Cardiology

Seliem, A. and Hall, S.A. (2020). “The New Era of Cardiogenic Shock: Progress in Mechanical Circulatory Support.” Curr Heart Fail Rep 2020 Sep 16. [Epub ahead of print.].

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PURPOSE OF REVIEW: In recent decades, multiple left and right ventricular assist devices (VAD) have been developed, and the utilization of these devices has grown exponentially. We discuss the most common temporary mechanical circulatory support (tMCS) devices used for patients in cardiogenic shock, including the intra-aortic balloon pump (IABP), transvalvular axial flow support systems (Impella®), the Tandem™ collection, and extracorporeal membrane oxygenation (ECMO). RECENT FINDINGS: In 2018 the United Network for Organ Sharing (UNOS) introduced new listing criteria for candidates awaiting heart transplantation in the USA. Analysis of the first 1300 transplants under these new listing criteria has shown that higher-risk patients are now undergoing transplantation. As technology has advanced, becoming more sophisticated and miniaturized, a new era has emerged with more rapidly deployable tMCS devices. For some patients presenting in cardiogenic shock, support with these tMCS devices can be a bridge to a more durable option. For others, their only option may be support with the hope of native cardiac recovery. Understanding the pros and cons of each device can lead to most appropriate utilization for the ultimate intended goal.

Frost, P.A., Chen, S., Rodriguez-Ayala, E., Laviada-Molina, H.A., Vaquera, Z., Gaytan-Saucedo, J.F., Li, W.H., Haack, K., Grayburn, P.A., Sayers, K., Cole, S.A. and Bastarrachea, R.A. (2020). “Research methodology for in vivo measurements of resting energy expenditure, daily body temperature, metabolic heat and non-viral tissue-specific gene therapy in baboons.” Res Vet Sci Sep 20;133:136-145. [Epub ahead of print.].

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A large number of studies have shown that the baboon is one of the most commonly used non-human primate (NHP) research model for the study of immunometabolic complex traits such as type 2 diabetes (T2D), insulin resistance (IR), adipose tissue dysfunction (ATD), dyslipidemia, obesity (OB) and cardiovascular disease (CVD). This paper reports on innovative technologies and advanced research strategies for energetics and translational medicine with this NHP model. This includes the following: measuring resting energy expenditure (REE) with the mobile indirect calorimeter Breezing®; monitoring daily body temperature using subcutaneously implanted data loggers; quantifying metabolic heat with veterinary infrared thermography (IRT) imaging, and non-viral non-invasive, tissue-specific ultrasound-targeted microbubble destruction (UTMD) gene-based therapy. These methods are of broad utility; for example, they may facilitate the engineering of ectopic overexpression of brown adipose tissue (BAT) mUCP-1 via UTMD-gene therapy into baboon SKM to achieve weight loss, hypophagia and immunometabolic improvement. These methods will be valuable to basic and translational research, and human clinical trials, in the areas of metabolism, cardiovascular health, and immunometabolic and infectious diseases.

Sannino, A., Hahn, R.T., Leipsic, J., Mack, M.J. and Grayburn, P.A. (2020). “Meta-analysis of Incidence, Predictors and Consequences of Clinical and Subclinical Bioprosthetic Leaflet Thrombosis After Transcatheter Aortic Valve Implantation.” Am J Cardiol 132: 106-113.

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Leaflet thrombosis (LT) has been claimed as a potential cause of hemodynamic dysfunction or bioprosthetic valve degeneration of transcatheter heart valves. Sparse and contrasting evidence exists, however, regarding LT occurrence, prevention and treatment. MEDLINE, ISI Web of Science and SCOPUS databases were searched for studies published up to January 2020. Only studies reporting data on incidence and outcomes associated to the presence/absence of clinical or subclinical LT, detected or confirmed with a multidetector computed tomography exam were included. The study was designed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) requirements. Two reviewers independently screened articles for fulfillment of inclusion criteria. Data were pooled using a random-effect model. The primary end point was the incidence of LT. Secondary outcomes included: stroke and transient ischemic attacks and mean transvalvular gradients at different time-points in patients with and without LT. Of the initial 200 studies, 22 were finally included with a total of 11,567 patients. LT overall incidence was 8% (95% Confidence Interval [CI]: 5% to 13%, I(2) = 96.4%). LT incidence in patients receiving only antiplatelets was 13% (95% CI: 7% to 23%, p <0.0001); patients discharged on oral anticoagulants had a reported incidence of 4% (95% CI: 2% to 8%, p <0.0001). Patients with LT, either clinical or subclinical, were not at increased risk of stroke (OR 1.06, 95% CI: 0.75 to 1.50, p = 0.730, I(2) = 0.0%) or transient ischemic attacks (Odds Ratio 1.01, 95% CI: 0.40 to 2.57, p = 0.989, I(2) = 0.0%). LT was associated with higher mean transvalvular gradients compared with patients without LT at 30 days post-transcatheter implantation, but not at discharge or at 1 year. LT is a relatively common event that, even when clinically manifest, is not associated with an increased risk of cerebrovascular events. Although patients on anticoagulants appear to be at lower risk of LT, the available evidence does not allow formulation of recommendations for prophylactical anticoagulation nor routine computed tomography after transcatheter aortic valve replacement.

Carey, S.A., Afzal, A., Jamil, A., Williams, S. and Gottlieb, R.L. (2020). “Outpatient COVID-19 surveillance testing in orthotopic heart transplant recipients.” Clin Transplant Sep 25;e14105. [Epub ahead of print.]. e14105.

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COVID-19 case fatality rate in the United States is currently reported at 4.8% based on the confirmed cases of COVID-19. However, there are conflicting reports of estimated deaths in the post-cardiac transplantation patient population associated with COVID-19. METHODS: Observational, retrospective analysis of a large cohort of post Orthotopic Heart Transplantation (OHT) patients in a high volume heart transplantation program in Dallas, Texas underwent outpatient COVID-19 screening and testing for both SARS-CoV-2 nasopharyngeal RT-PCR and anti-SARS-CoV2 IgG serology as a result of a clinic protocol to facilitate re-opening of face-to-face outpatient clinical visits. RESULTS: The full outpatient cohort tested at time of their clinic visit tested negative for COVID-19 by nasopharyngeal RT-PCR. Only 2 patients tested seropositive for anti-SARS-COV2 IgG. Five positive inpatient cases were also identified and all, but one recovered. CONCLUSION: A COVID-19 surveillance protocol can be easily instituted in this high-risk population and facilitate safe transplant clinic operation. As the cases and prevalence increase across the United States, further strategies will need to be developed to determine the best course of action to help manage this select population while minimizing their exposure to the ongoing pandemic.

Gong, T. and Hall, S. (2020). “Considerations and experience driving expansion of combined heart-liver transplantation.” Curr Opin Organ Transplant 25(5): 496-500

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PURPOSE OF REVIEW: Heart transplantation concomitant with a liver transplant may be warranted when end-stage heart failure results in irreversible liver failure. Previously reported outcomes have been excellent yet the specific immunoprotective role of the liver allograft is not known. We review the current literature about the immunologic benefit for combined heart and liver transplantation (CHLT). RECENT FINDINGS: The total number of combined heart and liver transplants continues to increase and accounts for approximately 25 cases per year. Familial amyloid polyneuropathy with cardiac cirrhosis is the most common indication for CHLT while adult congenital heart disease (CHD) with associated cirrhosis is increasing in frequency. The majority of recent registry data suggest a statistically equivalent to modestly improved survival advantage for CHLT compared with isolated heart transplantation. Direct mechanisms accounting for this survival advantage are not proven, but combined heart and liver transplants experience lower rates of acute cardiac rejection and cardiac allograft vasculopathy (CAV). SUMMARY: Combined heart and liver transplants remain a small percentage of the total heart transplants worldwide, but the majority of recent literature confirms the safety and viability of this option for patients with end-stage heart and liver disease. Equivalent to modestly improved survival outcomes, lower rates of acute cardiac rejection and CAV warrant further investigation into the liver allograft’s immunoprotective effect on the transplanted heart. The key mechanisms of tolerogenicity have important implications for surgical technique and immunosuppression requirements. Future directions include development of criteria for heart-liver transplant candidacy and identification of equitable allocation protocols.