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Background: Cardiac rehabilitation (CR) is essential to secondary cardiovascular disease prevention and management of cardiac patients. Despite its proven benefits, CR remains underutilized with enrollment and completion rates ranging from 10-30% in the US. Yet, there is a scarcity of nationally representative data among diverse populations on socioeconomic differences in barriers and beliefs of CR participation and delivery mode preferences. Hypothesis: The perceptions (barriers, beliefs), CR delivery mode preferences, and CR utilization (prior enrollment) varies by socioeconomic status (SES) among CR-eligible individuals. Methods: We conducted an anonymous national electronic survey from March 2023 to January 2024 of individuals self-reporting a prior CR-eligible diagnosis. The 22-item CR Barriers Scale assessed perceived barriers to CR enrollment and participation using a 5-point Likert scale (strongly disagree to strongly agree). A 13-item, validated questionnaire assessed 4 subscales pertaining to patients’ beliefs about CR, each rated on a 5-point Likert scale (strongly disagree to strongly agree): perceived necessity, concerns about exercise, practical barriers and perceived suitability. CR delivery mode preferences were ascertained (eg, virtual, at-home, etc.). Mean barriers and belief scores as well as delivery mode preferences were stratified by SES. Low SES was defined as ≤ high school education, Medicaid insurance, or uninsured. High SES was defined as > high school education and non-Medicaid health insurance. Responses were analyzed using descriptive statistics with R software. Results: A total of 466 participants completed the survey (38.1% women, 30.6% minoritized racial/ethnic group, 29.6% low SES, 95% response rate) ( Table 1 ). The majority indicated prior enrollment in CR (81.5%) with no difference by SES. CR barrier scores did not differ significantly by SES (p=0.331) ( Table 2 ). Beliefs about CR perceived necessity and perceived suitability differed by SES (p<0.001 and p=0.025), but beliefs regarding concerns about exercise and practical barriers did not. The low SES group reported a higher preference for completely at-home CR compared to the high SES group (33.6% vs 7.4%, p<0.001). Conclusion: Our findings suggest that CR beliefs varied by SES while utilization did not. For CR-eligible patients experiencing socioeconomic disadvantage, at-home CR may be a preferred alternative to center-based CR to increase CR participation and adherence.

Background: Despite expert opinion recommending patient-tailored cardiac rehabilitation (CR) after acute aortic dissection, both patient participation in CR and the associated risk factor modification after CR following aortic dissection repair are poorly understood. Objectives: To describe the characteristics of patients referred to CR, as well as the enrollment rate and outcomes of those referred to CR following thoracic aortic dissection. Methods: We reviewed electronic health records of adults (≥18) discharged alive following thoracic aortic dissection surgery across the Mayo Clinic Enterprise (01/01/2020-11/15/2022) with follow-up to 05/15/2024 (IRB #24-001141). Data are presented using summary statistics. Results: During the study period, 85 patients were included (median [IQR] age: 65 [50-75] years; 40% female; Table 1 ). Across 84% (N=71) who were referred to CR at discharge, 55% (N=39) enrolled. In those patients referred versus not referred to CR, the prevalence of type A dissection (75% vs. 43%), end-organ involvement (27% vs. 0%), and underlying CAD (54% vs. 21%) were greater while current tobacco use (9% vs. 29%) was lower. Of those enrolled at Mayo Clinic (N=16), CR was started 35 (28-65) days following surgery. These patients completed 21 (13-30) CR sessions at an exercise intensity of 59% (50-65%) maximum predicted heart rate. CR was discontinued in 44% (N=7) due to non-cardiac reasons ( Table 2 ). Of the 9 patients who completed CR, general health status (Dartmouth index: 19 [17-21] vs. 26 [22-34]), depressive symptoms (PHQ-9: 1 [0-1] vs. 4 [1-4]), and exercise capacity (6MWT: 214 [196-244] vs. 384 [305-597] meters) improved ( Table 2 ). There were no reported complications or deaths, with stable aortic sizes reported at 18 months. Conclusions: CR improves functional capacity and well-being without complications in patients after thoracic aortic dissection surgery. Further investigation is needed to better assess CR efficacy and usage in this population.

Exercise-induced respiratory muscle fatigue contributes to limiting exercise tolerance. Accordingly, better understanding the exercise conditions under which respiratory muscle fatigue occurs is warranted. Although heavy-intensity as well as short- and long-duration severe-intensity exercise performed to intolerance elicit diaphragm and expiratory muscle fatigue, we find, for the first time, that the relationship between exercise intensity, exercise duration, and the magnitude of exercise-induced fatigue is different for the diaphragm compared with the expiratory muscles.

Cardiogenic pulmonary edema is a life-threatening complication in patients with heart failure (HF) resulting from increased alveolar Cl- secretion and inhibition of alveolar epithelial Na+ channels (ENaC). Not all HF patients develop pulmonary edema, despite similar clinical characteristics, suggesting a genetic component to edema formation in response to cardiac failure. The ENaC are crucial for alveolar fluid clearance, with the alpha subunit demonstrating particular importance. We have previously found that genetic variation of the alpha subunit (SCNN1A) of ENaC, an alanine (A) to threonine (T) substitution, influences ion regulation during exercise and in response to albuterol. In the present study, we sought to determine the influence of the threonine variant (T663; AT/TT group) on lung fluid regulation in response to normobaric hypoxia, an environmental condition known to increase pulmonary capillary hydrostatic stress in healthy humans. Lung ion and fluid changes were assessed using exhaled Na+ (ENa+) and the lung diffusing capacity for carbon monoxide and nitric oxide (DLCO and DLNO, respectively) to determine alveolar-capillary membrane conductance (DM). 19 healthy subjects (n=8 vs. 11, %female=50 vs. 62%, age=27±1 vs. 28±2yrs., ht=171±3 vs. 173±2cm, wt=69±6 vs.72±3kg , BMI=23±1 vs.24±1kg/m2 , for AA and AT/TT, respectively) completed two overnight visits in a hypoxic tent simulating just over 5,400m. The visits were randomized to inhaled placebo (P) or inhaled amiloride (Aml, 1.5mg in 5ml normal saline, used to inhibit ENaC activity) with ENa+, DLCO, and DM assessed at baseline and following 12 hours of hypoxic exposure. There was an effect of genotype on the ENa+ response to hypoxia with placebo that was abolished with amiloride, but no effect of genotype on the diffusing capacity of the lung (Table). These results suggest that genetic variation of SCNN1A may influence ion regulation in the lung under conditions of elevated hydrostatic stress.

ABSTRACT Introduction Endurance exercise at altitude can increase cardiac output and pulmonary vascular pressure to levels that may exceed the stress tolerability of the alveolar–capillary unit. This study examined the effect of ultramarathon trail racing at different altitudes (ranging from <1000 m to between 1500 and 2700 m) on alveolar–capillary recruitment and lung diffusion. Methods Cardiac and lung function were examined before and after an ultramarathon in 67 runners (age: 41 ± 9 yr, body mass index: 23 ± 2 kg·m −2 , 10 females), and following 12–24 h of recovery in a subset ( n = 27). Cardiac biomarkers (cTnI and BNP) were assessed from whole blood, whereas lung fluid accumulation (comet tails), stroke volume (SV), and cardiac output ( Q ) were quantified via echocardiography. Lung diffusing capacity for carbon monoxide (DLco) and its components, alveolar membrane conductance (Dm) and capillary blood volume (Vc), were determined via a single-breath method at rest and during three stages of submaximal semirecumbent cycling (20, 30, and 40 W). Results Average race time was 25 ± 12 h. From pre- to post-race, there was an increase in cardiac biomarkers (cTnI: 0.04 ± 0.02 vs 0.13 ± 0.03 ng·mL −1 , BNP: 20 ± 2 vs 112 ± 21 pg·mL −1 ; P < 0.01) and lung comet tails (2 ± 1 vs 7 ± 6, P < 0.01), a decrease in resting and exercise SV (76 ± 2 vs 69 ± 2 mL, 40 W: 93 ± 2 vs 88 ± 2 mL; P < 0.01), and an elevation in Q at rest (4.1 ± 0.1 vs 4.6 ± 0.2 L·min −1 , P < 0.01; 40 W: 7.3 ± 0.2 vs 7.4 ± 0.3 L·min −1 , P = 0.899). Resting DLco and Vc decreased after the race ( P < 0.01), whereas Dm was unchanged ( P = 0.465); however, during the three stages of exercise, DLco, Vc, and Dm were all reduced from pre- to post-race (40 W: 36.3 ± 0.9 vs 33.0 ± 0.8 mL·min −1 ·mm Hg −1 , 83 ± 3 vs 73 ± 2 mL, 186 ± 6 vs 170 ± 7 mL·min −1 ·mm Hg −1 , respectively; P < 0.01). When corrected for alveolar volume and Q , DLco decreased from pre- to post-race ( P < 0.01), and changes in DLco were similar for all ultramarathon events ( P > 0.05). Conclusions Competing in an ultramarathon leads to a transient increase in cardiac injury biomarkers, mild lung-fluid accumulation, and impairments in lung diffusion. Reductions in DLco are predominantly caused by a reduced Vc and possible pulmonary capillary de-recruitment at rest. However, impairments in alveolar–capillary recruitment and Dm both contribute to a fall in exertional DLco following an ultramarathon. Perturbations in lung diffusion were evident across a range of event distances and varying environmental exposures.

Background Innovative restructuring of cardiac rehabilitation (CR) delivery remains critical to reduce barriers and improve access to diverse populations. Destination Cardiac Rehab is a novel virtual world technology‐based CR program delivered through the virtual world platform, Second Life, which previously demonstrated high acceptability as an extension of traditional center‐based CR. This study aims to evaluate efficacy and adherence of the virtual world–based CR program compared with center‐based CR within a community‐informed, implementation science framework. Methods Using a noninferiority, hybrid type 1 effectiveness‐implementation, randomized controlled trial, 150 patients with an eligible cardiovascular event will be recruited from 6 geographically diverse CR centers across the United States. Participants will be randomized 1:1 to either the 12‐week Destination Cardiac Rehab or the center‐based CR control groups. The primary efficacy outcome is a composite cardiovascular health score based on the American Heart Association Life's Essential 8 at 3 and 6 months. Adherence outcomes include CR session attendance and participation in exercise sessions. A diverse patient/caregiver/stakeholder advisory board was assembled to guide recruitment, implementation, and dissemination plans and to contextualize study findings. The institutional review board–approved randomized controlled trial will enroll and randomize patients to the intervention (or control group) in 3 consecutive waves/year over 3 years. The results will be published at data collection and analyses completion. Conclusions The Destination Cardiac Rehab randomized controlled trial tests an innovative and potentially scalable model to enhance CR participation and advance health equity. Our findings will inform the use of effective virtual CR programs to expand equitable access to diverse patient populations. Registration URL: https://www.clinicaltrials.gov ; Unique identifier: NCT05897710.

There is accumulating evidence that reduced exercise capacity is, or can be, an outcome following COVID-19. However, evidence to date relies upon cross-sectional approaches that either do not consider patients with concomitant cardiorespiratory disease or account for pre-infection exercise capacity data. Accounting for V̇o2peak before COVID-19 and including a group of control patients, we find limited evidence for reduced exercise capacity as a sequela of SARS-CoV-2 infection in patients with concomitant cardiorespiratory disease.