A heart transplant center experience with basiliximab induction strategies: A double edged sword?

BACKGROUND: The use of induction immunosuppression for heart transplantation (HT) is debated given the uncertain benefit and potential risks of infection and malignancy. METHODS: This is a retrospective single-center analysis of 475 consecutive HT recipients from 2003 to 2020 grouped by use of induction with basiliximab group (BG) and the no basiliximab group (NBG). Subgroup analysis by era compared pre-2016 standard-basiliximab (BX) induction and 2016-2020 with selective-BX use as part of a calcineurin-inhibitor-sparing regimen. RESULTS: When adjusted for confounders (sex, age, PRA, eGFR), the BG was less likely to have acute cellular rejection (ACR) (OR.42, p < .001), but had more antibody mediated rejection (AMR) (OR 11.7, p < .001) and more cardiac allograft vasculopathy (CAV) (OR 3.8, p = .04). There was no difference between BG and NBG in the incidence of malignancies or infections. When stratified by era (pre-2016 vs. 2016-2020), ACR remained less common in the BG than the NBG (36% vs. 50%, p = .045) groups, while AMR remained more common (9.7 vs. 0% p = .005). There was no significant difference in conditional survival comparing pre-and post-2016 NBG (HR 2.20 (95% CI.75-6.43); however, both pre-2016 BG and post-2016 BG have significantly higher mortality (HR 2.37 [95% CI 1.02-5.50) and HR 2.69 (95% CI 1.08-6.71), p = .045 and.03, respectively]. CONCLUSION: Basiliximab reduces the incidence of ACR but increases the risk of AMR, CAV, and may be associated with increased mortality. Mechanistic studies are needed to describe a potential T-cell-escape mechanism with enhanced humoral immunity.

Donor-derived cell-free DNA is associated with cardiac allograft vasculopathy.

BACKGROUND: The role of donor-derived cell-free DNA (dd-cfDNA) in screening for cardiac allograft vasculopathy (CAV) is unknown. We hypothesized that dd-cfDNA correlates with CAV, markers of inflammation, and angiogenesis in stable heart transplant (HT) recipients. METHODS: Sixty-five HT recipients ≥2 years post-transplant, without recent rejection, were stratified by high (≥0.12%) versus low levels (<0.12%) of dd-cfDNA. A targeted amplification, next-generation sequencing assay (AlloSure® ; CareDx, Inc.) was used to detect dd-cfDNA. Peripheral blood inflammatory and angiogenesis markers were assessed using a multiplex immunoassay system (Bioplex® ). RESULTS: Of 65 patients, 58 patients had a known CAV status and were included. Thirty had high levels of dd-cfDNA (≥0.12%), and 28 had low levels (<0.12%). CAV was present in 63% of patients with high dd-cfDNA vs. 35% with low dd-cfDNA (p = .047). Donor-specific antibodies were present in 25% of patients with high dd-cfDNA vs. 3.8% in those with low dd-cfDNA (p = .03). There were no differences in rejection episodes, inflammatory, or angiogenesis markers. Importantly, dd-cfDNA levels were not different when stratified by time post-transplant. CONCLUSIONS: Higher dd-cfDNA levels were associated with CAV in stable chronic HT recipients. Further studies are warranted to investigate a possible association between dd-cfDNA levels and CAV severity and whether dd-cfDNA can predict CAV progression.

Early experience of COVID-19 in 2 heart transplant recipients: Case reports and review of treatment options.

The coronavirus disease 2019 (COVID-19) pandemic poses special challenges to immunocompromised transplant patients. Given the paucity of proven data in treating COVID-19, management of these patients is difficult, rapidly evolving, and mainly based on anecdotal experience. We report 2 cases of heart transplant (HT) recipients with COVID-19. The first is a 59-year-old female with HT in 2012 who presented on March 20, 2020 with fever, hypoxia, and ground-glass opacities on chest X-ray. She quickly progressed to acute hypoxic respiratory failure and vasoplegic shock. Despite reduction in immunosuppression and treatment with tocilizumab, intravenous immunoglobulin, hydroxychloroquine, lopinavir/ritonavir, and broad-spectrum antibiotics, she ultimately died from multiorgan failure. The second case is a 75-year-old man with HT in 2000 who presented on April 2, 2020 after curbside testing revealed positive COVID-19. Given a milder presentation compared to the first patient, antimetabolite was discontinued and only hydroxychloroquine was started. Because of a lack of clinical improvement several days later, tocilizumab, methylprednisolone, and therapeutic anticoagulation were initiated. The patient clinically improved with decreasing oxygen requirements and was discharged home. These 2 cases highlight the wide range of different presentations of COVID-19 in HT recipients and the rapidity with which the management of these patients is evolving.

Deep Y-Descent in Right Atrial Waveforms Following Left Ventricular Assist Device Implantation.

BACKGROUND: Characterization of right heart catheterization (RHC) waveforms provides diagnostic and clinical information in heart failure patients. We aimed to investigate the implication of RHC waveforms, specifically the y-descent, in patients with left ventricular assist device (LVAD). METHODS AND RESULTS: Patients underwent RHC and waveforms were quantified prior to and 6 months after LVAD implantation. The impact of a deep y-descent (>3 mmHg) on echocardiographic measures of right heart function and 1-year hemocompatibility-related adverse event rates were investigated. Eighty-nine patients (median 59 years old, 65 male) underwent RHC. RHC waveform showed unique changes following LVAD implantation, particularly an increase in the steepness of the y-descent. A post-LVAD deep y-descent was associated with reduced right ventricular function and enlarged right heart. Patients with post-LVAD deep y-descent had higher rates of gastrointestinal bleeding (0.866 vs 0.191 events/year) and stroke (0.199 vs 0 events/year) compared with those without (P< .05 for both). CONCLUSION: RHC waveforms characterized by deep y-descent on RHC waveform during LVAD support was associated with impaired right ventricular function and worse clinical outcomes.

Discordance Between Clinical Assessment and Invasive Hemodynamics in Patients With Advanced Heart Failure.

BACKGROUND: Historically, invasive hemodynamic guidance was not superior compared to clinical assessment in patients admitted with acute decompensated heart failure (ADHF). This study assessed the accuracy of clinical assessment vs invasive hemodynamics in patients with ADHF. METHODS AND RESULTS: We conducted a prospective cohort study of patients admitted with ADHF. Prior to right-heart catheterization (RHC), physicians categorically predicted right atrial pressure, pulmonary capillary wedge pressure, cardiac index and hemodynamic profile (wet/dry, warm/cold) based on physical examination and clinical data evaluation (warm = cardiac index > 2.2 L/min/m2; wet = pulmonary capillary wedge pressure > 18 mmHg). We collected 218 surveys (of 83 cardiology fellows, 55 attending cardiologists, 45 residents, 35 interns) evaluating 97 patients. Of those patients, 46% were receiving inotropes prior to RHC. The positive and negative predictive values of clinical assessment compared to RHC for the cold and wet subgroups were 74.7% and 50.4%. The accuracy of categorical prediction was 43.6% for right atrial pressure, 34.4% for pulmonary capillary wedge pressure and 49.1% for cardiac index, and accuracy did not differ by clinician (P > 0.05 for all). Interprovider agreement was 44.4%. Therapeutic changes following RHC occurred in 71.1% overall (P < 0.001). CONCLUSIONS: Clinical assessment of patients with advanced heart failure presenting with ADHF has low accuracy across all training levels, with exaggerated rates of misrecognition of the most high-risk patients.

Hypogammaglobulinemia following heart transplantation: Prevalence, predictors, and clinical importance.

Hypogammaglobulinemia (HGG) can occur following solid organ transplantation. However, there are limited data describing the prevalence, risk factors, and clinical outcomes associated with HGG following heart transplantation. We retrospectively reviewed data of 132 patients who had undergone heart transplantation at our institution between April 2014 and December 2018. We classified patients into three groups based on the lowest serum IgG level post-transplant: normal (≥700 mg/dL), mild HGG (≥450 and <700 mg/dL), and severe HGG (<450 mg/dL). We compared clinical outcomes from the date of the lowest IgG level. Mean age was 57 (47, 64) years, and 94 (71%) patients were male. Prevalence of severe HGG was the highest (27%) at 3-6 months following heart transplantation and then decreased to 5% after 1 year. Multivariate analysis showed that older age and Caucasian race were independent risk factors for HGG. Overall survival was comparable between the groups; however, survival free of infection was 73%, 60%, and 45% at 1 year in the normal, mild HGG, and severe HGG groups, respectively (P = .013). In conclusion, there is a high prevalence of HGG in the early post-heart transplant period that decreases over time. HGG is associated with an increased incidence of infection.

Aortic Insufficiency and Hemocompatibility-related Adverse Events in Patients with Left Ventricular Assist Devices.

AIM: Hemocompatibility-related adverse events (HRAE) are a major cause of readmissions in patients with left ventricular assist devices (LVAD). The impact of aortic insufficiency (AI) on HRAE remains uncertain. We aimed to investigate the impact of AI on HRAE. METHODS AND RESULTS: Patients who underwent LVAD implantation between August 2014 and July 2017 and had echocardiograms 3 months post-LVAD implantation were enrolled. AI severity was assessed by measuring the systolic/diastolic ratio of flow and the rate of diastolic flow acceleration using Doppler echocardiography of the outflow cannula. Regurgitation fraction was derived from these parameters. Significant AI was defined as regurgitation fraction > 30%. Among 105 patients (median age, 56 years; 76% male), 36 patients (34%) had significant AI. Baseline characteristics were statistically not significantly different between those with and without significant AI except for higher rates of ischemic etiology and atrial fibrillation in the significant AI group (P < 0.05 for both). One-year survival free from HRAE was 44% in patients with AI compared to 67% in patients without significant AI (P = 0.018). The average hemocompatibility score, which defines the net burden of HRAE, was higher in the AI group (1.72 vs 0.64; P = 0.009), due mostly to higher tier I (mild HRAE; P = 0.034) and tier IIIB scores (severe HRAE; P = 0.011). CONCLUSION: Significant AI, as assessed by Doppler echocardiographic parameters, was associated with HRAE during LVAD support.

The forkhead transcription factor Foxo3 negatively regulates natural killer cell function and viral clearance in myocarditis.

Aims: Foxo3 is a transcription factor involved in cell metabolism, survival, and inflammatory disease. However, mechanistic insight in Foxo3 effects is still limited. Here, we investigated the role of Foxo3 on natural killer (NK) cell responses and its effects in viral myocarditis. Methods and results: Effects of Foxo3 on viral load and immune responses were investigated in a model of coxsackie virus B3 myocarditis in wild-type (WT) and Foxo3 deficient mice. Reduced immune cell infiltration, viral titres, and pro-inflammatory cytokines in cardiac tissue were observed in Foxo3-/- mice 7 days post-infection (p.i.). Viral titres were also attenuated in hearts of Foxo3-/- mice at Day 3 while interferon-γ (IFNγ) and NKp46 expression were up-regulated suggesting early viral control by enhanced NK cell activity. CD69 expression of NK cells, frequencies of CD11b+CD27+ effector NK cells and cytotoxicity of Foxo3-/- mice was enhanced compared to WT littermates. Moreover, microRNA-155 expression, essential in NK cell activation, was elevated in Foxo3-/- NK cells while its inhibition led to diminished IFNγ production. Healthy humans carrying the longevity-associated FOXO3 single nucleotide polymorphism (SNP) rs12212067 exhibited reduced IFNγ and cytotoxic degranulation of NK cells. Viral inflammatory cardiomyopathy (viral CMI) patients with this SNP showed a poorer outcome due to less efficient virus control. Conclusion: Our results implicate Foxo3 in regulating NK cell function and suggest Foxo3 playing an important role in the antiviral innate immunity. Thus, enhanced FOXO3 activity such as in the polymorphism rs12212067 may be protective in chronic inflammation such as cancer and cardiovascular disease but disadvantageous to control acute viral infection.

Consequences of Retained Defibrillator and Pacemaker Leads After Heart Transplantation-An Underrecognized Problem.

BACKGROUND: Cardiovascular implantable electronic devices (CIEDs) are common in patients undergoing heart transplantation (HT), and complete removal is not always possible at the time of transplantation. METHODS: We retrospectively assessed the frequency of retained CIED leads and clinical consequences in consecutive HT patients from 2013 to 2016. Clinical outcomes included bacteremia, upper-extremity deep venous thrombosis (UEDVT), lead migration, and inability to perform magnetic resonance imaging (MRI). RESULTS: A total of 138 patients (55 ± 11 years of age, 76% male) were identified; 37 (27%) had retained lead fragments (RLFs) at discharge. Patients with RLFs were older, had longer lead implantation time before HT, and a higher prevalence of dual-coil CIED leads compared with those without RLFs (P < .05 for all). Lead implantation time was identified as an independent predictor for RLFs (P < .05). Patients with RLFs had a higher frequency of DVT compared with the non-RLF group during the 1-year study period (42% vs 21%; P < .04). There was no difference in bacteremia. Fourteen patients (38%) could not undergo clinically indicated MRI. CONCLUSION: RLFs after HT occur commonly and are associated with a higher rate of UEDVT and limit the use of MRI. Although no significant difference was found in the rates of bacteremia between the groups, this finding might be explained by the overall low incidence. Patients with risk factors for RLFs should be identified before transplantation, and complete lead removal should be considered with a multidisciplinary approach.

The Effect of Left Ventricular Assist Device Therapy on Cardiac Biomarkers: Implications for the Identification of Myocardial Recovery.

PURPOSE OF REVIEW: Left ventricular assist device (LVAD) therapy serves as mainstay therapy for bridge to transplantation and destination therapy. Evidence is now mounting on the role of LVAD therapy as bridge to recovery. In the current review, we will summarize the data on biomarkers of myocardial recovery following LVAD implantation. RECENT FINDINGS: Myocardial recovery can occur spontaneously, following pharmacological intervention and in the setting of mechanical circulatory support such as LVAD. Several biomarkers such as B-type natriuretic peptide (BNP), N-terminal pro B-type natriuretic peptide (NT-proBNP), ST2, etc. have been identified and are being used to guide medical therapy in heart failure (HF) patients. However, recent data raised concern that those biomarkers may not be helpful in managing heart failure patients in general, and as such questioned their use in the advanced heart failure population. At this point, the use of biomarker to identify patients with myocardial recovery during LVAD support has not been established, and LVAD explantation remains a decision driven by echocardiographic and hemodynamics improvement. HF biomarkers in monitoring myocardial and neurohormonal activation response to mechanical unloading and medical therapy could be valuable. However, at this time, there is inadequate evidence to select a single or a set of HF biomarkers to reliably identify patients bridged to recovery for LVAD explantation.

Statin therapy improves survival in patients with severe pulmonary hypertension: a propensity score matching study.

Inflammation is an increasingly recognized hallmark of pulmonary hypertension (PH). Statins have been shown to attenuate key pathologic mechanisms via pleiotropic effects in animal models. However, clinical benefit of statins in patients with PH is unknown and their effect on mortality has not been studied. We performed a retrospective analysis of patients between January 2002 to January 2012, with severe PH (pulmonary artery systolic pressure ≥60 mmHg) and preserved left ventricular function (ejection fraction ≥50%), defined by transthoracic echocardiograms. Patients were divided into two groups based on statin therapy for 12 consecutive months after diagnosis of PH. Propensity score matching was performed. Subgroup analysis was done based on COPD status. Study endpoint was 1-year all-cause mortality and hospitalization. 2363 patients (age 71 ± 16; 31% male) were included; 140 (6%) were on statin therapy. Overall 1-year mortality was 34%. Following propensity score matching, 138 patients were included in the statin group and 624 patients in the no-statin group; all-cause mortality was significantly lower in the statin group compared with the no-statin group [15.2 vs. 33.8%, HR 0.42 (95% CI 0.27, 0.66), p < 0.001], but hospitalization was comparable between two groups. After stratifying patients based on COPD status, patients with COPD showed a marginally significant survival benefit from statins [HR 0.53 (95% CI 0.26, 1.10), p = 0.09]; and statins significantly reduced 1-year all-cause mortality in patients without COPD [HR 0.36 (95% CI 0.19, 0.67), p = 0.001]. We found no significant difference in the effect of statins on patients with COPD compared to those without (p = 0.16). Statin therapy is associated with reduced mortality risk in patients with severe PH and preserved left ventricular function. This beneficial effect was not found to be dependent on COPD status. These novel findings should be confirmed in large randomized trials.

Target temperature management of 33 degrees C exerts beneficial haemodynamic effects after out-of-hospital cardiac arrest.

BACKGROUND: Accumulating evidence indicates that target temperature management (TTM) is beneficial in patients resuscitated after cardiac arrest since it appears to improve neurological outcome. However, the optimal cooling method (surface vs. intravascular) has not yet been specified. Substantial heart disease is present in most of these patients and therefore haemodynamic effects of cooling need to be considered very carefully. We analysed the haemodynamic response to TTM in patients treated with surface versus intravascular cooling following out-of-hospital cardiac arrest. METHODS AND RESULTS: In this observational study 63 consecutive subjects presenting to the hospital after successful resuscitation following of out-of-hospital cardiac arrest received an intravascular (40 patients) or external cooling device (23 patients) to induce TTM. While with intravascular cooling the target temperature of 33 degrees C was reached after 159 minutes, the minimum temperature achieved with surface cooling was about 35 degrees C after 437 minutes. Haemodynamic parameters were recorded in a 4-hour rhythm for the first 12 hours after induction of hypothermia. Generally, TTM of 33 degrees C resulted in a higher systemic vascular resistance index (749 vs. 467 dyn*sec/cms/m2; P= 0.04) but also in a marked reduction of heart rate (67.70 vs. 100.00 bpm; P < 0.001), a higher mixed venous oxygen saturation (76 vs. 68%; P = 0.016), and a higher stroke volume index (45 vs. 33 mI/m2; P = 0.036). TTM additionally resulted in a higher cardiac power index (0.55 vs. 0.46 Watt/m2; P = 0.024). CONCLUSION: TTM of 33 degrees C compared to 35 degrees C exerts beneficial haemodynamic effects and might be viewed as an adjunct inotropic therapy avoiding the undesired side effects of vasoactive substances.

Endothelin receptor polymorphisms in the cardiovascular system: potential implications for therapy and screening.

Since its discovery in 1988, the endothelin system has been employed in multiple physiological and pathological roles. Endothelin-1 (ET-1) is not only a major regulator of vascular tone and cardiac contractility but also exerts mitogenic effects and is involved in inflammatory responses. ET-1 acts via two endothelin receptors located mainly on smooth muscle and endothelial cells through complex intracellular pathways differing between receptors and cell types. Polymorphisms of the endothelin receptor A have been associated not only with the risk in pulmonary arterial hypertension (PAH), systolic heart failure and systemic hypertension but are also of prognostic significance in dilated cardiomyopathy. Polymorphisms of endothelin receptors might lead to altered endothelin signaling and influence the response to endothelin receptor antagonist therapy in PAH in light of pharmacogenetics. This review will summarize the role of ET-1 within major cardiovascular pathologies and discuss endothelin receptor polymorphisms with special emphasis on potential therapeutic and screening implications.

Emergency Department Use and Hospital Mortality Among Heart Transplant Recipients in the United States.

BACKGROUND: Annual heart transplant (HT) volumes have increased, as have post-HT outpatient care needs. Data on HT-related emergency department (ED) visits are limited. METHODS AND RESULTS: A retrospective analysis of 177 450 HT patient ED visits from the 2009 to 2018 Nationwide Emergency Department Sample was conducted. HT recipients, primary diagnoses, and comorbidities associated with ED visits were identified via International Classification of Diseases, Ninth Revision (ICD-9) and International Classification of Diseases, Tenth Revision (ICD-10) codes. Multivariable logistic regression was used to predict outcomes of hospital admission and death. HT volumes and HT-related ED visits increased from 2009 to 2018. Infection was the most common primary diagnosis (24%), and cardiac primary diagnoses represented 10% of encounters. Hospital admissions occurred in 48% of visits, but overall mortality was low (1.6%). Length of stay was 3.1 days (interquartile range, 1.6-5.9 days), and comorbidity burden was high: 42% had hypertension, 38% had diabetes, and 31% had ≥2 comorbidities. Those aged ≥65 years had significantly higher odds of admission (odds ratio [OR], 2.14 [95% CI, 1.97-2.33]) and death (OR, 2.06 [95% CI, 1.61-2.62]). Comorbidities increased odds of admission (OR, 1.62 [95% CI, 1.51-1.75]) but not death. Renal primary diagnosis had the highest risk of admission (OR, 4.1 [95% CI, 3.6-4.6]), but cardiac primary diagnosis had the highest odds of death (OR, 11.6 [95% CI, 9.1-14.8]). CONCLUSIONS: HT-related ED visits increased from 2009 to 2018 with high admission rates but low in-hospital mortality, suggesting an opportunity to improve prehospital care. Older patients and those with cardiac primary diagnoses had the highest risk of death. The observed contrast between predictors of admission and mortality signals a need for further study to improve risk stratification and outpatient care strategies.

Understanding and Investigating Sex-Based Differences in Heart Transplantation: A Call to Action.

Women represent only about 25% of heart transplant recipients annually. Although the number of women living with advanced heart failure remains unknown, epidemiologic research suggests that more women should be receiving advanced heart failure therapies. Sex differences in risk factors, presentation, response to pharmacotherapy, and outcomes in heart failure have been well described. Yet, less is known about sex differences in heart transplant candidate selection, waitlist management, donor selection, perioperative considerations, and post-transplant management and outcomes. The purpose of this review was to summarize the existing published reports related to sex differences in heart transplantation, highlighting areas in which sex-based considerations are well described and supported by available evidence, and emphasizing topics that require further study.

The End of Endomyocardial Biopsy?: A Practical Guide for Noninvasive Heart Transplant Rejection Surveillance.

Noninvasive heart transplant rejection surveillance using gene expression profiling (GEP) to monitor immune activation is widely used among heart transplant programs. With the new development of donor-derived cell-free DNA (dd-cfDNA) assays, more programs are transitioning to a predominantly noninvasive rejection surveillance protocol with a reduced frequency of endomyocardial biopsies. As a result, many practical questions arise that potentially delay implementation of these valuable new tools. The purpose of this review is to provide practical guidance for clinicians transitioning toward a less invasive acute rejection monitoring protocol after heart transplantation, and to answer 10 common questions about the GEP and dd-cfDNA assays. Evidence supporting GEP and dd-cfDNA testing is reviewed, as well as guidance on test interpretation and future directions.

Comparison of Glidescope Core, C-MAC Miller and conventional Miller laryngoscope for difficult airway management by anesthetists with limited and extensive experience in a simulated Pierre Robin sequence: A randomized crossover manikin study.

BACKGROUND: Video laryngoscopy is an effective tool in the management of difficult pediatric airway. However, evidence to guide the choice of the most appropriate video laryngoscope (VL) for airway management in pediatric patients with Pierre Robin syndrome (PRS) is insufficient. Therefore, the aim of this study was to compare the efficacy of the Glidescope® Core™ with a hyperangulated blade, the C-MAC® with a nonangulated Miller blade (C-MAC® Miller) and a conventional Miller laryngoscope when used by anesthetists with limited and extensive experience in simulated Pierre Robin sequence. METHODS: Forty-three anesthetists with limited experience and forty-three anesthetists with extensive experience participated in our randomized crossover manikin trial. Each performed endotracheal intubation with the Glidescope® Core™ with a hyperangulated blade, the C-MAC® with a Miller blade and the conventional Miller laryngoscope. "Time to intubate" was the primary endpoint. Secondary endpoints were "time to vocal cords", "time to ventilate", overall success rate, number of intubation attempts and optimization maneuvers, Cormack-Lehane score, severity of dental trauma and subjective impressions. RESULTS: Both hyperangulated and nonangulated VLs provided superior intubation conditions. The Glidescope® Core™ enabled the best glottic view, caused the least dental trauma and significantly decreased the "time to vocal cords". However, the failure rate of intubation was 14% with the Glidescope® Core™, 4.7% with the Miller laryngoscope and only 2.3% with the C-MAC® Miller when used by anesthetists with extensive previous experience. In addition, the "time to intubate", the "time to ventilate" and the number of optimization maneuvers were significantly increased using the Glidescope® Core™. In the hands of anesthetists with limited previous experience, the failure rate was 11.6% with the Glidescope® Core™ and 7% with the Miller laryngoscope. Using the C-MAC® Miller, the overall success rate increased to 100%. No differences in the "time to intubate" or "time to ventilate" were observed. CONCLUSIONS: The nonangulated C-MAC® Miller facilitated correct placement of the endotracheal tube and showed the highest overall success rate. Our results therefore suggest that the C-MAC® Miller could be beneficial and may contribute to increased safety in the airway management of infants with PRS when used by anesthetists with limited and extensive experience.

Incidence and Clinical Significance of Hyperkalemia Following Heart Transplantation.

BACKGROUND: Hyperkalemia (HK) is a life-threatening complication following solid organ transplantation, and patients often need potassium-chelating agents and deviations from standard posttransplant protocols. This is the first study to report the incidence and clinical impact of hyperkalemia following heart transplantation. METHODS: We retrospectively included patients who underwent heart transplantation at our institution between April 2014 and December 2018. Patients with multiorgan transplantation were excluded. Clinical outcomes of patients who had serum potassium >5.5 mEq/L in the first year posttransplant (HK group) were compared to patients who did not have serum potassium >5.5 mEq/L in the first year posttransplant (non-HK group). RESULTS: A total of 143 patients were included in this study. During the first year posttransplant, cumulative incidence of serum potassium >5.0, >5.5, and >6.0 mEq/L was 96%, 63%, and 24%, respectively. Fifty-five percent of patients required treatment with potassium-chelating agents. Sulfamethoxazole-trimethoprim was discontinued because of HK in 39% of patients. Overall survival of patients in the HK group (n = 89) was comparable to that of patients in the non-HK group (n = 54, 91% vs 98% at 1 year, P = .19), whereas infection-free survival was significantly lower in the HK group (34% vs 53% at 1 year, P = .010). Multivariate analysis revealed pretransplant renal dysfunction (odds ratio = 2.62; 95% confidence interval, 1.18-5.80; P = .018) and use of mechanical circulatory support (odds ratio = 2.90; 95% confidence interval, 1.08-7.76; P = .035) as significant predictors of posttransplant hyperkalemia. CONCLUSIONS: The incidence of HK following heart transplantation was high, with more than half of patients requiring any therapeutic interventions, and HK was related to an increase in infection events.