuanced approach to this donor pool are needed.

The Year in Cardiothoracic Transplant Anesthesia: Selected Highlights From 2021 Part II: Cardiac Transplantation.

This article spotlights the research highlights of this year that specifically pertain to the specialty of anesthesia for heart transplantation. This includes the research on recent developments in the selection and optimization of donors and recipients, including the use of donation after cardiorespiratory death and extended criteria donors, the use of mechanical circulatory support and nonmechanical circulatory support as bridges to transplantation, the effect of COVID-19 on heart transplantation candidates and recipients, and new advances in the perioperative management of these patients, including the use of echocardiography and postoperative outcomes, focusing on renal and cerebral outcomes.

Influencia de la pandemia por Covid 19 en el trasplante de órganos

En el mes de Diciembre (2019) se diagnosticó la infección viral que tuvo una rápida expansión. En el mes de Junio (2020) solo en 188 países fueron diagnosticados 35 millones de pacientes. Desgraciadamente en nuestro país los resultados de la atención a los enfermos (diagnostico, aislamiento, atención), fue peor que en otros muchos (Alemania, Italia, Corea, Taiwán, Grecia, Portugal, Francia, Japón y otros). 778 pacientes trasplantados sufrieron la infección, de ellos, 249 en la Comunidad de Madrid. La donación de órganos se redujo rápidamente debido a que las áreas de hospitalización, UCI, quirófanos, actividad hospitalaria en general hubo de dedicarse al tratamiento de los enfermos infectados. Hubo de asumir la reducción de trasplantes de riñón, hígado, corazón, pulmón, en casi el 90% de las cifras correspondientes a los dos años anteriores (en el mes de abril 0%), en el periodo marzo-Julio 2020. No se permitió el trasplante con donante vivo,” Split” o "Cluster”. Solo en la Comunidad de Madrid se realizaron 37 trasplantes menos en 2020 que en 2019. Los motivos de este descenso fue la reducción de camas en UCI, de posibilidades de utilización de quirófanos, menor número de facultativos, enfermeras, personal sanitario en general (861.112 infectados, de los cuales 36.000 eran sanitarios, con una mortalidad global de 36.000). Nuevos protocolos, formas de tratamiento, vacunación, hicieron posible volver a la cifra de trasplantes realizados entre 2018-2019.Alternate : On 31 December 2019 COVID-19 Viral infection was diagnoses. On june 2020 only in 188 countries 33 millons of infected people were detected. Unfortunately in Spain the results of the treatment has been worse than in Germany, Italy, Corea, Taiwan., Grece, Portugal, France, Japan, and others. 778 transplanted patients were infected. 249 of them in Madrid area. Organ donation was reduced. National Organization of Organ Trasplantation diminished donation, and transplantation of kidney, liver, heart, lung close to 90% (in april, 0%) from march to july 2020. Living rolated or split, and cluster trasplantation was not permited. In Madrid area, on 2020 were done 37 transplantation less than in 2019 the causes of that were the reduction of UCI beds, time in the OR, reduction of doctors and nurses. 861.112 infected people, 32.992 died and from the total number of patients, 36.000 were included as, doctors, nurses and other related with health care areas new protocols, hospitals, intensive care areas, etc were established along 2020 going back to the previous results obtained during 2018-2019.

Improving cardiovascular outcomes for patients with heart failure in sub-Saharan Africa: conference proceedings of the 2022 Nigerian Cardiovascular Symposium.

The Nigerian Cardiovascular Symposium is an annual conference held in partnership with cardiologists in Nigeria and the diaspora to provide updates in cardiovascular medicine and cardiothoracic surgery with the aim of optimising cardiovascular care for the Nigerian population. This virtual conference (due to the COVID-19 pandemic) has created an opportunity for effective capacity building of the Nigerian cardiology workforce. The objective of the conference was for experts to provide updates on current trends, clinical trials and innovations in heart failure, selected cardiomyopathies such as hypertrophic cardiomyopathy and cardiac amyloidosis, pulmonary hypertension, cardiogenic shock, left ventricular assist devices and heart transplantation. Furthermore, the conference aimed to equip the Nigerian cardiovascular workforce with skills and knowledge to optimise the delivery of effective cardiovascular care, with the hope of curbing 'medical tourism' and the current 'brain drain' in Nigeria. Challenges to optimal cardiovascular care in Nigeria include workforce shortage, limited capacity of intensive care units, and availability of medications. This partnership represents a key first step in addressing these challenges. Future action items include enhanced collaboration between cardiologists in Nigeria and the diaspora, advancing participation and enrollment of African patients in global heart failure clinical trials, and the urgent need to develop heart failure clinical practice guidelines for Nigerian patients.

Multivessel Epicardial Coronary Artery Thrombosis after Heart Transplantation

Introduction: Although cardiac allograft vasculopathy (CAV) remains one of the leading causes of graft failure after heart transplantation (HTx), simultaneous thrombosis of multiple epicardial coronary arteries (CA) is an uncommon finding. Case Report: A 43-year-old male patient with non-ischemic dilated cardiomyopathy underwent successful HTx in 2019. The first two years after HTx were uneventful, surveillance endomyocardial biopsies (EMB) did not reveal any rejection episodes, coronary CTA revealed only minimal non-calcified CA plaques. The patient was admitted to hospital due to fever and chest pain in 2021. Immunosuppressive therapy consisted of tacrolimus, mycophenolate-mofetil and methylprednisolone. ECG verified sinus rhythm. Laboratory test revealed elevated hsTroponin T, NT-proBNP and CRP levels. Cytomegalovirus, SARS-CoV-2-virus and hemoculture testing was negative. Several high-titre donor-specific HLA class I and II antibodies (DSAs;including complement-binding DQ7) could have been detected since 2020. Echocardiography confirmed mildly decreased left ventricular systolic function and apical hypokinesis. EMB verified mild cellular and antibody-mediated rejection (ABMR) according to ISHLT grading criteria. Cardiac MRI revealed inferobasal and apical myocardial infarction (MI);thus, an urgent coronary angiography was performed. This confirmed thrombotic occlusions in all three main epicardial CAs and in first diagonal CA. As revascularization was not feasible, antithrombotic therapy with acetylsalicylic acid, clopidogrel and enoxaparin was started for secondary prevention. Tests for immune system disorders, thrombophilia and cancer were negative. Patient suddenly died ten days after admission. Necropsy revealed intimal proliferation in all three main epicardial CAs, endothelitis, thrombosis, chronic pericoronary fat inflammation, fat necrosis, and subacute MI. CA vasculitis owing to persistent high-titre DSAs, chronic ABMR and acute cellular and antibody-mediated rejection led to multivessel CA thrombosis and acute multiple MI. ABMR after HTx may be underdiagnosed with traditional pathological methods. Pathologies affecting coronary vasculature of HTx patients with DSAs, unique manifestations of CAV lesions and occlusive thrombosis of non-stenotic, non-atherosclerotic lesions should be emphasized.Copyright © 2023

The Effect Of Covid-19 Infection On Sirolimus Metabolism In Heart Transplant

Introduction: Limited knowledge exists regarding the effect of Covid-19 on heart transplant recipients. Monitoring immunosuppressant levels is an important management strategy concerning the risk of graft rejection. Furthermore, how Covid-19 and its treatment affect sirolimus metabolism in solid organ transplants is not well understood. Here, we present a case of a heart transplant recipient with elevated sirolimus levels following Covid-19 infection. The elevated sirolimus levels occurred after previously being therapeutic on a steady dose and persisted despite significant dose reductions and no other known drug-drug interactions. Case Presentation: The patient is a 58-year-old male with a history of ischemic cardiomyopathy;status post orthotopic heart transplantation on 8/17/2009. The postoperative course was complicated by atrial tachycardia without rejection status post-ablation in 8/2020 and end-stage renal disease on hemodialysis. In January of 2022, the patient was instructed to present to the ER after missing dialysis due to Covid-like symptoms including generalized weakness, nausea, and shortness of breath. Covid-19 PCR returned positive. Before infection, the patient had been maintained on a steady dose of sirolimus 0.5 mg daily for 5 months with associated trough levels between the goal range of 4-8 ng/mL. At the time of infection, the patient's sirolimus was held due to elevated trough levels, and he was subsequently maintained on a dose of 0.5 mg every other day for the next few days. Seeing no improvement, the dose was then decreased to 0.25 mg every other day for the remainder of his admission. He expired on 2/09/2022 from Covid-19. Figure 1 shows the sirolimus trough:dose ratio before and after diagnosis of Covid-19. Discussion(s): To our knowledge, this is the first case presented of a heart transplant recipient with altered sirolimus metabolism status post Covid-19 infection without apparent drug-drug interactions. This may suggest a relationship between SARS-COV-2 viremia with sirolimus metabolism.Copyright © 2022

Impact of COVID-19 on 2020 transplant activity and waiting lists in France

The COVID-19 pandemic strongly affected organ procurement and transplantation in France, despite the intense efforts of all participants in this domain. In 2020, the identification and procurement of deceased donors fell by 12% and 21% respectively, compared with the mean of the preceding 2 years. Similarly, the number of new registrations on the national waiting list declined by 12% and the number of transplants by 24%. The 3-month cumulative incidence of death or drop out for worsening condition of patients awaiting a liver transplant was significantly greater in 2020 compared to the previous 2 years. Continuous monitoring at the national level of early post-transplant outcomes showed no deterioration for any organ in 2020. At the end of 2020, less than 1% of transplant candidates and less than 1% of graft recipients - of any organ - had died of COVID-19.Copyright © 2021 The Author(s)

Transplantation of hearts from SARS-CoV-2 positive donors.

Incidence of SARS-CoV-2 remains high in the population. Consequently, an increasing percentage of reported organ donors are also SARS-CoV-2 positive. Although donors may not have experienced COVID-19-related symptoms, there is a chance of unnoticed cardiovascular effects associated with this disease. Therefore, SARS-CoV-2 donor grafts have been regularly rejected for heart transplantation (HTx) for a long time. We hereby present three consecutive patients receiving grafts from SARS-CoV-2 positive donors (defined by the PCR cycle threshold value < 30). All patients underwent HTx after a previous triple mRNA vaccination (mRNA-BNT162b2 vaccine, Comirnaty) without adverse events and with a regular post-operative course. Cardiovascular magnetic resonance and endomyocardial biopsies confirmed excellent graft function without signs of rejection or viral myocarditis. After a mean follow-up of 135 days after HTx, all patients were in good conditions without heart failure, viral myocarditis, or SARS-CoV-2 infection. Thus, we conclude that HTx with SARS-CoV-2 positive donors seems safe and feasible.

Fifth bivalent omicron BA.4/BA.5 vaccination neutralization of SARS-CoV-2 in heart transplant recipients.

In 2022, the antigenically divergent SARS-CoV-2 omicron variants (BA.1, BA.2, BA.4, BA.5) outcompeted previous variants and continued to cause substantial numbers of illnesses and deaths. We evaluated the safety and immunogenicity of the bivalent original/omicron BA.4/BA.5 Pfizer/BioNTech vaccine administered as a fifth dose to heart transplant recipients (HTxRs). We compared neutralization (using live virus assays) of SARS-CoV-2-infected cells in serum samples from HTxRs who had previously received 4 doses of the monovalent BNT162b2 vaccine with samples from HTxRs with breakthrough infection after 4 monovalent BNT162b2 doses. The fifth vaccination induced high neutralization efficiency against the wild-type virus and omicron BA.1, BA.2, BA.4, and BA.5 variants, with significantly higher neutralization efficiency being induced in HTxRs with breakthrough infection than in those without. Neutralizing titers in those with breakthrough infection were sustained above the level induced by the fifth dose in the uninfected. We conclude that the fifth bivalent vaccine is immunogenic, including to variants, with higher vaccine immunogenicity conferred by breakthrough infection. Nevertheless, the clinical protection conferred by the fifth dose is yet to be determined. The sustained neutralization responses in those with breakthrough infection support the notion of delaying booster in those with natural breakthrough infection.

Treatment and Outcome of COVID-19 after Heart Transplantation: Update from a German Transplant Center

Background: The SARS-CoV-2 pandemic is leading to hospitalizations and increased mortality worldwide. With potentially high prevalence and severity of COVID-19 in cardiac transplantation, there is a great need to generate data in this at-risk cohort. We report here our experience on outcome and treatment of heart transplant recipients infected with SARS-CoV-2 at a German transplant center longitudinally over the previous pandemic waves. Method(s): All adult patients who had received a heart transplant at our center and had confirmed COVID-19 infection between December 2020 and July 2022 (n = 48) were included and retrospectively characterized. Result(s): The median age was 60.5 (46.3-63.8) years, and the majority were male (83%). The hospitalization rate was 83%. Comorbidities included diabetes (31%), arterial hypertension (73%), and chronic renal failure (90%). The percentage of SARS-CoV-2 positive patients since the beginning of our vaccination campaign (03/2021) was 90%, while from those 43 patients, 88% were fully vaccinated at the time of infection (vaccine breakthrough). The median time from vaccination to infection within those patients was 138 (85-225) days. Antiviral therapy was given in 83% of all cases, and passive immunization (convalescent plasma/monoclonal antibodies) was performed in 98% of all cases. Oxygen administration was required in 10% of patients;only one patient required noninvasive ventilation (2%), and no patient required invasive ventilation or mechanical cardiovascular support (ECMO). No new cardiovascular or thromboembolic events were found, and we observed no COVID-19-associated mortality. Conclusion(s): Under increasing numbers of vaccinated patients and treatment options, we could not detect severe courses or increased mortality of COVID-19 in heart transplanted patients. Prospective studies are needed to make better prognostic estimates of COVID-19 in (heart) transplanted patients in the future.

Fulminant Myocarditis (Fm) Requiring Heart Transplantation: A Rare Sequela of Sars-Cov-2 Infection

Background SARS-CoV-2 infection, the cause of COVID-19, has been associated with myocarditis. Fulminant myocarditis (FM) is rare. Case A 30-year-old male with a past medical history of SARS-CoV-2 infection 7 months prior, presented with a 2-week history of malaise, cough, dyspnea, and signs of cardiogenic shock. He was fully vaccinated 9 months prior. Respiratory viral PCR testing, including SARSCoV-2, was negative. HS-troponin was >20,000 ng/L (NR: 0-53 ng/L). An echocardiogram revealed a dilated cardiomyopathy with an EF of 15-20%. Cardiac catheterization revealed no CAD. Workup for an autoimmune etiology was unrevealing. His condition worsened and he required inotropic support, eventual placement of an LVAD, and initiation of ECMO. He was not able to tolerate cardiac MRI or endomyocardial biopsy. Ultimately, he underwent orthotopic heart transplantation. Pathologic examination of the explanted heart confirmed lymphocytic myocarditis. Decision-making Myocardial injury due to the cardiotropic nature of SARS CoV-2 has been increasingly reported. There has been a 42% increase in viral myocarditis, and the risk is 16 times greater with a history of COVID-19. Symptomatic myocarditis typically manifests within weeks of infection. Such a delayed presentation has not been described. Data from autopsies of deceased COVID-19 patients revealed a 25% to 50% detection rate of SARS-CoV-2 mRNA in the myocardium. One case report described a deceased FM patient with multiple negative SARS-CoV-2 PCR tests, including bronchial lavage samples, having confirmed SARS-CoV-2 within the myocardium postmortem. Hence SARS-Cov-2 can persist in the heart after the resolution of respiratory infection, possibly leading to ongoing inflammation and myocardial damage. This may explain why our patient presented 7 months after a resolved infection. Conclusion SARS-CoV-2 is cardiotropic and can cause fulminant myocarditis even in the absence of a detectable respiratory infection. Hence closer monitoring of post-COVID-19 patients, including screening for subclinical myocarditis, may be prudent. Further research on monitoring and an evaluation of the clinical utility of medical therapy, is also warranted.Copyright © 2023 American College of Cardiology Foundation

Utilization of COVID-19 positive donors for Heart transplantation and associated short-term outcomes.

BACKGROUND: The safety and efficacy of using COVID-19 positive donors in heart transplantation (HT) are increasingly relevant, but not well established. The present study evaluated the characteristics and utilization of such donors and associated post-HT outcomes. METHODS: All adult (≥18 years old) potential donors and HT recipients in the United States from April 21, 2020 to March 31, 2022 were included. Donor COVID-19 status was defined by the presence (or absence) of any positive test within 21 days of organ recovery. Donor and recipient characteristics and post-HT outcomes, including a primary composite of death, graft failure, and re-transplantation, were compared by donor COVID-19 status. RESULTS: Of 967 COVID-19(+) potential donors, 19.3% (n = 187) were used for HT compared to 26.7% (n = 6277) of COVID-19(-) donors (p < 0.001). Transplanted COVID-19(+) vs COVID-19(-) donors were younger, but otherwise were similar. Recipients of hearts from COVID-19+ vs COVID-19(-) donors less frequently received pre-HT inotropes (24.1% vs 31.7%, p = 0.023) and ventricular assist device therapy (29.7% vs 36.8%, p = 0.040). There were no significant differences in any post-HT outcome by donor COVID-19 status, including the primary composite outcome at 90 days (5.4% vs 5.6%, p = 0.91). Among COVID-19(+) donors, the presence of a subsequent negative test prior to transplant was not associated with posttransplant outcomes. CONCLUSIONS: Our results suggest that carefully selected COVID-19 positive donors may be used for HT with no difference in short-term post-transplant outcomes. Additional data regarding donor and recipient treatments and impact of vaccination should be collected to better inform our use of organs from COVID(+) donors.

COVID-19 in heart transplant recipients.

Introduction: After solid organ transplantation, patients require lifelong immunosuppressive medication, increasing susceptibility to COVID-19. We evaluated the clinical outcomes of heart transplant recipients in patients with COVID-19. Methods: We enrolled twenty-two COVID-19 cases of adult heart transplantation from February 2020 to September 2021. Results: The most common symptoms in patients were fever and myalgia. The death occurred in 3 (13.6 %). Conclusion: Although heart transplantation mortality may increase in the acute rejection phase concomitant with COVID-19, immunosuppressive dose reduction may not be necessary for all heart transplant patients with COVID-19.

SARS-CoV-2 Vaccination-Induced Immunogenicity in Heart Transplant Recipients.

Among heart transplant (HT) recipients, a reduced immunological response to SARS-CoV-2 vaccination has been reported. We aimed to assess the humoral and T-cell response to SARS-CoV-2 vaccination in HT recipients to understand determinants of immunogenicity. HT recipients were prospectively enrolled from January 2021 until March 2022. Anti-SARS-CoV-2-Spike IgG levels were quantified after two and three doses of a SARS-CoV-2 vaccine (BNT162b2, mRNA1273, or AZD1222). Spike-specific T-cell responses were assessed using flow cytometry. Ninety-one patients were included in the study (69% male, median age 55 years, median time from HT to first vaccination 6.1 years). Seroconversion rates were 34% after two and 63% after three doses. Older patient age (p = 0.003) and shorter time since HT (p = 0.001) were associated with lower antibody concentrations after three vaccinations. There were no associations between vaccine types or immunosuppressive regimens and humoral response, except for prednisolone, which was predictive of a reduced response after two (p = 0.001), but not after three doses (p = 0.434). A T-cell response was observed in 50% after two and in 74% after three doses. Despite three vaccine doses, a large proportion of HT recipients exhibits a reduced immune response. Additional strategies are desirable to improve vaccine immunogenicity in this vulnerable group of patients.

Effect of a Fourth Dose of mRNA Vaccine and of Immunosuppression in Preventing SARS-CoV-2 Breakthrough Infections in Heart Transplant Patients.

Patients with heart transplantation (HT) have an increased risk of COVID-19 disease and the efficacy of vaccines on antibody induction is lower, even after three or four doses. The aim of our study was to assess the efficacy of four doses on infections and their interplay with immunosuppression. We included in this retrospective study all adult HT patients (12/21-11/22) without prior infection receiving a third or fourth dose of mRNA vaccine. The endpoints were infections and the combined incidence of ICU hospitalizations/death after the last dose (6-month survival rate). Among 268 patients, 62 had an infection, and 27.3% received four doses. Following multivariate analysis, three vs. four doses, mycophenolate (MMF) therapy, and HT < 5 years were associated with an increased risk of infection. MMF ≥ 2000 mg/day independently predicted infection, together with the other variables, and was associated with ICU hospitalization/death. Patients on MMF had lower levels of anti-RBD antibodies, and a positive antibody response after the third dose was associated with a lower probability of infection. In HT patients, a fourth dose of vaccine against SARS-CoV-2 reduces the risk of infection at six months. Mycophenolate, particularly at high doses, reduces the clinical effectiveness of the fourth dose and the antibody response to the vaccine.

Improved immunogenicity following the third dose of BNT162b2 mRNA vaccine in heart transplant recipients.

OBJECTIVES: The immunogenicity of two-dose severe acute respiratory syndrome coronavirus 2 vaccine is lower among heart transplant (HTx) recipients, compared with the general population. Our aim was to assess the immunogenicity of a third-dose vaccine in HTx recipients. METHODS: This is a prospective cohort study of HTx recipients who received a third dose of the BNT162b2 vaccine. Immunogenicity was assessed by serum levels of anti-spike immunoglobulin G (S-IgG), taken at baseline and 14-28 days after the third dose. Titres above 50 U/ml were interpreted positive. RESULTS: We Included 42 HTx recipients at a median age of 65 years [interquartile range (IQR) 58-70]. At baseline, the median of 27 days (IQR 13-42) before the third dose and the median titre of the whole group was 18 U/ml (IQR 4-130). Only 14 patients (33%) were S-IgG seropositive. After the third dose, the proportion of seropositive patients increased significantly to 57% (P = 0.05) and the median titre increased significantly to 633 U/ml (IQR 7-6104, P < 0.0001). Younger age at HTx (OR per 1-year decrease 1.07, P = 0.05), low tacrolimus serum level (OR per 1-unit decrease 2.28, P = 0.02), mammalian target of rapamycin use (OR 13.3, P = 0.003), lack of oral steroids use (OR 4.17, P = 0.04) and lack of calcineurin inhibitor use (71% of responders vs 100% non-responders received calcineurin inhibitors, P = 0.01) were predictors of seropositive result after the third dose. However, no significant association was detected following adjustment for baseline S-IgG titre. CONCLUSIONS: Third-dose booster of BNT162b2 vaccine significantly increased immunogenicity among HTx recipients who previously received a two-dose vaccine.