Preoperative Amiodarone and Primary Graft Dysfunction in Heart Transplantation.

BACKGROUND: Preoperative amiodarone effects on postorthotopic heart transplant (OHT) outcomes remain controversial. OBJECTIVE: The purpose of this study was to determine the effect of cumulative pre-OHT amiodarone exposure on severe primary graft dysfunction (PGD). METHODS: We retrospectively reviewed adult OHT recipients between August 2012 and June 2018. Primary outcome was severe PGD in patients receiving amiodarone at 3, 6, and 12 months prior to OHT compared with those not receiving amiodarone. Secondary outcomes included intensive care unit (ICU) and hospital length of stay, duration of mechanical ventilation, early graft failure (EGF), mortality at 3, 6, and 12 months post-OHT, and 30-day incidence of postoperative tachyarrhythmias, bradycardia, permanent pacemaker implantation, and rejection. RESULTS: Incidence of severe PGD was 12.5% in those who received amiodarone compared to 6.8% in those who did not (14 vs 6, P = 0.18). Cumulative preoperative amiodarone significantly increased the odds of severe PGD at 3 months (odds ratio [OR]: 1.03; 95% confidence interval [CI]: 1.001-1.06; P = 0.044) and 6 months (OR: 1.02, 95% CI: 1.003-1.044; P = 0.024) in a multivariate logistic regression. Patients on amiodarone had significantly higher rates of postoperative bradycardia (13.4% vs 4.5%, P = 0.03). CONCLUSION AND RELEVANCE: A trend toward increased PGD was present in patients receiving preoperative amiodarone. This finding combined with the regression showing significantly increased odds of PGD with increasing 3 and 6 month cumulative amiodarone dose is clinically concerning. Escalation of care with pacemaker implantation was required more frequently in patients on pre-OHT amiodarone.

Utilization of Paragonix Sherpapak Cardiac Transport System for the Preservation of Donor Hearts After Circulatory Death.

BACKGROUND: Donation after circulatory death (DCD) heart transplantation is being increasingly adopted by transplant centers. The optimal method of DCD heart preservation during transport after in situ thoracoabdominal normothermic regional perfusion (TA-NRP) is not known. METHODS: We evaluated our experience with the Paragonix SherpaPak Cardiac Transport System (SCTS) for the transport of DCD cardiac allografts after TA-NRP recovery between January 2021 and December 2022. We collected and evaluated donor characteristics, allograft ischemic intervals, and recipient baseline demographic and clinical variables, and short-term outcomes. RESULTS: Twelve recipients received DCD grafts recovered with TA-NRP and transported in SCTS during the study period. The median age of 10 male and 2 female donors was 32 years (min 15, max 38). The median duration of functional warm ischemia was 12 minutes (min 8, max 22). Hearts were preserved in SCTS for a median of 158 minutes (min 37, max 224). Median recipient age was 61 years (min 28, max 70). Ten recipients (83%) survived to hospital discharge, with one death attributable to graft dysfunction (8%). The median vasoactive-inotropic (VIS) score at 72 hours post-transplantation of the entire cohort was 6 (min 0, max 15). The median length of intensive care unit stay in hospital survivors was 5 days (min 3, max 17) days and hospital stay 17 days (min 9, max 37). CONCLUSIONS: The Paragonix SCTS provides efficacious preservation of DCD grafts for ≥3.5 hours. Organs transported with this device showed satisfactory post-transplantation function.

Genetic Architecture of Dilated Cardiomyopathy in Individuals of African and European Ancestry.

Importance: Black patients with dilated cardiomyopathy (DCM) have increased familial risk and worse outcomes than White patients, but most DCM genetic data are from White patients. Objective: To compare the rare variant genetic architecture of DCM by genomic ancestry within a diverse population of patients with DCM. Design: Cross-sectional study enrolling patients with DCM who self-identified as non-Hispanic Black, Hispanic, or non-Hispanic White from June 7, 2016, to March 15, 2020, at 25 US advanced heart failure programs. Variants in 36 DCM genes were adjudicated as pathogenic, likely pathogenic, or of uncertain significance. Exposure: Presence of DCM. Main Outcomes and Measures: Variants in DCM genes classified as pathogenic/likely pathogenic/uncertain significance and clinically actionable (pathogenic/likely pathogenic). Results: A total of 505, 667, and 26 patients with DCM of predominantly African, European, or Native American genomic ancestry, respectively, were included. Compared with patients of European ancestry, a lower percentage of patients of African ancestry had clinically actionable variants (8.2% [95% CI, 5.2%-11.1%] vs 25.5% [95% CI, 21.3%-29.6%]), reflecting the lower odds of a clinically actionable variant for those with any pathogenic variant/likely pathogenic variant/variant of uncertain significance (odds ratio, 0.25 [95% CI, 0.17-0.37]). On average, patients of African ancestry had fewer clinically actionable variants in TTN (difference, -0.09 [95% CI, -0.14 to -0.05]) and other genes with predicted loss of function as a disease-causing mechanism (difference, -0.06 [95% CI, -0.11 to -0.02]). However, the number of pathogenic variants/likely pathogenic variants/variants of uncertain significance was more comparable between ancestry groups (difference, -0.07 [95% CI, -0.22 to 0.09]) due to a larger number of non-TTN non-predicted loss of function variants of uncertain significance, mostly missense, in patients of African ancestry (difference, 0.15 [95% CI, 0.00-0.30]). Published clinical case-based evidence supporting pathogenicity was less available for variants found only in patients of African ancestry (P < .001). Conclusion and Relevance: Patients of African ancestry with DCM were less likely to have clinically actionable variants in DCM genes than those of European ancestry due to differences in genetic architecture and a lack of representation of African ancestry in clinical data sets.

Rare Variant Genetics and Dilated Cardiomyopathy Severity: The DCM Precision Medicine Study.

BACKGROUND: Dilated cardiomyopathy (DCM) can lead to advanced disease, defined herein as necessitating a durable left ventricular assist device or a heart transplant (LVAD/HT). DCM is known to have a genetic basis, but the association of rare variant genetics with advanced DCM has not been studied. METHODS: We analyzed clinical and genetic sequence data from patients enrolled between 2016 and 2021 in the US multisite DCM Precision Medicine Study, which was a geographically diverse, multiracial, multiethnic cohort. Clinical evaluation included standardized patient interview and medical record query forms. DCM severity was classified into 3 groups: patients with advanced disease with LVAD/HT; patients with an implantable cardioverter defibrillator (ICD) only; or patients with no ICD or LVAD/HT. Rare variants in 36 DCM genes were classified as pathogenic or likely pathogenic or variants of uncertain significance. Confounding factors we considered included demographic characteristics, lifestyle factors, access to care, DCM duration, and comorbidities. Crude and adjusted associations between DCM severity and rare variant genetic findings were assessed using multinomial models with generalized logit link. RESULTS: Patients' mean (SD) age was 51.9 (13.6) years; 42% were of African ancestry, 56% were of European ancestry, and 44% were female. Of 1198 patients, 347 had LVAD/HT, 511 had an ICD, and 340 had no LVAD/HT or ICD. The percentage of patients with pathogenic or likely pathogenic variants was 26.2%, 15.9%, and 15.0% for those with LVAD/HT, ICD only, or neither, respectively. After controlling for sociodemographic characteristics and comorbidities, patients with DCM with LVAD/HT were more likely than those without LVAD/HT or ICD to have DCM-related pathogenic or likely pathogenic rare variants (odds ratio, 2.3 [95% CI, 1.5-3.6]). The association did not differ by ancestry. Rare variant genetic findings were similar between patients with DCM with an ICD and those without LVAD/HT or ICD. CONCLUSIONS: Advanced DCM was associated with higher odds of rare variants in DCM genes adjudicated as pathogenic or likely pathogenic, compared with individuals with less severe DCM. This finding may help assess the risk of outcomes in management of patients with DCM and their at-risk family members. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03037632.

Screening for Dilated Cardiomyopathy in At-Risk First-Degree Relatives.

BACKGROUND: Cardiovascular screening is recommended for first-degree relatives (FDRs) of patients with dilated cardiomyopathy (DCM), but the yield of FDR screening is uncertain for DCM patients without known familial DCM, for non-White FDRs, or for DCM partial phenotypes of left ventricular enlargement (LVE) or left ventricular systolic dysfunction (LVSD). OBJECTIVES: This study examined the yield of clinical screening among reportedly unaffected FDRs of DCM patients. METHODS: Adult FDRs of DCM patients at 25 sites completed screening echocardiograms and ECGs. Mixed models accounting for site heterogeneity and intrafamilial correlation were used to compare screen-based percentages of DCM, LVSD, or LVE by FDR demographics, cardiovascular risk factors, and proband genetics results. RESULTS: A total of 1,365 FDRs were included, with a mean age of 44.8 ± 16.9 years, 27.5% non-Hispanic Black, 9.8% Hispanic, and 61.7% women. Among screened FDRs, 14.1% had new diagnoses of DCM (2.1%), LVSD (3.6%), or LVE (8.4%). The percentage of FDRs with new diagnoses was higher for those aged 45 to 64 years than 18 to 44 years. The age-adjusted percentage of any finding was higher among FDRs with hypertension and obesity but did not differ statistically by race and ethnicity (16.2% for Hispanic, 15.2% for non-Hispanic Black, and 13.1% for non-Hispanic White) or sex (14.6% for women and 12.8% for men). FDRs whose probands carried clinically reportable variants were more likely to be identified with DCM. CONCLUSIONS: Cardiovascular screening identified new DCM-related findings among 1 in 7 reportedly unaffected FDRs regardless of race and ethnicity, underscoring the value of clinical screening in all FDRs.

Effectiveness of the Family Heart Talk Communication Tool in Improving Family Member Screening for Dilated Cardiomyopathy: Results of a Randomized Trial.

BACKGROUND: Managing disease risk among first-degree relatives of probands diagnosed with a heritable disease is central to precision medicine. A critical component is often clinical screening, which is particularly important for conditions like dilated cardiomyopathy (DCM) that remain asymptomatic until severe disease develops. Nonetheless, probands are frequently ill-equipped to disseminate genetic risk information that motivates at-risk relatives to complete recommended clinical screening. An easily implemented remedy for this key issue has been elusive. METHODS: The DCM Precision Medicine Study developed Family Heart Talk, a booklet designed to help probands with DCM communicate genetic risk and the need for cardiovascular screening to their relatives. The effectiveness of the Family Heart Talk booklet in increasing cardiovascular clinical screening uptake among first-degree relatives was assessed in a multicenter, open-label, cluster-randomized, controlled trial. The primary outcome measured in eligible first-degree relatives was completion of screening initiated within 12 months after proband enrollment. Because probands randomized to the intervention received the booklet at the enrollment visit, eligible first-degree relatives were limited to those who were alive the day after proband enrollment and not enrolled on the same day as the proband. RESULTS: Between June 2016 and March 2020, 1241 probands were randomized (1:1) to receive Family Heart Talk (n=621) or not (n=620) within strata defined by site and self-identified race/ethnicity (non-Hispanic Black, non-Hispanic White, or Hispanic). Final analyses included 550 families (n=2230 eligible first-degree relatives) in the Family Heart Talk arm and 561 (n=2416) in the control arm. A higher percentage of eligible first-degree relatives completed screening in the Family Heart Talk arm (19.5% versus 16.0%), and the odds of screening completion among these first-degree relatives were higher in the Family Heart Talk arm after adjustment for proband randomization stratum, sex, and age quartile (odds ratio, 1.30 [1-sided 95% CI, 1.08-∞]). A prespecified subgroup analysis did not find evidence of heterogeneity in the adjusted intervention odds ratio across race/ethnicity strata (P=0.90). CONCLUSIONS: Family Heart Talk, a booklet that can be provided to patients with DCM by clinicians with minimal additional time investment, was effective in increasing cardiovascular clinical screening among first-degree relatives of these patients. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03037632.

Impact of donation after circulatory death heart transplantation on waitlist outcomes and transplantation activity.

INTRODUCTION: Donation after circulatory death (DCD) heart transplantation has been shown to have comparable outcomes to transplantation using brain death donors (DBDs). This study evaluates the impact of this alternative source of allografts on waitlist mortality and transplant volume. METHODS: We compared waitlist mortality and transplant rates in patients who were registered before (2019 period) and after we adopted DCD heart transplantation (2021 period). RESULTS: We identified 111 patients who were on the waiting list in 2019 and 77 patients who were registered during 2021. Total number of donor organ offers received in 2019 was 385 (178 unique donors) versus 3450 (1145 unique donors) in 2021. More than 40% of all donors in 2021 were DCDs. Waitlist mortality was comparable for patients in 2019 and 2021 (18/100 person-years in 2019 vs. 26/100 person-years in 2021, p = .49). The transplant rate was 67/100 person-years in 2019 versus 207/100 person-years in 2021 (p < .001). After adjusting for acuity status, gender, blood type, and weight, patients listed in 2021 had 2.08 times greater chance of transplantation compared to patients listed in 2019 (HR 2.08, 95% confidence interval [CI] 1.26-3.45, p = .004). CONCLUSIONS: Use of DCD donor hearts significantly increased heart transplant rate in our institution.

The role of a multidisciplinary heart failure clinic in optimization of guideline-directed medical therapy: HF-optimize.

BACKGROUND: Guideline-directed medical therapy (GDMT) reduces mortality and hospitalizations in adults with heart failure with reduced ejection fraction (HFrEF); however, few are receiving GDMT. National registries show as few as 1% of patients are receiving appropriate GDMT. Development of heart failure clinics achieving optimal GDMT are crucial to improve outcomes for HFrEF patients. OBJECTIVE: We developed a multidisciplinary HF-Optimize clinic aimed at improving GDMT use along with providing education, resources, and comorbidity screening for adults with HFrEF. METHODS: We targeted patients with newly diagnosed HFrEF and/or recent or multiple admissions for 6 visits over 12 weeks. We measured medication use, ejection fraction, 6-minute walk test distance, and health-related quality of life (EuroQol Visual Analog Scale) at visits 1 and 6. RESULTS: One-hundred ten patients completed all visits. Patients were a mean age of 58 (±14) years, 37% were female, and 42% were of non-White race. From visit 1 to visit 6, utilization of GDMT increased from 35.5% to 85.5% (p < 0.001) and significant improvements in ejection fraction (25.9% to 35.5%, p < 0.001), 6-minute walk distance (1032 feet to 1121.7 feet, p = 0.001), and quality of life (63.8/100 vs 70.8/100, p = 0.002). Only 2 patients (1.8%) that completed HF-Optimize had a 30-day heart failure readmission. CONCLUSION: Our multidisciplinary HF-Optimize clinic improved medication usage and clinical outcomes. Further studies are needed to validate outcomes of multidisciplinary GDMT clinics.

Impact of digoxin utilization on clinical outcomes following left ventricular assist device implantation.

INTRODUCTION: We aimed to assess the impact of digoxin use following left ventricular assist device (LVAD) implantation on clinical outcomes. METHODS: Patients implanted with continuous flow LVADs at a single academic medical center and survived to initial hospital discharge were included in the analysis (n = 346). Clinical events were captured at a maximum of 2 years of follow up. Digoxin use was defined as 30-day continuous use post-LVAD. Negative binomial regression and Kaplan-Meier method were used to assess the association between digoxin use and clinical outcomes. RESULTS: Mean age of the cohort was 56 years (±13) and 23% (79/346) were female sex. Digoxin was used in 144 patients (41.6%) for a median of 268 days (IQR 154, 616). Digoxin use was associated with a significant reduction in cumulative incidence of gastrointestinal bleeding (GIB) (15% vs 26%, p = 0.004). After adjusting for age, hypertension, post-operative hemoglobin, RDW, potassium, and GFR, and use of angiotensin receptor/neprilysin inhibitor, there remained a significant 47% reduction in GIB incidence in patients treated with digoxin. There was no significant difference in cumulative incidence in right ventricular failure (RVF) between the two groups. There was no difference in overall 2-year survival between groups. CONCLUSIONS: Digoxin use was associated with reduction in GIB events, but not in RVF or mortality. Further studies are needed to confirm these findings and to investigate optimal timing and patient population.

Prevalence and Cumulative Risk of Familial Idiopathic Dilated Cardiomyopathy.

Importance: Idiopathic dilated cardiomyopathy (DCM) aggregates in families, and early detection in at-risk family members can provide opportunity to initiate treatment prior to late-phase disease. Most studies have included only White patients, yet Black patients with DCM have higher risk of heart failure-related hospitalization and death. Objective: To estimate the prevalence of familial DCM among DCM probands and the age-specific cumulative risk of DCM in first-degree relatives across race and ethnicity groups. Design, Setting, and Participants: A family-based, cross-sectional study conducted by a multisite consortium of 25 US heart failure programs. Participants included patients with DCM (probands), defined as left ventricular systolic dysfunction and left ventricular enlargement after excluding usual clinical causes, and their first-degree relatives. Enrollment commenced June 7, 2016; proband and family member enrollment concluded March 15, 2020, and April 1, 2021, respectively. Exposures: The presence of DCM in a proband. Main Outcomes and Measures: Familial DCM defined by DCM in at least 1 first-degree relative; expanded familial DCM defined by the presence of DCM or either left ventricular enlargement or left ventricular systolic dysfunction without known cause in at least 1 first-degree relative. Results: The study enrolled 1220 probands (median age, 52.8 years [IQR, 42.4-61.8]; 43.8% female; 43.1% Black and 8.3% Hispanic) and screened 1693 first-degree relatives for DCM. A median of 28% (IQR, 0%-60%) of living first-degree relatives were screened per family. The crude prevalence of familial DCM among probands was 11.6% overall. The model-based estimate of the prevalence of familial DCM among probands at a typical US advanced heart failure program if all living first-degree relatives were screened was 29.7% (95% CI, 23.5% to 36.0%) overall. The estimated prevalence of familial DCM was higher in Black probands than in White probands (difference, 11.3% [95% CI, 1.9% to 20.8%]) but did not differ significantly between Hispanic probands and non-Hispanic probands (difference, -1.4% [95% CI, -15.9% to 13.1%]). The estimated prevalence of expanded familial DCM was 56.9% (95% CI, 50.8% to 63.0%) overall. Based on age-specific disease status at enrollment, estimated cumulative risks in first-degree relatives at a typical US advanced heart failure program reached 19% (95% CI, 13% to 24%) by age 80 years for DCM and 33% (95% CI, 27% to 40%) for expanded DCM inclusive of partial phenotypes. The DCM hazard was higher in first-degree relatives of non-Hispanic Black probands than non-Hispanic White probands (hazard ratio, 1.89 [95% CI, 1.26 to 2.83]). Conclusions and Relevance: In a US cross-sectional study, there was substantial estimated prevalence of familial DCM among probands and modeled cumulative risk of DCM among their first-degree relatives. Trial Registration: ClinicalTrials.gov Identifier: NCT03037632.

Pulmonary Function Testing Pre-heart Transplant Predicts Posttransplant Survival.

Although pulmonary function testing (PFT) is typically performed for heart transplant evaluation, the prognostic utility of PFTs after transplantation is unknown. We evaluated whether PFT parameters were correlated with outcomes following heart transplantation. METHODS: International Society for Heart and Lung Transplantation Thoracic Organ Transplant Registry data were utilized. Survival was assessed using Kaplan-Meier method and compared via log-rank test. Cox proportional hazard modeling was used to evaluate univariate and multivariate predictors of survival. RESULTS: Eight hundred two patients pretransplant PFT data were available for evaluation. Forced expiratory volume in 1 s (FEV1) < 50% predicted (P < 0.0001), and forced vital capacity (FVC) < 50% predicted each had significantly higher mortality (P = 0.001) compared with patients with FEV1 or FVC 50%-80% or >80%. FEV1/FVC < 0.7 was not associated with increased mortality. FEV1 and FVC below 50% both predicted longer lengths of stay (P = 0.028 for FEV1 and P = 0.0075 for FVC). After adjusting for male gender, age, body mass index, smoking history, chronic obstructive pulmonary disease, creatinine, albumin, and total bilirubin, FEV1 < 50% (hazard ratio, 4.91; P < 0.0001; 95% confidence interval, 2.69-8.94) and FVC < 50% (hazard ratio, 2.75; P = 0.003; 95% confidence interval, 1.4-5.4) both remained independent predictors of mortality. CONCLUSIONS: Abnormal pulmonary function (FEV1 or FVC below 50% of predicted) pre-heart transplantation is associated with increased mortality and longer lengths of stay posttransplant.

Noninvasive Assessment of Cardiac Output: Accuracy and Precision of the Closed-Circuit Acetylene Rebreathing Technique for Cardiac Output Measurement.

Background Accurate assessment of cardiac output is critical to the diagnosis and management of various cardiac disease states; however, clinical standards of direct Fick and thermodilution are invasive. Noninvasive alternatives, such as closed-circuit acetylene (C2H2) rebreathing, warrant validation. Methods and Results We analyzed 10 clinical studies and all available cardiopulmonary stress tests performed in our laboratory that included a rebreathing method and direct Fick or thermodilution. Studies included healthy individuals and patients with clinical disease. Simultaneous cardiac output measurements were obtained under normovolemic, hypovolemic, and hypervolemic conditions, along with submaximal and maximal exercise. A total of 3198 measurements in 519 patients were analyzed (mean age, 59 years; 48% women). The C2H2 method was more precise than thermodilution in healthy individuals with half the typical error (TE; 0.34 L/min [r=0.92] and coefficient of variation, 7.2%) versus thermodilution (TE=0.67 [r=0.70] and coefficient of variation, 13.2%). In healthy individuals during supine rest and upright exercise, C2H2 correlated well with thermodilution (supine: r=0.84, TE=1.02; exercise: r=0.82, TE=2.36). In patients with clinical disease during supine rest, C2H2 correlated with thermodilution (r=0.85, TE=1.43). C2H2 was similar to thermodilution and nitrous oxide (N2O) rebreathing technique compared with Fick in healthy adults (C2H2 rest: r=0.85, TE=0.84; C2H2 exercise: r=0.87, TE=2.39; thermodilution rest: r=0.72, TE=1.11; thermodilution exercise: r=0.73, TE=2.87; N2O rest: r=0.82, TE=0.94; N2O exercise: r=0.84, TE=2.18). The accuracy of the C2H2 and N2O methods was excellent (r=0.99, TE=0.58). Conclusions The C2H2 rebreathing method is more precise than, and as accurate as, the thermodilution method in a variety of patients, with accuracy similar to an N2O rebreathing method approved by the US Food and Drug Administration.

Impact of temporary mechanical circulatory support for early graft failure on post-heart transplantation outcomes.

Although temporary mechanical circulatory support (tMCS) for hemodynamic failure following heart transplantation is associated with increased early morbidity and mortality, the impact of etiology of graft dysfunction and long-term clinical implications are less well known. The objective of our study was to evaluate outcomes in patients who required venoarterial extracorporeal membrane oxygenation (VA ECMO) or temporary right ventricular assist device (RVAD) support for either primary or secondary early graft dysfunction. Hospital mortality in 27 patients who required tMCS following heart transplantation at our institution between 2007 and 2017 was 56%, 30% in patients with right ventricular dysfunction secondary to increased afterload, 60% in patients with primary graft dysfunction, and 100% in patients with graft failure secondary to coagulopathy with intraoperative bleeding or overwhelming sepsis. Conditional 1-year and 5-year survival was comparable between patients with, and without, the need for post-transplantation support with tMCS (98% and 89%; 92% and 65% at 1 and 5 years, P = .21). Etiology of early graft failure plays an important part in determining the short-term post-heart transplantation outcome. Although complications associated with tMCS use, such as renal dysfunction and infection, extend beyond index transplant hospitalization, long-term conditional survival is not compromised.

Mechanisms of Chronotropic Incompetence in Heart Failure With Preserved Ejection Fraction.

BACKGROUND: Chronotropic incompetence is common in heart failure with preserved ejection fraction (HFpEF) and is associated with impaired aerobic capacity. We investigated the integrity of cardiac ß-receptor responsiveness, an important mechanism involved in exertional increases in HR, in HFpEF and control subjects. METHODS: Thirteen carefully screened patients with HFpEF and 13 senior controls underwent exercise testing and graded isoproterenol infusion to quantify cardiac ß-receptor-mediated HR responses. To limit autonomic neural influences on heart rate (HR) during isoproterenol, dexmedetomidine and glycopyrrolate were given. Isoproterenol doses were increased incrementally until HR increased by 30 beats per minute. Plasma levels of isoproterenol at each increment were measured by liquid chromatography with electrochemical detection and plotted against HR. RESULTS: Peak VO2 and HR (117±15 versus 156±15 beats per minute; P<0.001) were lower in HFpEF than senior controls. Cardiac ß-receptor sensitivity was lower in HFpEF compared to controls (0.156±0.133 versus 0.254±0.166 beats per minute/[isoproterenol ng/mL]; P<0.001). Seven of 13 HFpEF subjects had ß-receptor sensitivity similar to senior controls but still had lower peak HRs (122±14 versus 156±15 beats per minute; P<0.001). CONCLUSIONS: Contrary to our hypothesis, patients with HFpEF displayed impaired cardiac ß-receptor sensitivity compared with senior controls. In the 7 out of 13 patients with HFpEF with age-appropriate ß-receptor sensitivity, peak HR remained low, suggesting impaired sinus node ß-receptor function may not fully account for low exercise HR response. Rather in some patients with HFpEF, chronotropic incompetence might reflect premature cessation of exercise before maximal sinus node activation. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02524145.

Percutaneous Deactivation of Left Ventricular Assist Devices.

Left ventricular assist device (LVAD) deactivation may be considered in cases of left ventricular recovery, pump thrombosis, infection, and end-of-life palliation. Surgical pump explantation remains the principal method, but percutaneous deactivation presents a safe and effective alternative. We have developed a formal program for percutaneous LVAD deactivation within our advanced heart failure program including patient selection criteria, preprocedure testing, a procedural algorithm, and a postprocedure care plan. Patient selection for percutaneous LVAD deactivation required review by an interdisciplinary heart transplant team including reason for deactivation, cardiac function, surgical risk, and patient preference. All candidates underwent LVAD ramp studies with both transthoracic echocardiography and right heart catheterization assessment. Deactivation was performed under general anesthesia with transesophageal echocardiography guidance. Three Amplatzer Vascular Plug IIs (Abbott, St. Paul, MN) were deployed in the LVAD outflow cannula with the proximal edge of the third plug aligned with the aortic anastomosis of the graft as guided by angiography and 3-dimensional transesophageal echocardiography. In a separate procedure, the LVAD drive line was transected below the skin, which was closed surgically over the driveline stump. Anticoagulation was continued for at least 3 months. Since initiation in January 2017, our program has performed 7 percutaneous LVAD deactivation procedures. All procedures have been successful, 5 of the patients remain medically managed, and 2 have proceeded to heart transplant. Percutaneous LVAD deactivation provides an alternative to surgical explantation. A percutaneous LVAD deactivation program is an important component of an advanced heart failure program.

Recurrent pump thrombosis is common after axial continuous-flow left ventricular assist device exchange.

In selected patients with left ventricular assist device-associated infection or malfunction, pump exchange may become necessary after conservative treatment options fail and heart transplantation is not readily available. We examined the survival and complication rate in patients (⩾19 years of age) who underwent HeartMate II to HeartMate II exchange at our institution from 1 January 2010 to 28 February 2018. Clinical outcomes were analyzed and compared for patients who underwent exchange for pump thrombosis (14 patients), breach of driveline integrity (5 patients), and device-associated infection (2 patients). There were no differences in 30-day mortality (p = 0.58), need for temporary renal replacement therapy (p = 0.58), right ventricular mechanical support (p = 0.11), and postoperative stroke (p = 0.80) among groups. Survival at 1 year was 90% ± 7% for the whole cohort and 85% ± 10% for those who underwent exchange for pump thrombosis. In patients exchanged for device thrombosis, freedom from re-thrombosis and survival free from pump re-thrombosis at 1 year were 49% ± 16% and 42% ± 15%, respectively. No association of demographic and clinical variables with the risk of recurrent pump thrombosis after the first exchange was identified. Survival after left ventricular assist device exchange compares well with published results after primary left ventricular assist device implantation. However, recurrence of thrombosis was common among patients who required a left ventricular assist device exchange due to pump thrombosis. In this sub-group, consideration should be given to alternative strategies to improve the outcomes.

Does High-Intensity Endurance Training Increase the Risk of Atrial Fibrillation? A Longitudinal Study of Left Atrial Structure and Function.

BACKGROUND: Exercise mitigates many cardiovascular risk factors associated with atrial fibrillation. Endurance training has been associated with atrial structural changes which can increase the risk for atrial fibrillation. The dose of exercise training required for these changes is uncertain. We sought to evaluate the impact of exercise on left atrial (LA) mechanical and electrical function in healthy, sedentary, middle-aged adults. METHODS: Sixty-one adults (52±5 years) were randomized to either 10 months of high-intensity exercise training or yoga. At baseline and post-training, all participants underwent maximal exercise stress testing to assess cardiorespiratory fitness, P-wave signal-averaged electrocardiography for filtered P-wave duration and atrial late potentials (root mean square voltage of the last 20 ms), and echocardiography for LA volume, left ventricular end-diastolic volume, and mitral inflow for assessment of LA active emptying. Post-training data were compared with 14 healthy age-matched Masters athletes. RESULTS: LA volume, Vo2 max, and left ventricular end-diastolic volume increased in the exercise group (15%, 17%, and 16%, respectively) with no change in control (P<0.0001). LA active emptying decreased post-exercise versus controls (5%; P=0.03). No significant changes in filtered P-wave duration or root mean square voltage of the last 20 ms occurred after exercise training. LA and left ventricular volumes remained below Masters athletes. The athletes had longer filtered P-wave duration but no difference in the frequency of atrial arrhythmia. CONCLUSIONS: Changes in LA structure, LA mechanical function, and left ventricular remodeling occurred after 10 months of exercise but without significant change in atrial electrical activity. A longer duration of training may be required to induce electrical changes thought to cause atrial fibrillation in middle-aged endurance athletes. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique Identifier: NCT02039154.

Reversing the Cardiac Effects of Sedentary Aging in Middle Age-A Randomized Controlled Trial: Implications For Heart Failure Prevention.

BACKGROUND: Poor fitness in middle age is a risk factor for heart failure, particularly heart failure with a preserved ejection fraction. The development of heart failure with a preserved ejection fraction is likely mediated through increased left ventricular (LV) stiffness, a consequence of sedentary aging. In a prospective, parallel group, randomized controlled trial, we examined the effect of 2 years of supervised high-intensity exercise training on LV stiffness. METHODS: Sixty-one (48% male) healthy, sedentary, middle-aged participants (53±5 years) were randomly assigned to either 2 years of exercise training (n=34) or attention control (control; n=27). Right heart catheterization and 3-dimensional echocardiography were performed with preload manipulations to define LV end-diastolic pressure-volume relationships and Frank-Starling curves. LV stiffness was calculated by curve fit of the diastolic pressure-volume curve. Maximal oxygen uptake (Vo2max) was measured to quantify changes in fitness. RESULTS: Fifty-three participants completed the study. Adherence to prescribed exercise sessions was 88±11%. Vo2max increased by 18% (exercise training: pre 29.0±4.8 to post 34.4±6.4; control: pre 29.5±5.3 to post 28.7±5.4, group×time P<0.001) and LV stiffness was reduced (right/downward shift in the end-diastolic pressure-volume relationships; preexercise training stiffness constant 0.072±0.037 to postexercise training 0.051±0.0268, P=0.0018), whereas there was no change in controls (group×time P<0.001; pre stiffness constant 0.0635±0.026 to post 0.062±0.031, P=0.83). Exercise increased LV end-diastolic volume (group×time P<0.001), whereas pulmonary capillary wedge pressure was unchanged, providing greater stroke volume for any given filling pressure (loading×group×time P=0.007). CONCLUSIONS: In previously sedentary healthy middle-aged adults, 2 years of exercise training improved maximal oxygen uptake and decreased cardiac stiffness. Regular exercise training may provide protection against the future risk of heart failure with a preserved ejection fraction by preventing the increase in cardiac stiffness attributable to sedentary aging. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02039154.

Implantation of a left ventricular assist device to provide long-term support for end-stage Duchenne muscular dystrophy-associated cardiomyopathy.

A young man with Duchenne muscular dystrophy presented to the UT Southwestern Neuromuscular Cardiomyopathy Clinic with advanced heart failure. Despite maximal medical therapy, his cardiac function continued to decline requiring initiation of inotrope therapy. Given the patient's clinical deterioration, a left ventricular assist device (LVAD) was implanted as destination therapy after undergoing a multidisciplinary assessment. The patient tolerated the surgical implantation of the LVAD without any significant complications, and he has had a relatively unremarkable course 38 months post-LVAD implantation. A critical factor contributing to the long-term success of this patient was the decision to select an LVAD that would not disrupt the diaphragm and thus preserve the respiratory muscle strength. This case demonstrates that permanent mechanical LVADs should be considered for appropriately selected Duchenne muscular dystrophy patients with medically refractory end-stage cardiomyopathy.