Bonikowske, Amanda R.

Background Cardiac rehabilitation (CR) improves peak oxygen uptake (VO 2 peak) and body composition in patients with cardiovascular disease. However, improvement in VO 2 peak is not observed in all patients following a CR program, and whether VO 2 peak non-responders also demonstrate limited changes in body composition remains unclear. This study aimed to examine the association between changes in VO 2 peak and body composition in patients undergoing a CR program. Methods Retrospective analysis of patients who completed CR between 2015 and 2022 at Mayo Clinic. The study included 143 patients who completed cardiopulmonary exercise testing and dual-energy X-ray absorptiometry pre- and post-CR. Patients were grouped by the change in relative VO 2 peak response to CR (responders= Δ>0 vs non-responders=Δ ≤0 mL/kg/min). Two-way repeated ANOVA was used to compare groups, and regression models were used to examine the associations between baseline body composition and changes in body composition with VO 2 peak change. Results Among the cohort, 26% were classified as non-responders based on relative VO 2 peak measurements. Both groups exhibited a significant improvement in most body composition variables including body fat mass, body fat percentage, body lean percentage, and fat mass index (all p<0.001), with no differences in the percentage of change in body composition variables between groups (p>0.05). Regression models demonstrated that neither baseline body composition nor changes in body composition were significantly associated with changes in VO 2 peak. Conclusion Our data suggest that baseline and change in body composition were not significantly associated with changes in VO 2 peak in patients undergoing the CR program.

Background Cardiac rehabilitation (CR) leads to increased exercise capacity (VO 2 peak) and risk reduction of major adverse cardiovascular events (MACEs). Women exhibit blunted VO 2 peak improvements following CR. The purpose was to examine sex differences in the clinical predictors of VO 2 peak improvement and odds of MACEs following CR. Methods From 1999 to 2017, all consecutive patients undergoing cardiopulmonary exercise testing before and after CR were included. Sex differences in peak exercise metrics in response to CR were compared. Multiple logistic regression models were fit to assess clinical predictors of VO 2 peak improvement (defined as >0% from pre‐CR) and MACEs following CR for men and women. Results A total of 513 men and 158 women were included. Men had greater increases in VO 2 peak than women following CR ( P =0.001). For men, independent predictors of VO 2 peak improvement following CR included higher CR session attendance (odds ratio [OR], 1.04 [95% CI, 1.02–1.06]), peripheral artery disease (OR, 0.47 [95% CI, 0.25–0.86]), and pre‐CR VO 2 peak (OR, 0.98 [95% CI, 0.97–0.99]) (all, P <0.02). Independent predictors of lower odds of MACEs following CR in men included higher number of CR sessions (OR, 0.97 [95% CI, 0.95–0.99]), pre‐CR VO 2 peak (OR, 0.98 [95% CI, 0.97–0.99]), surgical CR indication (OR, 0.34 [95% CI, 0.18–0.68]), and no history of peripheral artery disease (OR, 2.94 [95% CI, 1.60–5.38]) (all, P <0.02). For women, the selected clinical characteristics were not statistically significant independent predictors of VO 2 peak improvement or odds of MACEs (except for diabetes) following CR. Conclusions These findings suggest that clinical predictors of VO 2 peak improvement and odds of MACEs following CR are sex specific.

Abstract Background The implications of poor sleep for cardiovascular disease risk are increasingly recognised. Although previous research has focused on clinical sleep disorders, emerging evidence highlights the relevance of subclinical sleep aspects for cardiovascular health. Sleep midpoint, an index of sleep timing and a proxy of circadian phase, has been shown to be associated with markers of cardiometabolic risk, including obesity, in the general population. Purpose We aimed to assess whether sleep midpoint was related to body composition measures in patients with coronary heart disease enrolled in cardiac rehabilitation (CR). Methods Study participants were recruited from the patient population referred to our CR center for acute coronary syndrome or coronary revascularisation. Shift work was exclusionary. Participants underwent sleep testing prior to entering the CR program, including completion of one week of wrist actigraphy and sleep log. Using actigraphy-derived sleep metrics, sleep midpoint was calculated as the middle time (hh:mm) between bedtime and wake up time for each individual night, and averaged across the monitoring week. Based on the median sleep midpoint of the sample, participants were categorised as having early (before 2:42) or late (after 2:42) sleep midpoint. Body composition and regional fat distribution were determined by whole-body dual-energy absorptiometry (DEXA). Between-group characteristics were compared using independent t-test, Mann-Whitney U test and Chi-square statistics as appropriate. Linear regression was used to test the association between sleep midpoint and body fat measures. Results Thirty-one participants (26 males, 64.7±12.5 years) completed both actigraphy and DEXA assessments. Demographics, lifestyle, and clinical characteristics were similar between patients with early sleep midpoint (n=15; sleep midpoint, hh:mm: 2:00, range 0:57 to 2:41) and patients with late sleep midpoint (n=16; sleep midpoint 3:18, range 2:42 to 4:17). Despite comparable body mass index between groups (p=0.21), patients with late sleep midpoint had significantly higher total body fat percentage (p=0.017), android fat percentage (p=0.015), and gynoid fat percentage (p=0.045). Late sleep midpoint remained significantly associated with adiposity measures in age- and sex-adjusted analysis (total body fat percentage, beta = 0.371, 95% CI 0.063 to 0.68; android fat percentage, beta = 0.394, 95% CI 0.078 to 0.71; gynoid fat percentage, beta = 0.301, 95% CI 0.007 to 0.596). Conclusions Late sleep midpoint was associated with excess adiposity in patients with coronary heart disease enrolled in CR. These findings support the predictive value of sleep timing for cardiometabolic risk and emphasise the importance of objective sleep assessment for secondary prevention.

Background: Sleep regularity is emerging as an independent determinant of health. Multiple studies suggest a link between increased variability in sleep duration and timing and adverse cardiovascular, metabolic, and cognitive outcomes. There is, however, a lack of data on the implications of sleep regularity for aerobic capacity and physical endurance, particularly in patients with established cardiovascular disease. This study seeks to investigate the influence of irregularity in sleep duration on functional capacity in patients with coronary artery disease (CAD) undergoing cardiac rehabilitation (CR). Methods: We recruited a sample of patients with CAD who were referred to CR at Mayo Clinic Rochester. Participants completed a 6-minute walk test (6MWT) upon enrollment into CR. 6MWT variables included distance walked (meters), predicted distance walked (percentage) and estimated metabolic equivalents (METs). 24-hour objective sleep quality and quantity were assessed over a 7-day period by wrist actigraphy. Average standard deviation (SD) of sleep duration was used to define sleep regularity, with SD >60 minutes indicating irregular sleep. Chi-square test, independent samples t-test, and linear regression were used for statistical analysis. Results: Twenty-eight participants with valid actigraphy and 6MWT were included in this analysis (eight females; mean age 67.4 ± 11.6 years; body mass index 31.1 ± 5.8 kg/m 2 ). The average total sleep time was 7.1 ± 1.2 hours, and 10 participants (35.7%) exhibited sleep duration SD >60 minutes. Demographic, clinical and sleep characteristics were comparable between the regular and irregular sleep groups. Compared to patients with regular sleep, those with irregular sleep had poorer 6MWT, with shorter distance walked (406.2 ± 81.2 meters vs 338.8 ± 80.7 meters; p = 0.045), lower % of predicted distance walked (87.1 ± 18.7% vs 69.2 ± 11.4%; p = 0.011), and lower METS (2.99 ± 0.36 vs 2.63 ± 0.38; p = 0.022). Irregular sleep remained significantly associated with performance at the 6MWT after taking into account age and sex, with patients walking 14.4 meters fewer with every 10-minute increase in sleep variability (95% CI -28.1, -0.7; p 0.041). Conclusions: Increased day-to-day fluctuation in sleep duration is associated with reduced exercise capacity in patients with CAD undergoing CR. These findings add to the mounting body of evidence linking irregular sleep patterns to heightened cardiovascular risk, and support the integration of sleep monitoring in the CR practice to enhance risk stratification and outcome prediction. Funding Source: Sleep Number Corp. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Apply It! • This electrocardiogram (ECG) primer will provide basic knowledge and standardized strategies needed to prepare and complete a resting ECG, as well as adjust electrode placement for exercise testing. • A simple, evidence-based, systematic approach to resting and exercise ECG interpretation is included. • Exercise professionals may directly apply these concepts to diverse settings, including clinics, hospitals, cardiac rehabilitation, stress testing, research, and academia.

Purpose. Spontaneous coronary artery dissection (SCAD) has emerged as an important cause of acute coronary syndrome predominantly affecting women. Although the knowledge of SCAD has expanded over the past 2 decades, limited evidence exists to guide post-event management and prevention of future adverse events. This review aims to synthesize the current understanding of SCAD and outline considerations for exercise prescription and cardiac rehabilitation (CR) in this unique population. Review Methods. A comprehensive literature review was conducted, incorporating original research articles, systematic reviews, meta-analyses, and current clinical guidelines related to SCAD and CR. Summary. Current literature demonstrates that CR is safe in this population and is associated with improvement in measures of physical and mental health. Expert consensus supports reintroduction of exercise and an individualized multidisciplinary CR framework.This review highlights current evidence and expert recommendations for the multidisciplinary outpatient management of patients with SCAD.

Purpose: Despite the 2022 American Heart Association/American College of Cardiology guidelines recommending cardiac rehabilitation (CR) after aortic dissection repair, both patient participation in CR and the associated clinical outcomes remain poorly understood. Methods: Adults (≥18 years of age) discharged alive following thoracic aortic dissection surgery across the Mayo Clinic Enterprise (January 2012 to November 2022), with follow-up until May 2024, were included (IRB #24-001141). Data were presented using summary statistics and logistic regression modeling. Results: A total of 186 patients were referred; 37% were female, and the median age was 64 (51, 73) years. Dissections were classified as type A (43%), type B (18%), or a combination, and 55% had residual dissection. Over half (53%) did not start CR, with older age (aOR = 0.97: 95% CI, 0.94 - 0.99; P = .003), family history of aortic dissections and/or aneurysms (aOR = 0.17: 95% CI, 0.04 - 0.54; P = .005), and tobacco use (aOR = 0.35: 95% CI, 0.13 - 0.91; P = .037) being associated with lower odds of enrollment. Of the 87 who enrolled, 34 did so at a Mayo Clinic facility. There were no complications, with no difference in adverse outcomes. Among those with evaluations at graduation from CR (n = 21), quality of life (Dartmouth index 16 [14, 19] vs 25 [22, 30]; P = .002) and 6-minute walk distance (488 [375, 531] vs 302 [235, 398] m; P = .001) improved. Conclusions: Following thoracic aortic dissection repair, CR significantly improved quality of life and functional capacity without adverse events. Further work is needed to improve enrollment and establish data-driven safety margins for exercise.

Dynamic cerebral autoregulation (CA) refers to the brain's ability to maintain stable cerebral blood flow despite fluctuations in blood pressure (BP). Impaired CA has been associated with cardiovascular disease severity and cognitive decline. On the other hand, enhanced cardiorespiratory fitness appears to be protective against both cerebrovascular dysregulation and cognitive decline, with an unclear link between the two. However, among individuals with cardiovascular disease, the impact of exercise-based cardiac rehabilitation (CR) on CA remains unclear. Therefore, the aim of this study was to test the hypothesis that a 12-week CR program would improve dynamic CA in adults with CVD. To address this question, data were collected from 14 patients enrolled in the Mayo Clinic CR program following a cardiac-related hospital admission (age: 43-70 yrs; n=3 females), which included moderate-high intensity aerobic exercise 3 times/week for 12-weeks. Continuous measures of middle cerebral artery velocity (MCAv; transcranial doppler) and finger BP (photoplethysmography) were obtained during 3-minutes of rest and a 3-minute sit-to-stand protocol (0.025Hz frequency) pre- and post the CR program. Transfer function analyses were used to provide an index of dynamic CA. BP-MCAv coherence in the low frequency (LF) and very low frequency (vLF) domains at rest were not different pre- and post- CR (LF: 0.48±0.19 vs 0.43±0.16; P=0.54; vLF: 0.51±0.12 vs 0.47±0.16; P=0.14). Similarly, gain and phase values at rest were not different pre- and post- CR (gain LF: 0.66±0.37 vs 0.58±0.33; P=0.16; vLF: 0.87±0.53 vs 0.74±0.43; P=0.21; phase LF: 0.41±0.30 vs 0.43±0.26; P=0.64; vLF: 0.72±0.53 vs 0.66±0.16; P=0.18). In contrast, during the sit-to-stand protocol, coherence was lower following CR (pre vs post LF: 0.81±0.13 vs 0.79±0.16; p<0.01; vLF: 0.80±0.09 vs 0.79±0.14; p<0.01). In addition, gain was reduced post CR (pre vs post LF: 0.59±0.35 vs 0.55±0.31; P=0.02; vLF: 0.76±0.33 vs 0.61±0.37; p<0.01), suggesting CR-induced improvements in CA efficiency. However, phase remained unchanged pre- and post- CR during the sit-to-stand protocol (LF: 1.01±0.71 vs 0.84±0.58; P=0.17; vLF: 1.16±0.69 vs 1.08±0.60; P=0.19). Taken together, these findings demonstrate that a 12-week exercise-based CR program improves dynamic CA efficiency after a cardiac event. These novel results highlight the potential role of exercise training in improving cerebrovascular regulation. Funding: NIH AG073726 and Mayo Clinic This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Introduction: Sleep duration is now recognized as an important determinant of cardiovascular (CV) health. Recently, the CV implications of day-to-day variability in sleep duration have become apparent, with irregular sleep duration associated with increased risk of CV disease, including hypertension. However, the relationship between sleep duration variability and ambulatory blood pressure (BP) patterns in the general population or in patients with CV disease is unknown. Research Questions: We sought to investigate whether irregular sleep duration is associated with aberrant ambulatory BP or heart rate (HR) profiles in patients undergoing cardiac rehabilitation (CR). Methods: We recruited a sample of 42 patients with coronary artery disease enrolled in CR at Mayo Clinic Rochester. Participants underwent 24-hour ambulatory BP monitoring and sleep assessment including one week of wrist actigraphy and sleep diary prior to entering CR. Twenty-four hour, awake, and asleep averages were calculated for systolic BP, diastolic BP, and HR. Nocturnal dipping and morning surge were also computed for BP and HR. Sleep regularity was quantified by SD of actigraphy-derived sleep duration and irregular sleep duration was defined as SD >1 hour. Chi-square tests and Mann-Whitney U tests were used to compare groups. Results: Thirty-six participants (22% females, median age [25 th ,75 th IQR] 66.5 [61,75.8] years, body mass index 31.7 [26.9,35.1] kg/m 2 ) had valid actigraphy and ambulatory BP recordings. We found sleep duration SD >1 hour in 36% of them. Demographics and average sleep duration were similar between those with irregular and regular sleep duration (all Ps>0.11). Twenty-four-hour, awake and asleep HR values were comparable between groups (all Ps>0.26). Participants with irregular sleep duration exhibited lower nocturnal HR dipping (9.2 [3.1,11.6] % vs 12.9 [8.9,18.2] %, P=0.019) than their counterparts with regular sleep. Morning HR surge was also attenuated in patients with irregular sleep duration (3 [-1,9] bpm vs 10 [7,14] bpm, P=0.006). Ambulatory SBP and DBP measures did not differ significantly between groups (all Ps>0.17). Conclusions: High day-to-day variability in sleep duration is linked to blunted nocturnal dipping and morning surge in HR in patients with coronary artery disease enrolled in CR. Because altered ambulatory HR profile predicts unfavorable CV outcomes, evaluation of sleep patterns in the CR setting may yield important prognostic information.