Citations

Background Medication nonadherence has been associated with poor outcomes in transplant recipients yet identifying these behaviors pre-transplant remains challenging. The simplified medication adherence questionnaire (SMAQ) is a brief, reliable instrument to assess medication adherence. The aim of this study was to perform SMAQ testing on thoracic organ candidates and examine correlations between these scores and individual patient factors predicting medication nonadherence. Methods Consenting waitlisted lung, heart, and heart-lung transplant candidates from six thoracic transplant centers were mailed a survey that included demographic information and the Simplified Medication Adherence Questionnaire (SMAQ). Univariate logistic regression analysis was performed to assess association between pre-transplant medication adherence and demographic characteristics, psychosocial factors, and mortality. Results Among 298 participants, 60.7% were medication nonadherent. Nonadherence was associated with some college education (OR: 1.73; CI: 1.06, 2.81), lower positive affect (OR: 0.95; CI: 0.92, 0.99), and higher uncertainty (OR: 1.02; CI: 1.01, 1.04). Higher positivity ratio predicted adherence. Conclusion Identifiable patient-specific characteristics associated with medication nonadherence can be screened for during thoracic transplant evaluation. Interventions aimed at improving these factors during the pre-transplant period may improve clinical post-transplant outcomes, however, larger studies are needed to validate these findings.

Background. Acute cellular rejection (ACR) remains a major cause of morbidity after heart transplantation despite advances in immunosuppression. Whole genome transcriptomic profiling offers a systems-based, unbiased approach to elucidate the molecular mechanisms underlying ACR. However, noninvasive, longitudinal biomarker assessments capable of capturing the temporal dynamics of rejection biology remain scarce. Methods. RNA sequencing of peripheral blood from heart transplant recipients before, during, and after ACR was compared with nonrejection controls. Pathway analysis was conducted using differentially expressed genes (DEGs), and a machine learning approach was applied to assess gene-based prediction of ACR. Results. A total of 235 rejection-specific significant DEGs and 863 postrejection DEGs (false discovery rate < 0.05) were identified. During ACR, DEGs were enriched for T-cell activation/differentiation, apoptosis, and B-cell receptor signaling pathways. By combining the 2 sets of DEGs, a panel of 71 common genes was identified that reflected the significant, longitudinal transcriptomic dynamics of ACR. In an elastic net machine learning–based classifier, DYNLL1 and SERF2 were identified as ACR predictive genes, and achieved a cross-validated area under the receiver operating characteristic curve of 0.63. Conclusions. Peripheral blood transcriptomics identify dynamic temporal responses in ACR including T- and B-cell pathways with potential ACR predictive genes that warrant further investigation.

Abstract The expanding use of continuous‐flow left ventricular assist devices (CF‐LVADs) for end‐stage heart failure warrants familiarity with the physiologic interaction of the device with the native circulation. Contemporary devices utilize predominantly centrifugal flow and, to a lesser extent, axial flow rotors that vary with respect to their intrinsic flow characteristics. Flow can be manipulated with adjustments to preload and afterload as in the native heart, and ascertainment of the predicted effects is provided by differential pressure‐flow ( H ‐ Q ) curves or loops. Valvular heart disease, especially aortic regurgitation, may significantly affect adequacy of mechanical support. In contrast, atrioventricular and ventriculoventricular timing is of less certain significance. Although beneficial effects of device therapy are typically seen due to enhanced distal perfusion, unloading of the left ventricle and atrium, and amelioration of secondary pulmonary hypertension, negative effects of CF‐LVAD therapy on right ventricular filling and function, through right‐sided loading and septal interaction, can make optimization challenging. Additionally, a lack of pulsatile energy provided by CF‐LVAD therapy has physiologic consequences for end‐organ function and may be responsible for a series of adverse effects. Rheological effects of intravascular pumps, especially shear stress exposure, result in platelet activation and hemolysis, which may result in both thrombotic and hemorrhagic consequences. Development of novel solutions for untoward device‐circulatory interactions will facilitate hemodynamic support while mitigating adverse events. © 2021 American Physiological Society. Compr Physiol 12:1‐37, 2021.

Abstract Heart transplantation (HT) is one of the prodigious achievements in modern medicine and remains the cornerstone in the treatment of patients with advanced heart failure. Advances in surgical techniques, immunosuppression, organ preservation, infection control, and allograft surveillance have improved short‐ and long‐term outcomes thereby contributing to greater clinical success of HT. However, prolonged allograft and patient survival following HT are still largely restricted by the development of late complications, including allograft rejection, infection, cardiac allograft vasculopathy (CAV), and malignancy. The introduction of mTOR inhibitors early after HT has demonstrated multiple protective effects against CAV progression, renal dysfunction, and tumorigenesis. Therefore, several HT programs increasingly use mTOR inhibitors with partial or complete withdrawal of calcineurin inhibitor (CNI) in stable HT patients to reduce complications risk and improve long‐term outcomes. Furthermore, despite a substantial improvement in exercise capacity and health‐related quality of life after HT as compared to advanced heart failure patients, most HT recipients remain with a 30% to 50% lower peak oxygen consumption (Vo 2 ) than that of age‐matched healthy subjects. Several factors, including alterations in central hemodynamics, HT‐related complications and alterations in the musculoskeletal system, and peripheral physiological abnormalities, presumably contribute to the reduced exercise capacity following HT. Cardiac denervation and subsequent loss of sympathetic and parasympathetic regulation are responsible for various physiological alterations in the cardiovascular system, which contributes to restricted exercise tolerance. Restoration of cardiac innervation may improve exercise capacity and quality of life, but the reinnervation process is only partial even several years after HT. Multiple studies have shown that aerobic and strengthening exercise interventions improve exercise capacity by increasing maximal heart rate, chronotropic response, and peak Vo 2 after HT. Novel exercise modalities, such as high‐intensity interval training (HIT), have been proven as safe and effective for further improvement in exercise capacity, including among de novo HT recipients. Further developments have recently emerged, including donor heart preservation techniques, noninvasive CAV and rejection surveillance methods, and improvements in immunosuppressive therapies, all aiming at increasing donor availability and improving late survival after HT. © 2023 American Physiological Society. Compr Physiol 13:4719‐4765, 2023.

ABSTRACT Background Addition of left heart catheterization (LHC) to exercise protocols allows for a unique focus on parameters of systolic and diastolic responses to increased activity in patients with left ventricular assist device (LVAD) support. Methods A retrospective review was conducted of all consecutive adult patients who underwent LHC with exercise for any indication from June 2017 to June 2023. For all patients, the relationship between exercise and parameters of LV systolic and diastolic response was assessed. Patients were divided into two cohorts based on the indication for testing: hemodynamic optimization (Optim, n = 5) or weaning consideration (Wean, n = 3). Results Eight patients (88% male, median age 57 years (IQR 44, 65)) were included. LVEF was 45% (IQR 45, 56) in Wean and 25% (IQR 20, 42) in Optim. LV systolic work index (LVSWI) increased more rapidly over levels of exercise in Wean vs. Optim (slope 46.3 vs. −0.625; p = 0.044) and LVSWI rose more quickly at lower levels of LV end diastolic pressure (LVEDP) in Wean vs. Optim (slope 219.5 vs. −2.008; p = 0.0026). Pulse power index was higher in Wean patients at baseline (0.046 (IQR 0.04, 0.07) vs. 0.016 (IQR 0.001, 0.04); p = 0.14) and peak exercise (0.12 (IQR 0.12, 0.12) vs. 0.06 (IQR 0.03, 0.1); p = 0.29). Conclusions Patients with favorable remodeling on LVAD support have significantly improved LV systolic and diastolic responses to exercise and a trend of higher systemic pulsatility. Improving our understanding of LV‐LVAD interactions with activity may aid in future efforts to improve exercise tolerance through speed modulation.

AbstractBackgroundThe prognosis in patients with advanced cardiac amyloidosis (CA) remains poor.ObjectivesWe sought to describe survival post heart transplantation (HT) in amyloid compared with non‐amyloid recipients, highlight waitlist times within the new allocation system across three Organ Procurement and Transplantation Network (OPTN) regions, and describe multiorgan transplantation (MOT) in hereditary amyloidosis.MethodsThis is a retrospective review of end‐stage CA patients who underwent HT at Mayo Clinic from January 2007 to December 2020. Wait time was compared in the new versus old OPTN allocation era starting December 18, 2018 by Wilcoxon rank sum test. All‐cause mortality for those with and without CA was compared using Kaplan–Meier estimates with log rank analysis, censoring December 16, 2022.ResultsFifty‐five patients with CA underwent HT between 2007 and 2020, 8 light chain amyloidosis (AL) (14.5%), 28 hereditary transthyretin (ATTRv) (50.9%), 17 wildtype transthyretin (ATTRwt) (30.9%), and 2 hereditary apolipoprotein A1 (AApoA1) amyloidosis patients (3.6%). No significant difference in overall survival post‐transplant was seen in amyloid compared with non‐amyloid (p = 0.816). Median time to HT was shorter in the new system, 45 days (IQR 24, 78) versus 174 days (IQR 76.5, 483.5), p = 0.006. There was a decline in MOT in hereditary amyloidosis over time with the concomitant rise in disease‐targeted therapies.ConclusionsHT survival in CA patients was similar to non‐amyloid patients. The new allocation system benefits this cohort with shorter wait times. There is less MOT in hereditary amyloidosis with increased utilization of disease‐targeted therapy.

Abstract Introduction Cardiopulmonary exercise testing (CPET) parameters such as peak VO2 ≤ 14ml/kg/min, percentage predicted peak VO2 (ppVO2) ≤ 50% and ventilation equivalent of carbon dioxide (Ve/VCO2) &gt;35 l/min/l/min are recommended thresholds to list for isolated heart transplant. There is minimal data on clinical events after listing to guide clinical management or priority in organ allocation. Purpose To assess the effect of peak VO2, ppVO2, Ve/VCO2 on clinical events after listing for isolated heart transplant. Methods In a single centre retrospective study, we identified patients who were status 6 or status 2 prior to 2018 at time of listing for isolated heart transplant between 2007 and 2021. Clinical data were collected by chart review. Primary outcome of progressive heart failure was defined as death or upgrade in transplant priority status (new inotropes or mechanical circulatory support). Comparison was made between peak VO2 strata (&gt; 14 vs ≤ 14 ml/kg/min), ppVO2 strata (&gt; 50% vs 40-50% vs &lt;40%) and Ve/VCO2 strata (&lt;35 vs &gt;35 l/min/l/min). Secondary outcome was time dependent survival after listing for heart transplant. Results We identified 141 patients of which 133 underwent CPET and follow up was available for 130 who were included in the analysis. Median age was 53 years (interquartile range 41-59 years), 29.1% of patients were female. Median peak VO2 was 14.0 ml/kg/min (11.2-15.7), ppVO2 was 44% (36-52), Ve/VCO2 slope was 34.0 (31.0-37.0) and RER was 1.1 (1.1-1.2). 87 patients had progressive heart failure consisting of 34 deaths and 83 patients having upgrade in priority status. There was a significant difference in risk of progressive heart failure comparing peak VO2 strata (Figure 1) (freedom from event at one year 71.4% with peak VO2 &gt; 14 vs 46.5% with peak VO2 ≤ 14, p=0.00061) and ppVO2 strata (Figure 2) (freedom from event at one year 75.0% with ppVO2 &gt;50% vs 61.2% with ppVO2 40-50% vs 42.6% with ppVO2 &lt;40%, p=0.0015). There was no significant difference with Ve/VCO2 strata (freedom from event at one year 59.8% with Ve/VCO2 &lt;34 vs 54.9% with Ve/VCO2 &gt;34, p=0.52). There were 34 deaths before transplant and 23 deaths after transplant. 87 patients underwent transplant. In a time dependent survival analysis, age, gender and ppVO2&lt;50% (HR 1.65 (0.87-3.12)) were not significant predictors of mortality. Both early transplant (defined as &lt; 1 year after listing, HR 0.14 (0.06-0.34) and late transplant (defined as &gt; 1 year after listing, HR 0.16 (0.08-0.32)) were significant predictors of lower mortality whilst Ve/VCO2&gt;35 (HR 2.09 (1.19-3.68)) was a significant predictor of higher mortality. Conclusions Peak VO2 and ppVO2 stratify risk of progressive heart failure in ambulatory patients awaiting isolated heart transplant. However, Ve/VCO2 is a predictor of significantly higher mortality. These findings should affect clinical management and transplant priority status; and influence revision of future guidelines.Freedom from event by peak VO2 strataFreedom from event by ppVO2 strata

Abstract Background It has been hypothesized that combined heart and kidney transplantation (HKT) may lead to immune modulation and attenuation of cardiac allograft vasculopathy (CAV) progression. Sirolimus (SRL) has been shown to mitigate the progression of CAV and confer renal protection. With the increasing use of SRL as primary immunosuppression in heart transplant (HT) recipients, the effect of HKT on CAV progression compared to HT-only remains undetermined. Purpose We sought to investigate the patterns of conversion from calcineurin inhibitors (CNI) to SRL, and its impact on CAV progression and outcomes in HKT compared to HT-only in a cohort with frequent use of SRL as primary immunosuppression. Methods A cohort of 302 patients who underwent either HT only (n=262) or combined HKT (n=40) was analyzed. CAV progression was assessed by measuring the delta (Δ) annual change in plaque volume (PV) normalized to vessel length (PV/VL in mm3/mm) and plaque index (PI) (%) (calculated as the PV to VV ratio) between baseline and last follow-up coronary intravenous ultrasound (IVUS). Clinical adverse outcomes included all-cause death and CAV-associated events. Secondary outcomes included differences in renal function and incidence of SRL-associated proteinuria (defined as Δ urine protein ≥300 mg/24 h at 1 year after conversion to SRL) between HT-only and HKT recipients. Results Overall, 217 (72%) patients were converted from CNI to SRL as primary immunosuppression. HT recipients were more likely to be converted to SRL than combined HKT recipients (74% vs. 55%, P=0.01). HKT was associated with significantly higher ΔPV/VL (P=0.01) and a trend toward a higher ΔPI (P=0.06) than HT-only, but this association was markedly attenuated after adjustment to SRL conversion. HKT was associated with similar risk of death (adjusted hazard ratio [HR] 0.69, 95%CI: 0.28-1.71, P=0.43) and CAV-related events (adjusted HR 0.83, 95% CI: 0.30-2.31, P=0.72). Conversion to SRL was significantly associated with decreased risk of death and CAV-related events in the overall cohort. This association was not modified by the type of organ transplantation (Pinteraction=NS), and without a significant effect on estimated glomerular filtration rate (eGFR) or proteinuria. Conclusions HKT recipients compared to HT-only were less likely to be converted from CNI to SRL-based immunosuppression and had a greater CAV progression but without significant differences in all-cause mortality or CAV-related events. The clinical benefit and safety of conversion to SRL appeared similar in the HKT and isolated HT cohorts.

Abstract Background In light of the updated lowered threshold for diagnosing pulmonary hypertension (PH), the reversibility of precapillary PH with left ventricular assist device (LVAD) and the associated post heart transplantation (HT) outcomes remain unclear. Purpose and methods Using data from the United Network for Organ Sharing database, we aimed to investigate predictors of persistent precapillary PH in HT recipients bridged with LVAD, and examine the interrelated post-HT survival, using the updated pulmonary vascular resistance (PVR) cutoff of &gt;2 WU for precapillary PH. Results Among 2169 HT recipients bridged with LVAD, 1299 had PVR&gt;2 at baseline; 551 (42.4%) of whom normalized their PVR≤2 and 748 (57.6%) remained with elevated PVR&gt;2 after LVAD implantation. Female sex (adjusted odds ratio [aOR] 2.22, 95% confidence interval [CI]:1.61-3.07, p&lt;0.001) and inotropes-treatment at-listing (aOR 1.31, 95% CI: 1.03-1.66, p=0.028) were associated with persistently elevated PVR post LVAD. Conversely, longer duration of LVAD support (aOR 0.74, 95% CI: 0.65-.84, p&lt;0.001) and use of HeartMate 2 (aOR 0.74, CI: 0.59-0. 93, p=0.011) were protective against persistently elevated PVR post-LVAD. Persistently elevated PVR &gt;2 post-LVAD was associated with increased risk of death compared to those who normalized their PVR (adjusted hazard ratio [aHR] 1.26, 95% CI: 1.01-1.57, p=0.037). However, normalized PVR post-LVAD group had comparable survival to those with PVR≤2 at baseline (aHR 0.76, 95% CI: 0.57-1.02, p=0.07). Conclusions Many HT recipients bridged with LVAD remain with PVR&gt;2 post-LVAD implantation, which is associated with increased risk of death post-HT compared to patients with normalized PVR post-LVAD.

Introduction: Advanced age is a risk factor for poor outcomes following left ventricular assist device (LVAD) implant. A means of identifying elderly patients with acceptable mortality risk following LVAD surgery is not currently available. The HeartMate II (HMII) Risk Score (HMRS) was recently developed and validated, providing good risk discrimination for predicting survival in patients undergoing HMII implant. Independent survival predictors in the model included age and markers of renal function, coagulopathy and nutrition. We hypothesize that the HMRS will provide utility for risk stratification of the elderly LVAD candidate. Methods: Elderly patients (age >65 years) enrolled into the HMII Destination Therapy (DT) and Bridge to Transplant trials were selected for the study (n=444). Complete data for HMRS calculation was available in 98% (n=435). Preoperative patient HMRS was calculated according to the formula: HMRS = ln(1.29)*decade of age + ln(0.71)*Albumin + ln(1.37)*Cr + ln(1.86)*INR + ln(0.52)*LVAD Center Volume >=15 + ln(0.67)*Implant after 2007. Patients were trichotimized into high (HMRS >1.0), medium (HMRS 0.50-1.0), and low (HMRS <=0.50) risk categories (as previously defined in model development) based on HMRS. The primary endpoint was survival at 1 year following LVAD implant, estimated using Kaplan-Meier methods. Results: The mean cohort age was 71±4 years and 84% (n=372) had devices implanted for DT. The table shows the HMRS along with mean±stddev values for the score's components. All between-group differences were statistically significant (Kruskal-Wallis p<0.05), although differences in age were not clinically significant. Survival based on HMRS strata is shown in the figure. Patients in the low and medium risk groups had survivals >80% at 1 year following LVAD implant. Conclusions: The HMRS can be used to identify elderly patients with survivals comparable to that of the general LVAD population.