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Background: Expert opinion and professional society statements have called for multi-tier care systems for the management of cardiogenic shock (CS). However, little is known about how to pragmatically define centers with different levels of care (LOC) for CS., Methods: Eleven of 23 hospitals within our healthcare system sharing a common electronic health record were classified as different LOC according to their highest mechanical circulatory support (MCS) capabilities: Level 1 (L-1)-durable left ventricular assist device, Level 1A (L-1A)-extracorporeal membrane oxygenation, Level 2 (L-2)-intra-aortic balloon pump and percutaneous ventricular assist device; and Level 3 (L-3)-no MCS. All adult patients treated for CS (International Classification of Diseases, ICD-10 code R57.0) between 2016 and 2022 were included. Etiologies of CS were identified using associated diagnostic codes. Management strategies and outcomes across LOC were compared., Results: Higher LOC centers had higher volumes: L-1 ( n  = 1): 2,831 patients, L-1A ( n  = 4): 3,452, L-2 ( n  = 1): 340, and L-3 ( n  = 5): 780. Emergency room admissions were more common in lower LOC (96% at L-3 vs. 46% L-1; p  < 0.001), while hospital transfers were predominant at higher LOC (40% at L-1 vs. 2.7% at L-3; p  < 0.001). Men comprised 61% of the cohort. Patients were younger in the higher LOC [69 (60-78) years at L-1 vs. 77 (67-85) years at L-3; p  < 0.001]. Patients with acute myocardial infarction (AMI)-CS and acute heart failure (AHF)-CS were concentrated in higher LOC centers while other etiologies of CS were more common in L-2 and L-3 ( p  < 0.001). Cardiac arrest on admission was more prevalent in lower LOC centers (L-1: 2.8% vs. L-3: 12.1%; p  < 0.001). Patients with AMI-CS received more percutaneous coronary intervention in lower LOC (51% L-2 vs. 29% L-1; p  < 0.01) but more coronary arterial bypass graft surgery at higher LOC (L-1: 42% vs. L-1A: 23%; p  < 0.001). MCS use was consistent across levels for AMI-CS but was more frequent in higher LOC for AHF-CS patients (L-1: 28% vs. L-2: 10%; p  < 0.001). Despite increasing in-hospital mortality with decreasing LOC, no significant difference was seen after multivariable adjustment., Conclusion: This is the first report describing a pragmatic classification of LOC for CS which, based on MCS capabilities, can discriminate between centers with distinct demographics, practice patterns, and outcomes. This classification may serve as the basis for future research and the creation of CS systems of care., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Alvarez Villela, Fu, Roslin, Smoller, Asemota, Miklin, Kodra, Vullaganti, Roswell, Rangasamy, Saikus, Kon, Pierce, Husk, Stevens and Maybaum.)

Objectives: To compare the outcomes of hybrid coronary revascularization (HCR) with traditional coronary artery bypass grafting (CABG) in multivessel coronary artery disease (MVCAD)., Background: HCR has emerged as an alternative to CABG in patients with MVCAD. Through minimally invasive surgical techniques, HCR carries the potential for faster recovery postoperatively, fewer complications, and lower utilization of resources., Methods: Systematic search of electronic databases was conducted up to December 2021 and studies comparing HCR with CABG in the treatment of MVCAD were included in this meta-analysis. Primary outcomes of interest were incidence of 5-year mortality and major adverse cardiac and cerebral event (MACCE)., Results: Fourteen studies (12 observational studies and 2 randomized controlled trials) comprising 4226 patients were included. The rates of 5-year mortality (odds ratios [OR]: 1.55; 95% confidence interval [CI]: 0.92-2.62; I 2  = 83.0%) and long-term MACCE (OR: 0.97; 95% CI: 0.47-2.01; I 2  = 74.7%) were comparable between HCR and CABG groups. HCR was associated with a significantly lower likelihood of perioperative blood transfusion (OR: 0.36; 95% CI: 0.25-0.51; I 2  = 55.9%), shorter mean hospital stay (weighted mean difference: -2.04; 95% CI: -2.60 to -1.47; I 2  = 54%), and risk of postoperative acute kidney injury (OR: 0.45; 95% CI: 0.23-0.88; p = 0.02). CABG demonstrated a lower likelihood of requiring long-term repeat revascularization (OR: 1.51; 95% CI: 1.03-2.20; I 2  = 18%) over a follow-up duration of 29.14 ± 21.75 months., Conclusion: This meta-analysis suggests that HCR is feasible and safe for the treatment of MVCAD. However, benefits of HCR should be carefully weighed against the increased long-term risk of repeat-revascularization when selecting patients, and further studies evaluating differences in long-term mortality between HCR and CABG are required., (© 2022 Wiley Periodicals LLC.)

Competing Interests: Disclosure: The authors have no conflicts of interest to report.

Hyperbaric Oxygen (HBO 2 ) has been proposed as a pre-conditioning method to enhance exercise performance. Most prior studies testing this effect have been limited by inadequate methodologies. Its potential efficacy and mechanism of action remain unknown. We hypothesized that HBO 2 could enhance aerobic capacity by inducing mitochondrial biogenesis via redox signaling in skeletal muscle. HBO 2 was administered in combination with high-intensity interval training (HIIT), a potent redox stimulus known to induce mitochondrial biogenesis. Aerobic capacity was tested during acute hypobaric hypoxia seeking to shift the limiting site of whole body V̇O2 from convection to diffusion, more closely isolating any effect of improved oxidative capacity. Healthy volunteers were screened with sea-level (SL) V̇O 2 peak testing. Seventeen subjects were enrolled (10 men, 7 women, ages 26.5±1.3 years, BMI 24.6±0.6 kg m -2 , V̇O 2 peak SL = 43.4±2.1). Each completed 6 HIIT sessions over 2 weeks randomized to breathing normobaric air, "HIIT+Air" (PiO 2 = 0.21 ATM) or HBO 2 (PiO 2 = 1.4 ATM) during training, "HIIT+HBO 2 " group. Training workloads were individualized based on V̇O 2 peak SL test. Vastus Lateralis (VL) muscle biopsies were performed before and after HIIT in both groups. Baseline and post-training V̇O 2 peak tests were conducted in a hypobaric chamber at PiO2 = 0.12 ATM. HIIT significantly increased V̇O 2 peak in both groups: HIIT+HBO 2 31.4±1.5 to 35.2±1.2 ml kg -1 ·min -1 and HIIT+Air 29.0±3.1 to 33.2±2.5 ml kg -1 ·min -1 ( p = 0.005) without an additional effect of HBO 2 ( p = 0.9 for interaction of HIIT x HBO 2 ). Subjects randomized to HIIT+HBO 2 displayed higher skeletal muscle mRNA levels of PPARGC1A , a regulator of mitochondrial biogenesis, and HK2 and SLC2A4 , regulators of glucose utilization and storage. All other tested markers of mitochondrial biogenesis showed no additional effect of HBO 2 to HIIT. When combined with HIIT, short-term modest HBO 2 (1.4 ATA) has does not increase whole-body V̇O 2 peak during acute hypobaric hypoxia. (ClinicalTrials.gov Identifier: NCT02356900; https://clinicaltrials.gov/ct2/show/NCT02356900)., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Alvarez Villela, Dunworth, Kraft, Harlan, Natoli, Suliman and Moon.)

Background: The use of the HeartMate 3 (HM3) left ventricular assist device (LVAD) is expanding. Despite being associated with lower rates of adverse events and increased survival, outflow graft obstruction (OGO) has been reported in patients with HM3. The incidence and best management of this serious complication remain unclear., Methods: We describe six cases of HM3 OGO occurring in five patients in our institutional HM3 cohort. Four cases underwent computed tomography angiography and in two percutaneous angiography was directly performed to confirm the diagnosis. In four cases, percutaneous repair of the OG was performed using common interventional cardiology (IC) techniques., Results: Our institutional incidence of OGO was 7% (event rate of 0.05 per patient year); much higher than the previously reported incidence of 1.6%. All cases occurred in the bend relief covered segment. Only two patients had apparent OG twisting, and in two, OGO occurred despite placement of an anti-twist clip at the time of implant. External compression seems to play a role in most cases. Balloon "graftoplasty" and stent deployment via the femoral artery alleviated the obstruction and normalized LVAD flow in all patients who underwent percutaneous repair. The use of self-expanding stents allowed for downsizing of the procedural access site to 10 Fr. No serious procedure-related complications occurred., Conclusion: OGO is common in HM3 patients, external compression due to biomaterial accumulated surrounding the OG is a common etiology. Percutaneous repair using standard IC techniques is safe and feasible in cases of compression with or without partial twisting., (© 2021 Wiley Periodicals LLC.)

Outcomes for cardiogenic shock (CS) patients remain relatively poor despite significant advancements in primary percutaneous coronary interventions (PCI) and temporary circulatory support (TCS) technologies. Mortality from CS shows great disparities that seem to reflect large variations in access to care and physician practice patterns. Recent reports of different models to standardize care in CS have shown considerable potential at improving outcomes. The creation of regional, integrated, 3-tiered systems, would facilitate standardized interventions and equitable access to care. Multidisciplinary CS teams at Level I centers would direct care in a hub-and-spoke model through jointly developed protocols and real-time shared decision making. Levels II and III centers would provide early access to life-saving therapies and safe transfer to designated hub centers. In regions with large geographical distances, the implementation of telemedicine-cardiac intensive care unit (CICU) care can be an important resource for the creation of effective systems of care., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Alvarez Villela, Clark, William, Sims and Jorde.)

Aims: Patients with left ventricular assist device (LVAD) suffer from persistent exercise limitation despite improvement of their heart failure syndrome. Exercise training (ET) programmes to improve aerobic capacity have shown modest efficacy. High-intensity interval training (HIIT), as an alternative to moderate continuous training, has not been systematically tested in this population. We examine the feasibility of a short, personalized HIIT programme in patients with LVAD and describe its effects on aerobic capacity and left ventricular remodelling., Methods and Results: Patients on durable LVAD support were prospectively enrolled in a 15-session, 5 week HIIT programme. Turndown echocardiogram, Kansas City Cardiomyopathy Questionnaire, and cardiopulmonary exercise test were performed before and after HIIT. Training workloads for each subject were based on pretraining peak cardiopulmonary exercise test work rate (W). Percentage of prescribed training workload completed and adverse events were recorded for each subject. Fifteen subjects were enrolled [10 men, age = 51 (29-71) years, HeartMate II = 12, HeartMate 3 = 3, and time on LVAD = 18 (3-64) months]. Twelve completed post-training testing. HIIT was well tolerated, and 90% (inter-quartile range: 78, 99%) of the prescribed workload (W) was completed with no major adverse events. Improvements were seen in aV̇O 2 at ventilatory threshold [7.1 (6.5, 9.1) to 8.5 (7.7, 9.3) mL/kg/min, P = 0.04], work rate at ventilatory threshold [44 (14, 54) to 55 (21, 66) W, P = 0.05], and left ventricular end-diastolic volume [168 (144, 216) to 159 (124, 212) mL, n = 7, P = 0.02]. HIIT had no effect on maximal oxygen consumption (V̇O 2peak ) or Kansas City Cardiomyopathy Questionnaire score., Conclusions: Cardiopulmonary exercise test-guided HIIT is feasible and can improve submaximal aerobic capacity in stable patients with chronic LVAD support. Further studies are needed on its effects on the myocardium and its potential role in cardiac rehabilitation programmes., (©2020 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.)

In Spring 2020, the United States epicenter of COVID-19 was New York City, in which the borough of the Bronx was particularly affected. This Fall, there has been a resurgence of COVID-19 in Europe and the Midwestern United States. We describe our experience transforming our cardiac catheterization laboratories to accommodate an influx of COVID-19 patients so as to provide other hospitals with a potential blueprint. We transformed our pre/postprocedural patient care areas into COVID-19 intensive care and step-down units and maintained emergent invasive care for ST-segment elevation myocardial infarction using existing space and personnel.

Scuba diving is a critical activity for commercial industry, military activities, research, and public safety, as well as a passion for many recreational divers. Physicians are expected to provide return-to-diving recommendations after SARS-CoV-2 (COVID-19) infection based upon the best available evidence, often drawn from experience with other, similar diseases. Scuba diving presents unique physiologic challenges to the body secondary to immersion, increased pressure and increased work of breathing. The long-term sequelae of COVID-19 are still unknown, but if they are proven to be similar to other coronaviruses (such as Middle East respiratory syndrome or SARS-CoV-1) they may result in long-term pulmonary and cardiac sequelae that impact divers' ability to safely return to scuba diving. This review considers available literature and the pathophysiology of COVID-19 as it relates to diving fitness, including current recommendations for similar illnesses, and proposes guidelines for evaluation of divers after COVID-19. The guidelines are based upon best available evidence about COVID-19, as well as past experience with determination of diving fitness. It is likely that all divers who have contracted COVID-19 will require a medical evaluation prior to return to diving with emphasis upon pulmonary and cardiac function as well as exercise capacity., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

Objective: To describe the structural sequelae of carbon monoxide (CO) poisoning on the heart assessed using stress cardiac MRI (CMR). CO poisoning is common. While acute cardiac injury is frequent among survivors, the mid- and long-term effects of CO on the myocardium are unclear., Methods: CMR studies performed between the years 2005 and 2014 for a primary diagnosis of CO poisoning at a tertiary care center were reviewed by an experienced cardiologist. Variables of interest were compared between patients with normal and abnormal studies to identify factors associated with cardiac dysfunction., Results: Eighty-eight patients underwent stress CMR, age 34 years (range 11-70); 49% were male, 74 had acute poisoning and 14 had chronic poisoning (CO exposure for longer than 24 hours). Time from CO poisoning to imaging was 24 months (1 day-120 months). Patients were stratified into four categories, which included those with acute poisoning imaged: ≤12 months; 12-60 months; >60 months from the event; and those with chronic poisoning. Overall, 26 studies (30%) were abnormal. The most common findings were: left ventricular systolic dysfunction in 14 patients, right ventricular systolic dysfunction in nine, and LV dilatation in six. Abnormalities were mild in most cases and were equally prevalent in all four patient categories. Dyspnea at the time of follow-up was more frequent among those with abnormal studies., Conclusion: Mild alterations in ventricular structure and function are frequent in survivors of CO poisoning. Myocardial scarring is rare, suggesting that acute hypoxic injury may not fully explain these abnormalities., Competing Interests: The authors of this paper declare no conflicts of interest exist with this submission., (Copyright© Undersea and Hyperbaric Medical Society.)