Cardiopulmonary Stress Testing Research Articles

Natural shear wave elastography reveals hidden cardiac dysfunction in adult survivors of childhood cancer during cardiopulmonary stress testing

Abstract Background Hidden cardiotoxicity in adult survivors of childhood cancer may carry significant prognostic implications. Many of these survivors are asymptomatic at rest but show impaired cardiorespiratory fitness during exercise. Stress echocardiography combined with cardiopulmonary exercise testing (CPET) can reveal hidden diastolic dysfunction, although it presents major challenges. High frame rate (HFR) natural shear wave (SW) imaging is emerging as an innovative method for assessing myocardial stiffness, a key determinant of diastolic function. Purpose We investigated the relationship between natural SW measured at rest as a marker of myocardial stiffness and patient performance during CPET as markers of cardiorespiratory fitness. Methods A total of 115 subjects; 72 cancer survivors (mean age 20 ±4 years) and 43 matched healthy volunteers (HV) were recruited. We acquired both conventional as well as high frame rate echocardiographic images (ca. 1200 frames/second) at rest. During an incremental, symptom-limited cardiopulmonary exercise test on a treadmill, both peak and efficiency of oxygen consumption (VO2 peak and VO2/work slope) were recorded. All HFR data were analysed offline by drawing an anatomical M-mode along the ventricular septum in the parasternal long axis view, colour coded for tissue acceleration. SW after mitral valve closure (MVC) appeared as green bands and their velocities were measured by estimating the slope semi-automatically. Results In our survivors’ cohort, the prevalence of cardiac dysfunction based on reduced global longitudinal strain was 9.7%. In a univariate regression model, predictors of peak VO2 were age, body mass index (BMI), systolic blood pressure (SBP), left ventricular end-diastolic diameter (LVEDD), left atrial volume indexed (LAVi), mitral inflow to mitral relaxation velocity ratio (E/e’) and SW velocities after MVC. In the multivariate model, SW velocities remained as the strongest predictor for peak VO2, followed by LVEDD, BMI and SBP (Figure 1). Moreover, natural SWs correlate significantly with both peak VO2 and VO2/work slope (r= -0.65; p <0.001, and r=-0.31; p =0.002 respectively) (Figure 2A&B). Interestingly, SW velocities were on average significantly higher in survivors with reduced peak VO2 (non-fit survivors) compared to both survivors with normal peak VO2 (fit survivors) and HV (4.2 ±0.6 m/s vs 3.5 ±0.5 m/s & 3.2 ±0.3 m/s respectively; p <0.001) (Figure 2C). Conclusions Our preliminary data indicate that natural SW velocities measured at rest are related to cardiorespiratory fitness and can identify hidden cardiac dysfunction among childhood cancer survivors. Natural SW elastography appears as promising and innovative echocardiographic parameter for early detection of cardiac dysfunction in follow-up of adult survivors of childhood cancer. Figure 1 Figure 2

The role of CPET in patients with reduced physical capacity and Hodgkin's disease at clinical remission

Hodgkin's lymphoma is a systemic disease of the lymphatic tissue that most commonly affects adolescents and young adults. Modern treatment of the disease aims at long-term remission in patients. During this process, some patients develop complications that require timely diagnosis and treatment. It is fundamental to ensure continuity between pediatric oncologists, pulmonologists, and cardiologists, pediatricians on the one hand, and specialists in the relevant field treating adult patients. Keeping and maintaining accurate patient medical data serves as a springboard for screening adolescents and young adults in remission after treatment for Hodgkin's lymphoma. The treatment methods (radiation, chemotherapy, etc.) have different mechanisms of action on the disease and, accordingly, different potential early and late complications. The role of functional breathing studies and cardiopulmonary stress tests with exercise in this group of patients can explain the etiology of clinical complaints, assess the functional status and effect of treatment, as well as timely diagnosis of complications during the treatment process with the aim of early cardio rehabilitation and achieving durable clinical remission.

Abstract 4146301: Relationship Between Calf Muscle Pump Function and Exercise Stress Testing

Background: Exercise stress testing uses metabolic equivalents of tasks (METs) to measure the energy cost of activities, aiding in the assessment of exercise capacity and cardiovascular health. Despite its significance, the correlation between calf muscle pump function (CPF) and exercise stress testing remains unexplored. We aimed to evaluate the relationship between CPF and peak METs as determined by cardiopulmonary treadmill exercise stress testing. Methods: The study included adults who underwent exercise cardiopulmonary stress testing and venous plethysmography at Mayo Clinic between April 2017 and March 2020. The protocols other than Bruce, Mayo, Modified Naughton, and Naughton protocols were excluded. The CPF ejection fraction (EF) was calculated per leg based on refill volumes post-exercise as a percentage of passive drain refill. The classification of CEAP (Clinical-Etiology-Anatomy-Pathophysiology) was utilized to better understand chronic venous insufficiency (CVI). Results: A total of 155 patients who underwent both exercise stress testing and venous plethysmography were included, with a mean age of 61.31 ± 14.03 years, and 84 (54.2%) were male. The peak measured METs for normal, unilaterally reduced, and bilaterally reduced CPF were 8.5 (2.5), 7.3 (2.1), and 7.1 (2.4), respectively (p=0.004, Figure 1). Multiple linear regression models were developed with METs as the outcome to determine if CPF was an independent predictor of METs on cardiopulmonary exercise stress testing. IIn model 1, the following independent variables were included: resting heart rate, peak heart rate, peak systolic blood pressure, recovery heart rate at minute 1, and worst EF (Table 1). In model 1, with only exercise parameters, lower EF was associated with lower METs (p=0.03). In a second analysis, variables identified as statistically significant with METs in the initial model were included, along with CEAP class (model 2) and CCI (model 3) (Table 2). In model 2, CEAP class 3 or higher was associated with decreased METs on the exercise stress test. This correlation implies that individuals with moderate to severe CVI may influence exercise capacity, demonstrating the interconnectedness of the cardiovascular system. Moreover, in model 3, the CCI, a predictor for mortality, was not significantly associated with METs. Conclusion: Our findings revealed that more severe CVI (CEAP class and reduced CPF) was associated with reduced exercise capacity after accounting for other factors.

Abstract 4132657: Age-related Differences in Peak Oxygen Uptake in Patients with Multimorbidity Undergoing Cardiac Rehabilitation

Background: Cardiac rehabilitation (CR) patients demonstrate a high burden of chronic conditions (CC). Both multimorbidity (MM; ≥2 coexisting CC) and aging negatively impact functional capacity, whereas CR improves performance. Age-related difference in cardiorespiratory fitness (CRF, peak oxygen uptake (VO 2 )) in CR patients with MM has not been studied. Hypothesis: We hypothesized improvement in CRF will be attenuated by MM with increasing age in CR patients. Aims: We aimed to identify age-related differences in CRF improvement in CR patients with MM. Methods: Patients ≥18 yrs old who attended ≥1 CR sessions from 1999-2017 and completed cardiopulmonary exercise stress test before and after CR were included. The prevalence of CC was assessed using Rochester Epidemiology Project records-linkage system. Age categories included: Younger (18-49 yrs), Midlife (50-64 yrs) and Older (≥65 yrs). CRF categories included: <0%, 0-8% and >8%. Analysis included Kruskal-Wallis and Chi-squared. Results: Of 622 patients, 75.4% were male. Mean age: 62.9±11.2 yrs; Younger (n=70) age: 42.7±6.8 yrs, 67.1% male; Midlife (n=283) age: 58.3±4.3 yrs, 78.8% male; Older (n=269) age: 73.0±5.2 yrs, 74.0% male. BMI was 29.9±5.4 kg/m 2 (Younger: 30.0±6.7, Midlife: 30.4±5.6, Older: 29.3±4.7; p<.05). Median (Q1, Q3) no. of CR sessions attended was 33(22, 35), with lower attendance in the Younger group: 25(16,34) vs Midlife: 33(20,35) and Older: 34 (29,35), p<.05. Overall, percent change in peak VO 2 was 11.5±21.6% (Younger: 18.8±22.8%, Midlife: 11.6±19.5%, Older: 9.4±23.1%; p<.01). The median number of CC was 7(5,8) with significant differences across groups: Younger: 5(3,7), Midlife: 6(5,8), Older: 7(6,9), p<.01. Number of CC increased with age across all CRF categories (p<.01, Fig. 1). However, there was no difference in number of CC within age groups across categories of CRF, Table 1. Conclusions: Our results suggest that MM increases with age in patients attending CR; however, within a given age group, improvement in CRF does not appear dependent on MM. The impact of age appears to have a greater impact than MM on CRF improvement. Individualized treatment plans should focus on the impact of age-related disparities on CRF improvement among CR patients with MM.

From the armchair to contemporary cardiac rehabilitation: the remarkable ongoing journey of exercise training in ischemic heart disease.

Exercise is an important physiological activity with several health benefits. In the setting of ischemic heart disease (IHD), the view toward exercise has greatly evolved throughout the years, concurrently to several major advances in the management of this complex entity. Currently, exercise training has broad applications across the IHD continuum as a powerful tool in its overall management, being a core component of comprehensive cardiac rehabilitation programs. Beyond this, exercise has also been incorporated as an integral part of contemporary methodologies aiming to provide diagnostic and prognostic data, such as cardiopulmonary exercise stress testing or stress echocardiography. In this article, we provide a pragmatic overview concerning the role of exercise in IHD, with a focus on its incorporation in cardiac rehabilitation frameworks, while also discussing some of the challenges and unmet needs concerning these interventions.

Artificial Intelligence and Its Role in Diagnosing Heart Failure: A Narrative Review.

Heart failure (HF) is prevalent globally. It is a dynamic disease with varying definitions and classifications due to multiple pathophysiologies and etiologies. The diagnosis, clinical staging, and treatment of HF become complex and subjective, impacting patient prognosis and mortality. Technological advancements, like artificial intelligence (AI), have been significant roleplays in medicine and are increasingly used in cardiovascular medicine to transform drug discovery, clinical care, risk prediction, diagnosis, and treatment. Medical and surgical interventions specific to HF patients rely significantly on early identification of HF. Hospitalization and treatment costs for HF are high, with readmissions increasing the burden. AI can help improve diagnostic accuracy by recognizing patterns and using them in multiple areas of HF management. AIhas shown promise in offering early detection and precise diagnoses with the help of ECG analysis, advanced cardiac imaging, leveraging biomarkers, and cardiopulmonary stress testing. However, its challenges include data access, model interpretability, ethical concerns, and generalizability across diverse populations. Despite these ongoing efforts to refine AI models, it suggests a promising future for HF diagnosis. After applying exclusion and inclusion criteria, we searched for data available on PubMed, Google Scholar, and the Cochrane Library and found 150 relevant papers. This review focuses on AI's significant contribution to HF diagnosis in recent years, drastically altering HF treatment and outcomes.

Possibilities of Predicting Peak Oxygen Consumption in Patients With Chronic Heart Failure According to the 6‑Minute Walk Test

To determine the correlation between the results of the 6-minute walk test (6MWT) and peak oxygen consumption (VO2peak) for populations of patients with chronic heart failure with pronounced clinical and demographic differences; to study a possibility of indirect measurement of VO2peak based on the results of 6MWT using the formulas available from the literature. Two databases were analyzed: 50 patients included in the AEROFIT study (group A), and 31 patients from the Almazov National Medical Research Center (group B). The inclusion criteria were the availability of data from the cardiopulmonary stress test and the 6MWT. The possibility of predicting VO2peak was calculated based on the results of 6MWT using the formulas reported in the literature (L. P. Cahalin et al., 1996; R. M. Ross et al., 2010; R. A. Adedoyin et al., 2010). The predictive accuracy of the models was assessed using the coefficient of determination (R2). The relationship between functional and clinical-demographic indicators was assessed using the Pearson or Spearman correlation analysis. The study groups differed significantly in all parameters, except for the proportion of men and the mean VO2peak. Group B patients were 20 years younger than group A patients, had a lower left ventricular ejection fraction (24.06±7.75 and 41.52±10.48 %, respectively; p<0.001), and covered a 130 m shorter distance in the 6MWT. Despite the absence of a significant difference in VO2peak between groups A and B (13.6 and 13.1 ml / kg / min, respectively; p=0.6581), 61 % of group B patients and 20% of group A belonged to Weber functional class IV. In group A, the 6MWT distance correlated closely with VO2peak (R=0.78; p<0.01) and weakly with age (R=0.4) and body mass index (R=0.3). In group B, the 6MWT distance correlated only with VO2peak (R=0.77; p<0.01). For group A, the R.M. Ross et al. model demonstrated high accuracy in determining the mean VO2peak value with a 0.06% prediction error normalized to measured VO2peak. For group B, none of the models showed satisfactory predictive accuracy. The Ross and Cahalin models showed the best coefficients of determination for groups A and B: Group A, Ross et al. (R2=0.58) and Cahalin et al. (R2=0.59); Group B, Ross et al. (R2=0.59) and Cahalin et al. (R2=0.6). In two groups of patients with a statistically insignificant difference in the mean values of VO2peak, the mean values of 6MWT distance were significantly different, although these indicators correlated closely. The VO2peak prediction models showed satisfactory accuracy for estimation of mean VO2, but poor accuracy for estimation of individual values. A better predictive accuracy is determined by similar clinical and demographic characteristics between the training and testing populations, and likely also by models based on larger, more diversified populations.

Detection of early heart failure with preserved ejection fraction in metabolic syndrome patients detected as part of a national screening program in middle aged subjects

Background: We wished to investigate if community detected Metabolic Syndrome (MetS) is associated with the burden of incipient heart failure with preserved ejection fraction (HFpEF) in the community. Methods and Results: We prospectively studied 148 consecutive MetS patients identified from the Lithuanian High Cardiovascular Risk primary prevention program and investigated them further for unknown HFpEF through cardiopulmonary stress testing as well as assessment of brain natriuretic peptide (BNP) levels and of arterial stiffness. Subjects with a peak oxygen consumption value lower than 90% of predicted and/or BNP≥35 ng/L were categorized as having early phase HFpEF. For comparison of this early phase HFpEF with others already clinically diagnosed with HFpEF, patients with both established HFpEF and MetS were selected retrospectively from patients attending our cardiopulmonary stress testing laboratory (n=38). Two thirds of the screening program derived MetS population (n=96) demonstrated a reduced exercise capacity and/or an elevated BNP, indicating signs of early HFpEF. Both the clinically diagnosed HFpEF and the screening program detected MetS group with early HFpEF demonstrated similarly decreased exercise tolerance evaluated by peak oxygen uptake (79.8±22.1% vs 82.7±14.0%, p>0.05). Analysis of arterial markers in the screening program group revealed statistically significant differences of augmentation index values between groups with and without signs of early HFpEF (p=0.016).Conclusions: A considerable proportion of patients having MetS may be diagnosed with previously undetected early stage HFpEF. The use of objective parameters of exercise capacity and neurohormonal activation might be effectively used for the early detection of HFpEF. Also, early HFpEF in this setting is found to be associated with increased arterial stiffness.

Detection of early heart failure with preserved ejection fraction in metabolic syndrome patients detected as part of a national screening program in middle aged subjects

Background: We wished to investigate if community detected Metabolic Syndrome (MetS) is associated with the burden of incipient heart failure with preserved ejection fraction (HFpEF) in the community. Methods and Results: We prospectively studied 148 consecutive MetS patients identified from the Lithuanian High Cardiovascular Risk primary prevention program and investigated them further for unknown HFpEF through cardiopulmonary stress testing as well as assessment of brain natriuretic peptide (BNP) levels and of arterial stiffness. Subjects with a peak oxygen consumption value lower than 90% of predicted and/or BNP≥35 ng/L were categorized as having early phase HFpEF. For comparison of this early phase HFpEF with others already clinically diagnosed with HFpEF, patients with both established HFpEF and MetS were selected retrospectively from patients attending our cardiopulmonary stress testing laboratory (n=38). Two thirds of the screening program derived MetS population (n=96) demonstrated a reduced exercise capacity and/or an elevated BNP, indicating signs of early HFpEF. Both the clinically diagnosed HFpEF and the screening program detected MetS group with early HFpEF demonstrated similarly decreased exercise tolerance evaluated by peak oxygen uptake (79.8±22.1% vs 82.7±14.0%, p>0.05). Analysis of arterial markers in the screening program group revealed statistically significant differences of augmentation index values between groups with and without signs of early HFpEF (p=0.016).Conclusions: A considerable proportion of patients having MetS may be diagnosed with previously undetected early stage HFpEF. The use of objective parameters of exercise capacity and neurohormonal activation might be effectively used for the early detection of HFpEF. Also, early HFpEF in this setting is found to be associated with increased arterial stiffness.

Detection of early heart failure with preserved ejection fraction in metabolic syndrome patients detected as part of a national screening program in middle aged subjects

Background: We wished to investigate if community detected Metabolic Syndrome (MetS) is associated with the burden of incipient heart failure with preserved ejection fraction (HFpEF) in the community. Methods and Results: We prospectively studied 148 consecutive MetS patients identified from the Lithuanian High Cardiovascular Risk primary prevention program and investigated them further for unknown HFpEF through cardiopulmonary stress testing as well as assessment of brain natriuretic peptide (BNP) levels and of arterial stiffness. Subjects with a peak oxygen consumption value lower than 90% of predicted and/or BNP≥35 ng/L were categorized as having early phase HFpEF. For comparison of this early phase HFpEF with others already clinically diagnosed with HFpEF, patients with both established HFpEF and MetS were selected retrospectively from patients attending our cardiopulmonary stress testing laboratory (n=38). Two thirds of the screening program derived MetS population (n=96) demonstrated a reduced exercise capacity and/or an elevated BNP, indicating signs of early HFpEF. Both the clinically diagnosed HFpEF and the screening program detected MetS group with early HFpEF demonstrated similarly decreased exercise tolerance evaluated by peak oxygen uptake (79.8±22.1% vs 82.7±14.0%, p>0.05). Analysis of arterial markers in the screening program group revealed statistically significant differences of augmentation index values between groups with and without signs of early HFpEF (p=0.016).Conclusions: A considerable proportion of patients having MetS may be diagnosed with previously undetected early stage HFpEF. The use of objective parameters of exercise capacity and neurohormonal activation might be effectively used for the early detection of HFpEF. Also, early HFpEF in this setting is found to be associated with increased arterial stiffness.

The Early Detection of Pulmonary Hypertension.

Up to 1% of the world population and 10% of all persons over age 65 suffer from pulmonary hypertension (PH). The latency from the first symptom to the diagnosis is more than one year on average, and more than three years in 20% of patients. 40% seek help from more than four different physicians until their condition is finally diagnosed. This review is based on publications retrieved by a selective literature search on pulmonary hypertension. The most common causes of pulmonary hypertension are left heart diseases and lung diseases. Its cardinal symptom is exertional dyspnea that worsens as the disease progresses. Additional symptoms of right heart failure are seen in advanced stages. Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are rare, difficult to diagnose, and of particular clinical relevance because specific treatments are available. For this reason, strategies for the early detection of PAH and CTEPH have been developed. The clinical suspicion of PH arises in a patient who has nonspecific symptoms, electrocardiographic changes, and an abnormal (NT-pro-)BNP concentration. Once the suspicion of PH has been confirmed by echocardiography and, if necessary, differential-diagnostic evaluation with a cardiopulmonary stress test, and after the exclusion of a primary left heart disease or lung disease, the patient should be referred to a PH center for further diagnostic assessment, classification, and treatment. If both the (NT-pro-)BNP and the ECG are normal, PH is unlikely. Knowledge of the characteristic clinical manifestations and test results of PH is needed so that patients can be properly selected for referral to specialists and experts in PH.

HeartWare Left Ventricular Assist Device Exercise Hemodynamics With Speed Adjustment Based on Left Ventricular Filling Pressures.

Functional capacity remains limited in heart failure patients with left ventricular assist devices (LVADs) due to fixed pump speed and inability to offload the left ventricle adequately. We hypothesized that manually adjusting LVAD speed during exercise based on pulmonary capillary wedge pressures would increase total cardiac output and maximal oxygen consumption. Two participants with a HeartWare LVAD underwent an invasive ramp study at rest followed by an invasive cardiopulmonary stress test exercising in two randomized phases: fixed speed and adjusted speed. In the latter phase, speed was adjusted every 1 minute during exercise at ±20 rpm/1 mm Hg change from baseline pulmonary capillary wedge pressure. There was no difference in maximal oxygen consumption between the two phases, with a modest increase in total cardiac output during speed adjustment. Filling pressures were initially controlled during speed adjustment until speed was capped at 4,000 rpm, at which point filling pressures increased. Blood pressure was variable. The pressure across the head of the pump (ΔP) was higher with speed adjustment. Contrary to our hypothesis, LVAD speed adjustment during exercise did not improve total cardiac output and functional capacity. This variable response may be attributed to the native cardiac reserve and baroreceptor response; however, additional studies are needed.

Agreement between two independent raters in identifying exercise oscillatory ventilation in patients with heart failure

Abstract Background Heart failure (HF) leads to several functional and ventilatory limitations, including exercise oscillatory ventilation (EOV), whose presence is associated with an adverse prognosis, with a risk more than 4 times higher for a cardiovascular event. Methods to identify the presence of EOV were created and are being reformulated based on the amplitude and duration in the oscillation of the ventilatory cycles. Despite the documented association between EOV and prognosis in HF, the diversity of methods and subjective interpretation can compromise the diagnosis and adequate risk stratification. Purpose To analyze the agreement of the EOV identification between two independent raters and compare the clinical characteristics of the patients with and without EOV. Methods A cross-sectional study was carried out using an electronic questionnaire containing graphs of exercise ventilation over time from treadmill cardiopulmonary stress tests (CPET) performed in patients with HF, with preserved or reduced left ventricular ejection fraction (LVEF). The graphs were interpreted by two cardiologists with extensive experience in performing CPET. The research was approved by the institution's ethics and research committee. Agreement was evaluated by Cohen Kappa statistics and the proportion of agreements between raters. Differences among variables according to the presence of EOV (identified by at least one of the raters) were analyzed with Mann-Whitney test. A two-sided p-value < 0.05 was considered significant for all analyses. Results The sample consisted of 31 patients (74% men, 56 years ± 10 years) with a LVEF of 44 ± 12%, 61% with reduced LVEF, 80% with NYHA functional classification I/II, and peak oxygen uptake (VO2peak) of 17.6 ± 4.3 mL/kg/min. The EOV identification by the raters revealed a moderate agreement, with Kappa of 0.56. The proportion of agreement was 84% (26 of 31 cases) and the specific agreement (presence of EOV) was 50% (5 of 10 cases) (Figure 1). Regarding the clinical characteristics of patients with and without EOV (Figure 2), the only variable with statistical difference was VO2peak, with lower values in the patients with EOV (14.9 versus 17.9 mL/kg/min; p = 0.019). Conclusion The agreement between two experienced raters was only moderate, which demonstrate that the identification of EOV remains challenging. The only clinical characteristics associated with presence of EOV in our sample was VO2peak, suggesting a poor prognosis in patients with HF and EOV.

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.

Hypotensive Response On Cardiopulmonary Stress Test Is Not Associated With Worse Post-heart Transplant Clinical Outcomes And Mortality

Hypotensive Response On Cardiopulmonary Stress Test Is Not Associated With Worse Post-heart Transplant Clinical Outcomes And Mortality

Cardiopulmonary Exercise Testing in Children and Young Adolescents after a Multisystem Inflammatory Syndrome: Physical Deconditioning or Residual Pathology?

Multisystem inflammatory syndrome in children (MIS-C) is a serious health condition that imposes a long-term follow-up. The purpose of our pilot study is to evaluate the usefulness of the cardiopulmonary stress test (CPET) in the follow-up after MIS-C. All patients admitted for MIS-C in our hospital in the 12 months preceding the date of observation were considered for inclusion in the study. Pre-existing cardio-respiratory diseases and/or the lack of collaboration were the exclusion criteria. At enrolment, each subject passed a cardiological examination, rest ECG, echocardiogram, 24 h Holter-ECG, blood tests, and a CPET complete of spirometry. A total of 20 patients met the inclusion criteria (11.76 ± 3.29 years, 13 male). In contrast to the normality of all second-level investigations, CPET showed lower-than-expected peakVO2 and peak-oxygen-pulse values (50% of cases) and higher-than-expected VE/VCO2-slope values (95% of cases). A statistically significant inverse correlation was observed between P-reactive-protein values at admission and peakVO2/kg values (p = 0.034), uric acid values at admission, and peakVO2 (p = 0.011) or peak-oxygen-pulse expressed as a percentage of predicted (p = 0.021), NT-proBNP values at admission and peakVO2 expressed as a percentage of predicted (p = 0.046). After MIS-C (4-12 months) relevant anomalies can be observed at CPET, which can be a valuable tool in the follow-up after this condition.

A drop in heart rate and cardiac output during cardiopulmonary stress testing in a patient with a dual chamber pacemaker.

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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.