Cardiopulmonary Exercise Stress Testing Research Articles

Application of non-invasive bioreactance to assess hemodynamic function in patients with hypertrophic cardiomyopathy.

Non-invasive technologies have become popular for the clinical evaluation of cardiac function. The present study evaluated hemodynamic response to cardiopulmonary exercise stress testing using bioreactance technology in patients with hypertrophic cardiomyopathy. The study included 29 patients with HCM (age 55 ± 15 years; 28% female) and 12 age (55 ± 14 years), and gender matched (25% female) healthy controls. All participants underwent maximal graded cardiopulmonary exercise stress testing with simultaneous non-invasive hemodynamic bioreactance and gas exchange. At rest, patients with HCM demonstrated significantly lower cardiac output (4.1 ± 1.3 vs. 6.1 ± 1.2 L/min; p < 0.001), stroke volume (61.5 ± 20.8 vs. 89.5 ± 19.8 mL/beat; p < 0.001), and cardiac power output (0.97 ± 0.3 vs. 1.4 ± 0.3watt; p < 0.001), compared to controls. At peak exercise, the following hemodynamic and metabolic variables were lower in HCM patients that is, heart rate (118 ± 29 vs. 156 ± 20 beats/min; p < 0.001), cardiac output (15.5 ± 5.8 vs. 20.5 ± 4.7 L/min; p = 0.017), cardiac power output (4.3 ± 1.6 vs. 5.9 ± 1.8 watts; p = 0.017), mean arterial blood pressure (126 ± 11 vs. 134 ± 10 mmHg; p = 0.039), and oxygen consumption (18.3 ± 6.0 vs. 30.5 ± 8.3 mL/kg/min; p < 0.001), respectively. Peak arteriovenous oxygen difference and stroke volume were not significantly different between HCM patients and healthy controls (11.2 ± 6.4 vs. 11.9 ± 3.1 mL/100 mL, p = 0.37 and 131 ± 50.6 vs. 132 ± 41.9 mL/beat, p = 0.76). There was a moderate positive relationship between peak oxygen consumption and peak heart rate (r = 0.67, p < 0.001), and arteriovenous oxygen difference (r = 0.59, p = 0.001). Functional capacity is significantly reduced in patients with HCM primarily due to diminished central (cardiac) rather than peripheral factors. Application of non-invasive hemodynamic assessment may improve understanding of the pathophysiology and explain mechanisms of exercise intolerance in hypertrophic cardiomyopathy.

Effect of Constant vs. Variable Moderate-Intensity Load on Peak Oxygen Uptake in Outpatient Cardiac Rehabilitation.

Background: In outpatient center-based cardiac rehabilitation (O-CBCR), moderate-intensity continuous training (MICT) based on the anaerobic threshold (AT) determined by cardiopulmonary exercise stress testing is recommended. However, it is unclear whether differences in exercise intensity within the MICT domain affect peak oxygen uptake (%peakV̇O2). Methods and Results: We retrospectively evaluated patients who underwent O-CBCR at Japan Community Healthcare Organization Osaka Hospital. Those treated with the constant-load method were designated as Group A (n=38), whereas those treated with the variable-load method were designated as Group B (n=48). Although the change in exercise intensity was significantly greater in Group B by approximately 4.5 W, the change in %peakV̇O2 was not significantly different between groups. Group A had a significantly longer exercise time than Group B (by approximately 4-5 min). No deaths or hospitalizations occurred in either group. The percentage of episodes with exercise cessation was similar between the 2 groups, but the percentage of episodes with load reduction was significantly higher in Group B, mostly because of the increased heart rate. Conclusions: In supervised MICT based on AT, the variable-load method increased exercise intensity more than the constant-load method without severe complications, but did not improve %peakV̇O2.

A computational predictor of the anaerobic mechanical power outputs from a clinical exercise stress test.

We previously were able to predict the anaerobic mechanical power outputs using features taken from a maximal incremental cardiopulmonary exercise stress test (CPET). Since a standard aerobic exercise stress test (with electrocardiogram and blood pressure measurements) has no gas exchange measurement and is more popular than CPET, our goal, in the current paper, was to investigate whether features taken from a clinical exercise stress test (GXT), either submaximal or maximal, can predict the anaerobic mechanical power outputs to the same level as we found with CPET variables. We have used data taken from young healthy subjects undergoing CPET aerobic test and the Wingate anaerobic test, and developed a computational predictive algorithm, based on greedy heuristic multiple linear regression, which enabled the prediction of the anaerobic mechanical power outputs from a corresponding GXT measures (exercise test time, treadmill speed and slope). We found that for submaximal GXT of 85% age predicted HRmax, a combination of 3 and 4 variables produced a correlation of r = 0.93 and r = 0.92 with % error equal to 15 ± 3 and 16 ± 3 on the validation set between real and predicted values of the peak and mean anaerobic mechanical power outputs (p < 0.001), respectively. For maximal GXT (100% of age predicted HRmax), a combination of 4 and 2 variables produced a correlation of r = 0.92 and r = 0.94 with % error equal to 12 ± 2 and 14 ± 3 on the validation set between real and predicted values of the peak and mean anaerobic mechanical power outputs (p < 0.001), respectively. The newly developed model allows to accurately predict the anaerobic mechanical power outputs from a standard, submaximal and maximal GXT. Nevertheless, in the current study the subjects were healthy, normal individuals and therefore the assessment of additional subjects is desirable for the development of a test applicable to other populations.

Moderators of peak respiratory exchange ratio during exercise testing in children and adolescents with Fontan physiology.

Many patients with Fontan physiology are unable to achieve the minimum criteria for peak effort during cardiopulmonary exercise testing. The purpose of this study is to determine the influence of physical activity and other clinical predictors related to achieving peak exercise criteria, signified by respiratory exchange ratio ≥ 1.1 in youth with Fontan physiology. Secondary analysis of a cross-sectional study of 8-18-year-olds with single ventricle post-Fontan palliation who underwent cardiopulmonary exercise testing (James cycle protocol) and completed a past-year physical activity survey. Bivariate associations were assessed by Wilcoxon rank-sum test and simple regression. Conditional inference forest algorithm was used to classify participants achieving respiratory exchange ratio > 1.1 and to predict peak respiratory exchange ratio. Of the n = 43 participants, 65% were male, mean age was 14.0 ± 2.4 years, and 67.4% (n = 29) achieved respiratory exchange ratio ≥ 1.1. Despite some cardiopulmonary exercise stress test variables achieving statistical significance in bivariate associations with participants achieving respiratory exchange ratio > 1.1, the classification accuracy had area under the precision recall curve of 0.55. All variables together explained 21.4% of the variance in respiratory exchange ratio, with peak oxygen pulse being the most informative. Demographic, physical activity, and cardiopulmonary exercise test measures could not classify meeting peak exercise criteria (respiratory exchange ratio ≥ 1.1) at a satisfactory accuracy. Correlations between respiratory exchange ratio and oxygen pulse suggest the augmentation of stroke volume with exercise may affect the Fontan patient's ability to sustain high-intensity exercise.

Exercise oxygen desaturation is a predictor of cardiopulmonary complications after lung resection

BackgroundTo investigate whether oxygen desaturation during low technology tests was associated with complications after lung resection.MethodsA retrospective cohort study was conducted on 1097 candidates for pulmonary resection; seven metabolic equivalents...

Comparison of Incremental Shuttle Walking Test, 6-Minute Walking Test, and Cardiopulmonary Exercise Stress Test in Patients with Myocardial Infarction.

BACKGROUND This study aimed to analyze the correlations among peak oxygen uptake (VO2) in cardiopulmonary exercise test (CPX), incremental shuttle walking test (ISWT), and 6-minute walking test (6MWT) distances in patients with myocardial infarction (MI). Additionally, we aimed to determine the relationship between the maximum heart rate (HRmax) and the rate of perceived exertion (RPE) among the tests and compare the changes in heart rate to verify the clinical benefit of the submaximal stress test. MATERIAL AND METHODS We analyzed the correlation by using the ISWT and 6MWT at 30-min intervals after 24 h of CPX in patients with MI. The differences in HRmax and RPE between the tests were also compared. Additionally, changes in heart rate were analyzed using descriptive statistics. RESULTS The ISWT distance was more strongly correlated with peak VO₂ (r=.823: 95% CI, 0.681-0.910) than was 6MWT (r=0.776: 95% CI, 0.683-0.870). HRmax in the CPX demonstrated a significant correlation with that in the ISWT and 6MWT (P<0.05), with the ISWT (r=0.815: 95% CI, 0.451-0.996) having a stronger correlation than the 6MWT (r=0.664: 95% CI, 0.146-0.911). The value of RPE was significantly different (P<0.05); however, there was no significant correlation. Changes in heart rate in the 6MWT plateaued after the initial increase, while the heart rate in the ISWT and CPX increased gradually. CONCLUSIONS We recommend the ISWT as a submaximal exercise test to evaluate exercise capacity in patients with MI.

THE INFLUENCE OF SUDDEN VIGOROUS PHYSICAL EXERTION ON CARDIAC DEMAND UNDER AMBULATORY CONDITIONS AMONG FIREFIGHTERS

Firefighters have a high prevalence of cardiovascular disease and its risk factors compared to the general population. The poor heart health of firefighters is implicated in their increased risk of sudden cardiac death (SCD) accounting for nearly 50% of all on-duty fatalities. Exercise may confer protective benefits against SCD in part due to the immediate blood pressure (BP) reductions of 5-8 mmHg following exercise, termed postexercise hypotension (PEH). PURPOSE: To examine the time course of PEH under ambulatory conditions after a maximal cardiopulmonary graded exercise stress test (GEST) among career firefighters. METHODS: Firefighters (n = 19) completed a maximal GEST and a non-exercise control (CONTROL) in random order on separate nonwork days and left the laboratory attached to an ambulatory BP (ABP) monitor for 19 hr. Ambulatory systolic BP (ASBP), diastolic BP (ADBP), and heart rate (AHR) were recorded at hourly intervals over 19 hr. The ambulatory rate pressure product (ARPP), an indicator of cardiac demand, was calculated as ASBPxAHRx10-3 at each hourly interval over 19 hr. Repeated measures ANCOVA tested if the ABP, AHR, and ARPP responses differed after GEST vs CONTROL over 19 hr. RESULTS: Firefighters were middle-aged (39.5 ± 8.9 yr), overweight (29.2 ± 4.0 kg/m2) men with elevated resting BP (123.1 ± 9.6/79.8 ± 10.4 mmHg), while resting HR (67.7 ± 11.3 bpm) and RPP (8.4 ± 1.7 mmHg*bpm*10-3) were in normal ranges. ASBP (16.6 ± 5.7 mmHg) and ADBP (3.1 ± 4.6 mmHg) increased after the GEST vs CONTROL over 19 hr (ps < 0.01), as did AHR (9.4 ± 7.9 bpm, p = 0.02) and ARPP (2.5 ± 1.1 mmHg*bpm*10-3, p < 0.01). CONCLUSION: Unexpectedly, the firefighters exhibited postexercise hypertension rather than PEH. The increases in ABP and AHR we observed resulted in a sustained increase in cardiac demand. Further investigation is needed to confirm our findings and determine whether the adverse hemodynamic responses we observed contribute to the high prevalence of SCD that firefighters experience on the job.

Centres of sports cardiology in Czechia - first experiences

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Sports cardiology is a subspeciality of cardiology. It differs from general cardiology practice; the presence of an athlete’s heart can be challenging to differentiate from incipient cardiac pathologies, and athletes often present with atypical symptoms and expectations. In Czechia, three Centres of Sports Cardiology (CSC) for athletes older than 15 years and one for children were founded 2020 and endorsed by the Czech Society of Cardiology and the Czech Society of Sports medicine. Purpose The present study aims to share our experience from the first two years of functioning two tertiary sport cardiology centres (Centre 1 and Centre 2) Methods Only athletes registered for the examination from 1st January 2020 till 7th November 2021 were included. Results We included 149 athletes (79 from Centre 1 and 71 from Centre 2). The mean age was 29 ± 13 years. The majority of sports were mixed (n= 83) than endurance (n=58) and very few power (n=3) and skill sports (n=1). The main reason for examination was abnormal preparticipation screening results (n=46), symptoms (n=45) and abnormal findings on complementary examination (n=31). Only two athletes were indicated from cascade screening and one athlete after sudden cardiac arrest. In CSC we performed electrocardiograms (n=101), echocardiography (n=77), HolterECG (n=39), 24-hour ambulatory blood pressure monitoring (n=3), cardiac magnetic resonance (n=13) one CT-coronary angiography, cardiopulmonary exercise stress test (n=41), invasive coronary angiography (n=3), other examination (n=15). We were able to ascertain a diagnosis in 113 athletes; a suspected diagnosis was in 14 athletes, and in 20, we were unable to set any diagnosis. The main conclusions were that 79 (53%) of athletes were eligible to sport participation, in 34 (23%) of athletes, the eligibility had a condition, and only 10 (6.7 %) athletes were ineligible to sport participation. (However, the main conclusions were that 79 (53%) of athletes were eligible to sport participation, in 34 (23%) of athletes, the eligibility had a condition, and only 10 (6.7 %) athletes were ineligible to sport participation. ) The ineligibility was due to cardiomyopathy (n=5), long QT syndrome (n=2), valvular heart disease (n=1), Marfan syndrome (n=1), preexcitation syndrome (n=1). Only six athletes were lost to follow-up, and in 13 (8.7 %), the examination process was not yet closed. Conclusion(s) The establishment of sports cardiology centres in Czechia respects the global trend in cardiovascular care for athletes. The first 22 months of their work confirm the importance of their existence with the centralization of subspecialty cardiology care. Confirmation of the trend is the establishment of full eligibility in 76% of examined athletes. Similarly, the non-recommendation of further sports activity in less than 7% of examined athletes again confirms the correctness of the existence of sports cardiology centres.

Cardiopulmonary Exercise Performance in the Pediatric and Young Adult Population Before and During the COVID-19 Pandemic.

Physical activity (PA) decreased and sedentary behavior (SB) increased in the pediatric population during the Coronavirus Disease 2019 (COVID-19) pandemic. We examined the effects of PA and SB on cardiopulmonary exercise performance in children, adolescents and young adults both with and without underling cardiac disease, and hypothesized that there will be a change in aerobic and physical working capacity during the pandemic. This was a single-center retrospective longitudinal cohort study in patients age 6–22 years who underwent serial maximal cardiopulmonary exercise stress testing before and during the COVID-19 pandemic. Metabolic variables were obtained; PA and SB data were extracted from clinic notes. A total of 122 patients (60% male) underwent serial exercise testing with a median age of 14 years at the first CPET. Predicted peak aerobic capacity significantly decreased among both females and males during the pandemic, even after adjusting for changes in somatic growth. There was no significant change in physical working capacity during the pandemic. Patients who were more aerobically fit experienced a greater decrease in aerobic capacity during the pandemic compared to those less fit. In conclusion, cardiopulmonary exercise performance, notably aerobic activity, decreased during the COVID-19 pandemic in children, adolescents and young adults compared to pre-pandemic values. This decline was most notable in those with the highest pre-pandemic aerobic capacity values and was independent of somatic growth or changes in BMI. This study has public health implications and demonstrates the importance of PA on overall cardiovascular health.

Granulomatous Myocarditis After Cardiac Transplantation for Giant Cell Myocarditis

<h3>Introduction</h3> Cardiac sarcoidosis and idiopathic giant cell myocarditis are uncommon but serious inflammatory cardiomyopathies which share some clinical and histopathologic features. We present the case of a patient who developed end-stage heart failure due to giant cell myocarditis requiring heart transplant, and years after transplantation, developed cardiac sarcoidosis <h3>Case Report</h3> A 45-year-old man with no significant medical history was preparing for a triathlon but began to experience subacute heart failure symptoms culminating in a sudden cardiac arrest shortly after endomyocardial biopsy (EMBx) revealing giant cell myocarditis. He required ECMO cannulation as a bridge to biventricular HeartWare HVADs and was treated with cyclosporin. After 10 months of biventricular support, he underwent heart transplant. Post-operative course was uneventful and was maintained on standard immunosuppression with tacrolimus, mycophenolate, and prednisone. At three-years post-transplant, he was transitioned to sirolimus and remained stable. During his sixth annual visit, he noted exertional intolerance. His echocardiogram revealed a drop in his left ventricular ejection fraction from 58% to 47%, an increase LVIDd from 41 mm to 51 mm, and an increase in LV mass index from 70 to 80 g/m2. He also had a cardiopulmonary exercise stress test and his peak VO2 went from 36 ml/(min/kg) to 32.9 (ml/min/kg). Event monitor showed PVC's and non-sustained VT. Coronary angiogram showed mild non obstructive cardiac allograft vasculopathy. Endomyocardial biopsy revealed an active granulomatous myocarditis which had the appearance of sarcoidosis. His steroid regimen was augmented to prednisone 30 mg daily, then tapered. Three months after immunosuppression changes, cardiac PET scan revealed findings compatible with an inflammatory cardiomyopathy process associated with edema, fibrosis and scar. Tacrolimus was added to his regimen, mycophenolate dose was increased and received 3 days of pulse dose steroids <h3>Summary</h3> While previous descriptions of recurrent sarcoidosis in cardiac allografts have been described, the unique features of GCM on native heart explantation and clear features of sarcoidosis in the allograft despite adequate immunosuppression highlight not only the challenges with regard to management of active myocarditis after transplant but also the overlap of the two disease entities

Hemodynamic Gain Index Is An Independent Predictor Of Adverse Clinical Outcomes In Patients With Heart Failure With Reduced Ejection Fraction Undergoing Cardiopulmonary Exercise Stress Test

<h3>Introduction</h3> Recently, the hemodynamic gain index (HGI), a simple parameter calculated from resting and peak systolic blood pressure (SBP) and heart rate (HR) during exercise stress testing without a metabolic cart, was shown to be an independent predictor of mortality. However, the prognostic implications of the HGI in patients with heart failure with reduced ejection fraction (HFrEF) have not been well studied. <h3>Hypothesis</h3> We hypothesized that lower HGI is independently associated with adverse outcomes in the entire cohort and in subgroups of patients with HFrEF and comparable to peak VO2 in risk stratification. <h3>Method</h3> Electronic medical records of 954 HFrEF patients (LVEF ≤40%) undergoing cardiopulmonary exercise stress test from December 2012 to September 2020 were reviewed. HGI was calculated using the formula, [(SBP_peak x HR_peak)-(SBP_rest x HR_rest)]/(SBP_rest x HR_rest). We excluded patients who had a negative HGI, hypotensive, or bradycardic response. The primary outcome was the composite of all-cause mortality, LVAD implantation, or heart transplantation. Multivariable Cox proportional hazard models and the log rank test were used for statistical comparisons. Subgroups of HFrEF were stratified by respiratory exchange ratio (RER) of 1.05, median age, sex, body mass index (BMI) of 35 kg/m², and beta-blocker use. <h3>Results</h3> In our study cohort (mean age 56.3±12.0 years, 72% men, 86% with beta-blockers, mean LVEF 24.6 ±7.9%, 17% with BMI ≥35 kg/m², 73% with RER >1.05), there were 331 (34.7%) patients who met the primary outcome during a median follow up time of 946 days. After adjustment for age, sex, comorbidities, and LVEF, lower HGI was independently associated with greater risk of the primary outcome(quartile 1 vs 4, HR 2.89, 95% CI 2.00-4.20, <i>p</i><0.001, <b>Figure 1A</b>). There is no difference in the association between HGI and risk by subgroup (<b>Figure 1B</b>). The HGI was also comparable to peak VO₂ in terms of primary outcome prediction (AUC 0.69 [95%CI 0.65-0.72] vs 0.70 [95%CI 0.66-0.73], <i>p</i>=0.777). <h3>Conclusion</h3> In this well-characterized, contemporary cohort of patients with HFrEF undergoing CPET evaluation, lower HGI is independently associated with a greater risk of death, LVAD implantation and heart transplantation. The prognostic value of HGI was comparable to that of peak VO2, suggesting it may have a potential clinical utility in risk stratification when considering advanced heart failure therapies.

Sarcoidosis: Hiding in Plain Sight

<h3>Introduction</h3> Sarcoidosis is a systemic disease that can masquerade as many conditions. Due to its often patchy distribution, myocardial biopsy is only ∼30% sensitive. Herein we present a case of sarcoidosis diagnosed from an extra-cardiac biopsy years after the onset of cardiomyopathy. <h3>Case Report</h3> A 54 year old man initially presented with dyspnea and fatigue due to new onset HFrEF of 20%. He had a significant family history of SCD. His workup revealed non-obstructive CAD, a myxomatous mitral valve with bileaflet prolapse and moderate regurgitation, and a cystic structure attached to the tricuspid valve. Given his frequent ventricular ectopy, he was discharged on guideline therapy for HFrEF and a wearable cardioverter defibrillator. Genetic testing for dilated cardiomyopathies revealed EYA4 and TTN variants of unknown significance. A cardiac MRI a few months later demonstrated no abnormal late gadolinium enhancement and persistent systolic dysfunction, so he underwent AICD implant. His course was further complicated by recurrent admissions for supraventricular and ventricular tachyarrhythmias. A cardiopulmonary exercise stress test demonstrated low-risk results. Further evaluation noted prolonged AV conduction. A RHC revealed mild post-capillary pulmonary hypertension and a mildly decreased cardiac index at 2.01 L/min/m². Months later, he underwent CRT-D upgrade. He started improving functionally until he developed left eyelid swelling, initially thought to be lymphoma. An orbital biopsy revealed non-caseating granulomas. A PET/CT demonstrated FDG uptake within subcarinal lymph nodes but no cardiac uptake. Initially he declined immunomodulatory therapy, but as his symptoms worsened, he started corticosteroids and transitioned to mycophenolate mofetil due to intolerance of methotrexate. Due to disease progression on repeat FDG-PET, he was switched to infliximab. <h3>Summary</h3> The diagnosis of sarcoidosis can be difficult due to its variable presentation, including heart block, heart failure, ventricular arrhythmias and sudden cardiac death. Cardiac involvement occurs in 25% of cases. Our case was complicated by a cMRI that was negative for cardiac involvement, which emphasizes the importance of complimentary inflammatory imaging with FDG-PET. A multidisciplinary approach is needed that engages sarcoid specialists for earlier diagnosis to ensure rapid initiation of therapy to reduce end-organ dysfunction.

Abstract 12310: Metabolic Gain Index is Associated With Adverse Clinical Outcomes Independently of Peak VO 2 in Patients With Heart Failure With Reduced Ejection Fraction Undergoing Cardiopulmonary Exercise Stress Testing

Introduction: Cardiopulmonary exercise stress test (CPET) is an essential prognostic tool in patients with heart failure with reduced ejection fraction (HFrEF) for advanced therapy evaluation. We studied the predictive utility of the metabolic gain index (MGI), which reflects the relative gain of the CPET-estimated stroke volume by the relative change in the product of VO 2 and heart rate (HR) from resting to peak exercise. This novel MGI aims to reflect cardiac reserve function, and, overall prognosis in HFrEF patients. Hypothesis: The MGI is an independent predictor of adverse outcomes in patients with HFrEF. Methods: We reviewed electronic medical records of 843 HFrEF patients (LVEF ≤40%) undergoing CPET from 12/2012 to 9/2020. The MGI was calculated using the formula, [(Peak VO 2 x Peak HR)-(Resting VO 2 x Resting HR)]/(Resting VO 2 x Resting HR). Patients with hypotensive or bradycardia response during exercise were excluded. Primary outcome was the composite of all-cause mortality, LVAD implantation, and heart transplantation. Multivariable Cox proportional hazard models and log rank test were used. For subgroup analysis, patients were stratified by the RER, age, sex, BMI, and beta-blocker use. Results: In our study cohort (mean age 56.2±12.2 years, 73% men, 85% with beta-blockers, mean LVEF 24.8±8.0 %, 16% with BMI ≥35 kg/m 2 , and 75% with RER &gt;1.05), there were 279 (33.1%) patients developed adverse events during median follow up time of 897 days. Lower MGI was independently associated with increased risk of the adverse outcomes with adjustment for age, sex, comorbidities, LVEF, and peak VO 2 (quartile 1 vs 4, hazard ratio 1.83, 95% CI 1.03-3.25, p =0.040, Figure 1A ), especially in patients with RER &gt; 1.05, BMI &lt; 35 kg/m 2 , and without beta-blocker use ( Figure 1B ). Conclusions: Lower MGI is associated with poor prognosis independently of peak VO 2 . The prognostic value of MGI needs to be further corroborated in other multicenter HFrEF cohorts.

Prognostic value of the hemodynamic gain index in different groups of patients undergoing cardiopulmonary exercise stress testing

Abstract Background A novel hemodynamic parameter obtained from the cardiopulmonary exercise testing (CPET), the hemodynamic gain index (HGI), was developed and shown to be a strong independent predictor of all-cause mortality in a large male cohort. The HGI also strongly correlates with exercise parameters such as peak oxygen consumption and metabolic equivalents (METs). However, prognostic implications of the HGI have not been externally validated with subgroup analyses based on sex, heart failure (HF), coronary artery disease (CAD) and the use of beta-blockers. Purpose We aimed to validate the prognostic value of the HGI in men, women, and patients with and without HF, CAD, and beta-blocker use. Methods We identified 126,356 consecutive patients undergoing treadmill exercise testing for symptom evaluation between 1/1/1991–02/27/2015. HGI was calculated using the formula, [(SBPpeak x HRpeak) − (SBPrest x HRrest)] / (SBPrest x HRrest). Univariable and multivariable cox regression models were used to determine the associations between the HGI stratified by quartiles and all-cause mortality at 10 years with adjustment for cardiovascular risk factors (age, sex, diabetes, hypertension, dyslipidemia, chronic kidney disease, smoking status and body mass index) and exercise testing parameters (chronotropic reserve index, METs, abnormal heart rate recovery, and total exercise time). Results In our study cohort, mean age was 53.5±12.6 years. There were 74,724 (59.1%) male, 5,940 (4.7%) HF, 21,123 (16.7%) CAD, and 30,568 (24.2%) beta-blocker-using patients. During the mean follow up of 8.7 years, 9,929 (7.9%) died. Mean HGI was 2.0±1.2 bpm/mmHg. Lower HGI was associated with all-cause mortality in the entire cohort (Figure 1A, log rank p&amp;lt;0.001). After adjustment for the covariates, the lowest quartile of the HGI was independently associated with all-cause mortality in subgroups of men, women, and patients with and without HF, CAD, and beta-blocker use (Figure 1B, all p≤0.001) compared with the highest quartile of the HGI. Conclusions HGI is an independent predictor of long-term mortality after adjusted for traditional cardiovascular risk factors, and exercise performance across patient subgroups. Funding Acknowledgement Type of funding sources: None. Figure 1. Kaplan-Meier curve and Cox regression

Systems analysis of the mechanisms governing the cardiovascular response to changes in posture and in peripheral demand during exercise

Blood flows and pressures throughout the human cardiovascular system are regulated in response to various dynamic perturbations, such as changes to peripheral demands in exercise, rapid changes in posture, or loss of blood from hemorrhage, via the coordinated action of the heart, the vasculature, and autonomic reflexes. To assess how the systemic and pulmonary arterial and venous circulation, the heart, and the baroreflex work together to effect the whole-body responses to these perturbations, we integrated an anatomically-based large-vessel arterial tree model with the TriSeg heart model, models capturing nonlinear characteristics of the large and small veins, and baroreflex-mediated regulation of vascular tone and cardiac chronotropy and inotropy. The model was identified by matching data from the Valsalva maneuver (VM), exercise, and head-up tilt (HUT). Thirty-one parameters were optimized using a custom parameter-fitting tool chain, resulting in an unique, high-fidelity whole-body human cardiovascular systems model. Because the model captures the effects of exercise and posture changes, it can be used to simulate numerous clinical assessments, such as HUT, the VM, and cardiopulmonary exercise stress testing. The model can also be applied as a framework for representing and simulating individual patients and pathologies. Moreover, it can serve as a framework for integrating multi-scale organ-level models, such as for the heart or the kidneys, into a whole-body model. Here, the model is used to analyze the relative importance of chronotropic, inotropic, and peripheral vascular contributions to the whole-body cardiovascular response to exercise. It is predicted that in normal physiological conditions chronotropy and inotropy make roughly equal contributions to increasing cardiac output and cardiac power output during exercise. Under upright exercise conditions, the nonlinear pressure-volume relationship of the large veins and sympathetic-mediated venous vasoconstriction are both required to maintain preload to achieve physiological exercise levels. The developed modeling framework is built using the open Modelica modeling language and is freely distributed.

COVID-19: the new cause of dyspnoea as a result of reduced lung and peripheral muscle performance

This study aimed to evaluate the cardiopulmonary function and impairment of exercise endurance in patients with COVID-19 after 3 months of the second wave of the pandemic in Turkey. A total of 51 consecutive COVID-19 survivors, mostly healthcare providers, still working in the emergency room and intensive care units of the hospital after the second wave of Covid 19 pandemia were included in this study. Cardiopulmonary exercise stress test was performed. The median of the exercise time of the COVID-19 survivors, was 10 (4.5–13) minutes and the mean 6.8 ± 1.3 Mets was achieved. The VO2 max of the COVID-19 survivors was 24 ± 4.6 ml kg−1 min−1 which corresponds the 85 ± 10% of the predicted VO2 max value. The VO2WRs value which was reported about 8.5–11 ml min−1 per watt in healthy individuals as normal was found lower in Covid 19 survivors (5.6 ± 1.4). The percentage of the maximum peak VO2 calculated according to the predictable peak VO2 of the COVID-19 survivors, was found significantly lower in male patients (92 ± 9.5% vs 80 ± 8.5%, p: 0.000). Also, there was a positive correlation between the percentage of the maximum predicted VO2 measurements and age (r: 0.320, p: 0000). The peak VO2 values of COVID-19 survivors decreased, and simultaneously, their exercise performance decreased due to peripheral muscle involvement. We believe that COVID-19 significantly affects men and young patients.

COVID-19 Pandemic: Clinical Guidance for Aerobic Exercise-Based Stroke Rehabilitation

Objective(s)1) To discuss the implications of COVID-19 for exercise in the setting of stroke rehabilitation and 2) to guide and inform the clinical implementation of evidence-based aerobic exercise in stroke rehabilitation.Data SourcesA literature search was conducted using 4 databases: MEDLINE, EMBASE, PsycINFO, and AMED Allied and Complementary Medicine, from inception to January 27th, 2021.Study SelectionWe utilized keywords related to COVID-19, exercise, rehabilitation, and included published athletic return to play after COVID-19 infection and clinical practice guidelines on exercise-based recommendations for COVID-19. Out of 391 published articles, none were related to exercise recommendations and stroke rehabilitation in the context of the COVID-19 pandemic.Data ExtractionIn the absence of stroke-specific guidance, we drew upon pre-COVID clinical practice aerobic exercise guidelines for stroke (n=2) and COVID-19 exercise recommendations for other populations (e.g., athletic [n=6], pulmonary [n=1] and cardiac rehabilitation [n=2]).Data SynthesisClinical considerations were developed for hospital and out-patient settings to outline safety considerations to reduce the risk of viral transmission and implementation strategies for pre-participation screening, prescription, and progression of aerobic exercise for symptomatic and asymptomatic cases of COVID-19. Based on limited evidence, we suggest that cardiopulmonary exercise stress testing with electrocardiography be conducted following COVID-19 infection and identify subjective and physiological measures to guide decision making regarding the suitability and prescription of aerobic exercise. Finally, we recommend that clinicians and researchers stay abreast with the literature to implement evidence-based practice relating to stroke, aerobic exercise, and COVID-19.ConclusionsUsing a patient and clinician approach, we have developed COVID-19 specific guidance as a framework for restoring aerobic exercise implementation in stroke rehabilitation settings.Author(s) DisclosuresNo conflicts of interest.

Relationship between cardiorespiratory fitness and preoperative evaluation findings in patients with morbid obesity undergoing sleeve gastrectomy: A cross-sectional study.

Evaluating various parameters, including preoperative cardiorespiratory fitness markers, is critical for patients with morbid obesity. Also, clinicians should prescribe suitable exercise and lifestyle guideline based on the tested parameters. Therefore, we investigated cardiorespiratory fitness and its correlation with preoperative evaluation in patients with morbid obesity scheduled for laparoscopic sleeve gastrectomy.A retrospective cross-sectional study was conducted with 38 patients (13 men and 25 women; mean age, 34.9 ± 10.9 years) scheduled for laparoscopic sleeve gastrectomy. Cardiopulmonary exercise stress tests were also performed. Measured cardiopulmonary responses included peak values of oxygen consumption (VO2), metabolic equivalents (METs), respiratory exchange ratio, heart rate (HR), and rate pressure product. Body composition variables were analyzed using bioimpedance analysis, laboratory parameters (hemoglobin A1c, lipid profile, inflammatory markers), and comorbidities. In addition, self-reported questionnaires were administered, including the Beck Depression Inventory (BDI), Hamilton Depression Rating Scale (HDRS), Short-Form Health Survey (SF-36), and Moorehead-Ardelt Quality of Life Questionnaire (MAQOL).The average body mass index (BMI) and percent body fat were 39.8 ± 5.7 kg/m−2 and 46.2 ± 6.1%, respectively. The VO2peak/kg, METs, RERpeak, HRpeak, RPPpeak, age-predicted HR percentage, and VO2peak percentage were 18.6 ± 3.8 mL/min−1/kg−1, 5.3 ± 1.1, 1.1 ± 0.1, 158.5 ± 19.8, 32,414.4 ± 6,695.8 mm Hg/min−1, 85.2 ± 8.8%, and 76.1 ± 14.8%, respectively. BMI (P = .026), percent body fat (P = .001), HRpeak (P = .018), erythrocyte sedimentation rate (P = .007), total BDI (P = .043), HDRS (P = .025), SF-36 (P = .006), and MAQOL (P = .007) scores were significantly associated with VO2peak/kg. Body fat percentage (P < .001) and total SF-36 score (P < .001) remained significant in the multiple linear regression analysis.Various cardiorespiratory fitness markers were investigated in patients with morbid obesity who underwent the sleeve gastrectomy. Peak aerobic exercise capacity was significantly associated with preoperative parameters such as body fat composition and self-reported quality of life in these patients. These results could be utilized for preoperative and/or postoperative exercise strategies in patients with morbid obesity scheduled for laparoscopic sleeve gastrectomy.

Reverse Myocardial Remodeling Following Valve Repair in Patients With Chronic Severe Primary Degenerative Mitral Regurgitation

ObjectivesThe aims of this study were to quantify preoperative myocardial fibrosis using late gadolinium enhancement (LGE), extracellular volume fraction (ECV%), and indexed extracellular volume (iECV) on cardiac magnetic resonance; determine whether this varies following surgery; and examine the impact on postoperative outcomes. BackgroundMyocardial fibrosis complicates chronic severe primary mitral regurgitation and is associated with left ventricular dilatation and dysfunction. It is not known if this nonischemic fibrosis is reversible following surgery or if it affects ventricular remodeling and patient outcomes. MethodsA multicenter prospective study was conducted among 104 subjects with primary mitral regurgitation undergoing mitral valve repair. Cardiac magnetic resonance and cardiopulmonary exercise stress testing were performed preoperatively and ≥6 months after surgery. Symptoms were assessed using the Minnesota Living With Heart Failure Questionnaire. ResultsMitral valve repair was performed for Class 2a indications in 65 patients and Class 1 indications in 39 patients. Ninety-three patients were followed up at 8.8 months (IQR: 7.4 months-10.6 months). Following surgery, there were significant reductions in both ECV% (from 27.4% to 26.6%; P = 0.027) and iECV (from 17.9 to 15.4 mL/m2; P < 0.001), but the incidence of LGE was unchanged. Neither preoperative ECV% nor LGE affected postoperative function, but iECV predicted left ventricular end-systolic volume index (β = 1.04; 95% CI: 0.49 to 1.58; P < 0.001) and left ventricular ejection fraction (β = −0.61; 95% CI: −1.05 to −0.18; P = 0.006). Patients with above-median iECV of ≥17.6 mL/m2 had significantly larger postoperative values of left ventricular end-systolic volume index (30.5 ± 12.7 mL/m2 vs 23.9 ± 8.0 mL/m2; P = 0.003), an association that remained significant in subcohort analyses of patients in New York Heart Association functional class I. ConclusionsMitral valve surgery results in reductions in ECV% and iECV, which are surrogates of diffuse myocardial fibrosis, and preoperative iECV predicts the degree of postoperative remodeling irrespective of symptoms. (The Role of Myocardial Fibrosis in Degenerative Mitral Regurgitation; NCT02355418)

Exercise Capacity in Young Adults Born Small for Gestational Age

Being born small for gestational age (SGA), approximately 10% of all births, is associated with increased risk of cardiovascular mortality in adulthood, but mechanistic pathways are unclear. Cardiac remodeling and dysfunction occur in fetuses SGA and children born SGA, but it is uncertain whether and how these changes persist into adulthood. To evaluate baseline cardiac function and structure and exercise capacity in young adults born SGA. This cohort study conducted from January 2015 to January 2018 assessed a perinatal cohort born at a tertiary university hospital in Spain between 1975 and 1995. Participants included 158 randomly selected young adults aged 20 to 40 years born SGA (birth weight below the 10th centile) or with intrauterine growth within standard reference ranges (controls). Participants provided their medical history, filled out questionnaires regarding smoking and physical activity habits, and underwent incremental cardiopulmonary exercise stress testing, cardiac magnetic resonance imaging, and a physical examination, with blood pressure, glucose level, and lipid profile data collected. Being born SGA. Cardiac structure and function assessed by cardiac magnetic resonance imaging, including biventricular end-diastolic shape analysis. Exercise capacity assessed by incremental exercise stress testing. This cohort study included 81 adults born SGA (median age at study, 34.4 years [IQR, 30.8-36.7 years]; 43 women [53%]) and 77 control participants (median age at study, 33.7 years [interquartile range (IQR), 31.0-37.1 years]; 33 women [43%]). All participants were of White race/ethnicity and underwent imaging, whereas 127 participants (80% of the cohort; 66 control participants and 61 adults born SGA) completed the exercise test. Cardiac shape analysis showed minor changes at rest in right ventricular geometry (DeLong test z, 2.2098; P = .02) with preserved cardiac function in individuals born SGA. However, compared with controls, adults born SGA had lower exercise capacity, with decreased maximal workload (mean [SD], 180 [62] W vs 214 [60] W; P = .006) and oxygen consumption (median, 26.0 mL/min/kg [IQR, 21.5-33.5 mL/min/kg vs 29.5 mL/min/kg [IQR, 24.0-36.0 mL/min/kg]; P = .02). Exercise capacity was significantly correlated with left ventricular mass (ρ = 0.7934; P < .001). This cohort of young adults born SGA had markedly reduced exercise capacity. These results support further research to clarify the causes of impaired exercise capacity and the potential association with increased cardiovascular mortality among adults born SGA.