Peak Circulatory Power Research Articles

The Interpretation of Standard Cardiopulmonary Exercise Test Indices of Cardiac Function in Chronic Kidney Disease

Background and Aims: As there is growing interest in the application of cardiopulmonary exercise test (CPX) in chronic kidney disease (CKD), it is important to understand the utility of conventional exercise test parameters in quantifying the cardiopulmonary fitness of patients with CKD. Merely extrapolating information from heart failure (HF) patients would not suffice. In the present study, we evaluated the utility of CPX parameters such as the peak O2-pulse and the estimated stroke volume (SV) in assessing the peak SV by comparing with the actual measured values. Furthermore, we compared the anaerobic threshold (AT), peak circulatory power, and ventilatory power with that of the measured values of the peak cardiac power (CPOpeak) in representing the cardiac functional reserve in CKD. We also performed such analyses in patients with HF for comparison. Method: A cross sectional study of 70 asymptomatic male CKD patients [CKD stages 2–5 (pre-dialysis)] without primary cardiac disease or diabetes mellitus and 25 HF patients. A specialized CPX with a CO2 rebreathing technique was utilized to measure the peak cardiac output and peak cardiac power output. The peak O2 consumption (VO2peak) and AT were also measured during the test. Parameters such as the O2-pulse, stroke volume, arteriovenous difference in O2 concentration [C(a-v)O2], peak circulatory power, and peak ventilatory power were all calculated. Pearson’s correlation, univariate, and multivariate analyses were applied. Results: Whereas there was a strong correlation between the peak O2-pulse and measured peak SV in HF, the correlation was less robust in CKD. Similarly, the correlation between the estimated SV and the measured SV was less robust in CKD compared to HF. The AT only showed a modest correlation with the CPOpeak in HF and only a weak correlation in CKD. A stronger correlation was demonstrated between the peak circulatory power and CPOpeak, and the ventilatory power and CPOpeak. In HF, the central cardiac factor was the predominant determinant of the standard CPX-derived surrogate indices of cardiac performance. By contrast, in CKD both central and peripheral factors played an equally important role, making such indices less reliable markers of cardiac performance per se in CKD. Conclusion: The results highlight that the standard CPX-derived surrogate markers of cardiac performance may be less reliable in CKD, and that further prospective studies comparing such surrogate markers with directly measured cardiac hemodynamics are required before adopting such markers into clinical practice or research in CKD.

Cardiopulmonary response to exercise in adults born very preterm.

This study aims to compare cardiopulmonary response to aerobic exercise between young adults born very preterm, including a subgroup with bronchopulmonary dysplasia (BPD), and term controls.Seventy-one adults (18-29 years) born <30 weeks' gestational age (24 with BPD) and 73 term controls were recruited. Assessment included cardiopulmonary exercise testing with impedance cardiography. We compared group differences in peak O2 consumption (peak VO2) and in ventilatory and cardiovascular responses to exercise using linear regression analyses.Preterm participants had reduced peak VO2 (mean difference -2.7; 95% CI -5.3, -0.1 mL·kg-1 lean body mass·min-1) versus controls. Those with BPD achieved lower peak work-rate compared to term controls (-21; 95% CI -38, -5 watts). There was no difference across groups in breathing reserve, ventilatory efficiency, peak heart rate and cardiac output. VO2 to work-rate relationship (ΔVO2/ΔWR) was reduced in preterm versus term. Peak systolic blood pressure and circulatory power (systolic blood pressure*VO2) were also lower in BPD versus term controls. In the preterm group, longer NICU stay and lower peak cardiac output were associated with lower peak VO2Results suggest limitations with peripheral O2 uptake in the muscle with reduced ΔVO2/ΔWR and peak circulatory power, but normal cardiac output. Investigations into skeletal muscle perfusion and O2 use during exercise are warranted to better understand mechanisms of exercise limitation.

Apelin as a Potential Regulator of Peak Athletic Performance

Apelin, as a cardiokine/myokine, is emerging as an important regulator of cardiac and skeletal muscle homeostasis. Loss of apelin signaling results in premature cardiac aging and sarcopenia. However, the contribution of apelin to peak athletic performance remains largely elusive. In this paper, we assessed the impact of maximal cardiorespiratory exercise testing on the plasma apelin levels of 58 male professional soccer players. Circulating apelin-13 and apelin-36, on average, increased transiently after a single bout of treadmill exercise; however, apelin responses (Δapelin = peak - baseline values) showed a striking interindividual variability. Baseline apelin-13 levels were inversely correlated with those of Δapelin-13 and Δapelin-36. Δapelin-13 showed a positive correlation with the maximal metabolic equivalent, relative maximal O2 consumption, and peak circulatory power, whereas such an association in the case of Δapelin-36 could not be detected. In conclusion, we observed a pronounced individual-to-individual variation in exercise-induced changes in the plasma levels of apelin-13 and apelin-36. Since changes in plasma apelin-13 levels correlated with the indicators of physical performance, whole-body oxygen consumption and pumping capability of the heart, apelin, as a novel exerkine, may be a determinant of peak athletic performance.

Effects of Mavacamten on Measures of Cardiopulmonary Exercise Testing Beyond Peak Oxygen Consumption

Mavacamten, a cardiac myosin inhibitor, improved peak oxygen uptake (pVO2) in patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM) in the EXPLORER-HCM study. However, the full extent of mavacamten's effects on exercise performance remains unclear. To investigate the effect of mavacamten on exercise physiology using cardiopulmonary exercise testing (CPET). Exploratory analyses of the data from the EXPLORER-HCM study, a randomized, double-blind, placebo-controlled, phase 3 trial that was conducted in 68 cardiovascular centers in 13 countries. In total, 251 patients with symptomatic obstructive HCM were enrolled. Patients were randomly assigned in a 1:1 ratio to mavacamten or placebo. The following prespecified exploratory cardiovascular and performance parameters were assessed with a standardized treadmill or bicycle ergometer test protocol at baseline and week 30: carbon dioxide output (VCO2), minute ventilation (VE), peak VE/VCO2 ratio, ventilatory efficiency (VE/VCO2 slope), peak respiratory exchange ratio (RER), peak circulatory power, ventilatory power, ventilatory threshold, peak metabolic equivalents (METs), peak exercise time, partial pressure of end-tidal carbon dioxide (PETCO2), and VO2/workload slope. Two hundred fifty-one patients were enrolled. The mean (SD) age was 58.5 (11.9) years and 59% of patients were male. There were significant improvements with mavacamten vs placebo in the following peak-exercise CPET parameters: peak VE/VCO2 ratio (least squares [LS] mean difference, -2.2; 95% CI, -3.05 to -1.26; P < .001), peak METs (LS mean difference, 0.4; 95% CI, 0.17-0.60; P < .001), peak circulatory power (LS mean difference, 372.9 mL/kg/min × mm Hg; 95% CI, 153.12-592.61; P = .001), and peak PETCO2 (LS mean difference, 2.0 mm Hg; 95% CI, 1.12-2.79; P < .001). Mavacamten also improved peak exercise time compared with placebo (LS mean difference, 0.7 minutes; 95% CI, 0.13-1.24; P = .02). There was a significant improvement in nonpeak-exercise CPET parameters, such as VE/VCO2 slope (LS mean difference, -2.6; 95% CI, -3.58 to -1.52; P < .001) and ventilatory power (LS mean difference, 0.6 mm Hg; 95% CI, 0.29-0.90; P < .001) favoring mavacamten vs placebo. Mavacamten improved a range of CPET parameters beyond pVO2, indicating consistent and broad benefits on maximal exercise capacity. Although improvements in peak-exercise CPET parameters are clinically meaningful, the favorable effects of mavacamten on submaximal exertional tolerance provide further insights into the beneficial impact of mavacamten in patients with obstructive HCM. ClinicalTrials.gov Identifier: NCT03470545.

Value of cardiopulmonary exercise test submaximal parameters in the assessment of aortic stenosis patients

Abstract Background Exercise test is recommended for risk stratification of asymptomatic patients with severe aortic stenosis (AS), although a significant number of patients can't perform a maximal exercise test, increasing the potential value of sub-maximal parameters for the assessment of these patients. Aim To assess which parameters could be useful for risk stratification in case of a submaximal Cardiopulmonary Exercise Testing (CPET) in asymptomatic patients with severe AS. Methods Retrospective evaluation of adult patients with asymptomatic severe AS, in a single center, who underwent CPET between December 2016 and November 2021. All patients underwent a treadmill CPET using an exercise protocol with progressive increase in workload. Patients were divided in group A (maximal CPET) or group B, respectively, if respiratory exchange ratio (RER) was &amp;gt;1.10 at peak exercise or below this value. Known parameters accessed in a submaximal CPET were evaluated: mean minute ventilation/carbon dioxide production slope (VE/VCO2), VO2 value in first ventilatory threshold (VT1), peak circulatory power, and oxygen uptake efficiency slope (OUES). Results CPET was performed in 25 patients with severe asymptomatic AS (80 years ± 7 years, 56% male), median AVA was 0.86 cm2 [IQR 0.65–0.95 cm2] and transaortic pressure gradient was 46 mmHg [IQR 41–55 mmHg]. The most used protocol was a ramp slope. Nineteen patients (76%) didn't reach a RER&amp;gt;1.10 (group B) due to respiratory (26%) or peripheral limitation (53%). Comparing both groups, group B patients showed a shorter duration of exercise of (8±3 min vs. 9±4 min, p=0.422), and a lowest mean peak VO2 (16.3±3.6 vs. 20.5±6.9 ml/kg/min, p=0.207). In our population, bivariate analyses demonstrated that OUES was the only submaximal parameter that could discriminate both groups: Group B patients had the lowest values (1.53 [IQR 1.47–1.70] vs. 1.94 [IQR 1.56–2.11], p=0.042). ROC curve analysis of OUES values revealed an AUC of 0.78 (p=0.042) for maximal CPET prediction. The cut-off point with most sensitivity (S) and specificity (E) obtained using the Youden index (0.62) was 1.9 (S≈67%; E≈95%) (Figure 1). Conclusions In our cohort of asymptomatic AS patients, even with submaximal CPET, OUES accurately identify patients with higher degrees of functional limitation. Whether OUES is useful as prognostic marker to the workflow treatment of AS it's worth to be assessed prospectively. Funding Acknowledgement Type of funding sources: None.

Peak Circulatory Power during Maximal Cardiopulmonary Exercise Testing: Reference Standards from the FRIEND Registry.

Normative standards for key cardiopulmonary exercise (CPX) test variables, including peak circulatory power (CircP), are needed to guide the interpretation of clinical exercise responses in individuals with and without disease. This study aimed to establish age- and sex-specific reference standards for peak CircP derived from a healthy cohort from the Fitness Registry and the Importance of Exercise: A National Database (FRIEND). CPX test data from apparently healthy males and females from eight FRIEND United States exercise laboratories were considered. Inclusion criteria included ages 20-79 yr and a maximal, symptom-limited exercise test performed on a treadmill or cycle ergometer. CircP was calculated as the product of peak oxygen consumption and peak systolic blood pressure. Reference values were determined on both treadmill and cycle ergometer for males and females per age decade. A stepwise linear regression to predict CircP was derived from two-thirds of the sample while the remaining one-third was used as a validation cohort. A total of 6736 CPX tests (47% treadmill, 53% female) were included in the analysis. Overall, CircP was higher in males, higher on tests conducted on a treadmill, and decreased with age. Sex, exercise mode, age, and body mass index were the most significant contributors to CircP (multiple R = 0.75, R2 = 0.57, root-mean-square error = 1200 mm Hg·mL O 2 ·kg -1 ·min -1 , P < 0.001). Using the generated prediction equation, the average percent-predicted CircP for the validation cohort was 101.3% ± 28.1%. These results establish reference standards for CircP, a potentially important prognostic indicator of cardiovascular health. Future research exploring the role of percentiles and percent-predicted values for CircP is necessary as they may provide additional prognostic insight.

Peak Circulatory Power Is A Strong Prognostic Factor In Heart Failure With Preserved Ejection Fraction

<h3>Objectives</h3> Cardiopulmonary exercise testing (CPET) is the gold standard for assessing functional capacity and estimating prognosis in chronic heart failure (CHF). Peak circulatory power (CP) defined as the product of peak oxygen uptake (VO₂ peak) and peak exercise systolic blood pressure (SBP) was originally introduced by Cohen-Solal et al (2002) and eventually evaluated as a prognostic index in systolic CHF, congenital heart disease and idiopathic pulmonary arterial hypertension. The aim of this study was to confirm prognostic value of peak CP in HF with preserved ejection fraction (HFpEF). <h3>Methods</h3> We retrospectively analyzed the subgroup of 50 patients with HFpEF, NYHA classes II-III (17 female, mean age 64,8±11,6 years) previously enrolled in the prospective observational study. All patients received optimal medical treatment. At baseline the patients underwent comprehensive investigation including CPET. Peak CP was assessed as the product of VO₂ peak and peak SBP. Average follow-up period amounted 35 months. Cardiovascular mortality was considered the primary end-point. <h3>Results</h3> Cardiovascular mortality amounted 32% (n=16). ROC-analysis demonstrated significant independent predictive value of peak CP for cardiovascular mortality (AUC=0,741; 95% CI=0,597 to 0,854; p=0,0025). According to Youden index (J = sensitivity + specificity - 1) the patients were subsequently dichotomized by peak CP of 1600 as a cut-off point (sensitivity = 56%, specificity=91%). Kaplan-Meier analysis confirmed unfavorable prognosis in patients with peak CP ≤ 1600 (Log rank chi square = 8,3; p = 0,004). <h3>Conclusion</h3> Peak circulatory power (CP) combining VO₂ peak and peak exercise systolic blood pressure demonstrates significant prognostic value in HFpEF. Low peak CP reflecting poor cardiac power indicates unfavorable prognosis in terms of cardiovascular mortality and may be used as an independent non-invasive marker for long-term risk stratification in HFpEF patients.

Prognostic Role Of Cardiopulmonary Exercise Testing In Wild Type Transthyretin Amyloid Cardiomyopathy Patients Treated With Tafamidis

<h3>Background</h3> Prognostic value of cardiopulmonary exercise test (CPET) in heart failure with reduced ejection fraction is well established, but it's utility in wild type transthyretin cardiac amyloidosis (wtATTR) patients treated with Tafamidis is unknown. <h3>Objective</h3> To determine the role of baseline CPET in Tafamidis treated wtATTR amyloid patients. <h3>Methods</h3> A retrospective study was conducted to identify wtATTR patients who were treated with Tafamidis and underwent baseline CPET at The University of Kansas Amyloid Clinic from 8/31/2018 until 3/31/2020. Univariate and multivariate logistic regression models were used to predict the occurrence of the primary outcome (composite of mortality, heart transplant, and palliative inotrope initiation). <h3>Results</h3> A total of 33 patients were included with a mean age of 81 ± 5.7 years. About 84% were Caucasians and 79% were males. Mean peak oxygen consumption (VO₂) and peak circulatory power (CP) were low at 11.88 ± 3.74 ml/kg/min and 1667.8 ± 804.2 mmHg/ml/min, respectively. Mean VE/VCO₂ (Ventilatory efficiency) was 36.65 ± 8.7. After 1 year follow-up, 11 patients had reached the primary outcome. Median exercise duration was significantly lower in patients with primary outcomes compared to those without as shown in figure 1 [4.4 (IQR 3.6-4.7) vs 6.9 (IQR 5.9-8.9), p <0.001]. Upon multivariate analysis; peak VO₂ [OR 0.25, CI(0.07-0.91), p=0.03], peak CP [OR 0.99,CI(0.98-0.99), p=0.03] and peak VO₂/HR (Oxygen pulse) [OR 0.44, CI(0.22-0.87), p=0.02] were significantly associated with the primary outcome. VE/VC0₂ (Ventilatory efficiency) was not significantly associated with the primary outcome. (Table 1) <h3>Conclusion</h3> Peak V02, peak CP, and peak VO₂/HR may have a prognostic role in selecting which wtATTR patients will benefit from Tafamidis treatment.

Three dimensional myocardial deformation parameters are associated with functional capacity in hypertrophic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Three-dimensional (3D) echocardiography is an emerging tool for assessment of left ventricular function, with a promising role in the evaluation of cardiomyopathies. Hypertrophic cardiomyopathy (HCM) is often associated with reduced exercise capacity. The aim of this study was to evaluate the importance of 3D myocardial deformation parameters as predictors of exercise capacity in HCM patients (P). Methods This prospective study enrolled P with HCM. Each P underwent a comprehensive transthoracic echocardiogram including 3D speckle-tracking to measure global longitudinal, radial and circumferential strain, twist, torsion and global area strain. Functional capacity was objectively assessed by treadmill cardiorespiratory exercise testing. Results 83 patients with HCM, 50 (60%) male, mean left ventricular ejection fraction (LVEF) of 68 ± 7%, 27 (33%) with obstructive HCM (LV outflow tract [LVOT] gradient of 89 ± 60 mmHg). Impairment in LV myocardial deformation parameters was significantly correlated with lower peak VO2: global longitudinal 3D strain (r=-0.397, p &amp;lt; 0.001), global radial 3D strain (r = 0.336, p = 0.003) and global circumferential 3D strain (r=-0.353, p = 0.002) (Figure 1). Impaired LV twist was significantly correlated with inferior peak VO2 (r = 0.264, p = 0.033) (Fig.2) and peak circulatory power (r = 0.371, p = 0.003). Torsion impairment also significantly associated with lower peak VO2 (r = 0.285, p = 0.021), circulatory power (r = 0.380, p = 0.002), time to ventilatory anaerobic threshold (VAT) (r = 0.369, p = 0.003) and (VE/VCO2 slope)/peak VO2 ratio (r=-0.316, p = 0.012). Furthermore, global area strain impairment showed significant relation with decreased peak VO2 (r=-0.368, p = 0.001), lower exercise duration (r=-0.384, p = 0.001), time to VAT (r=-0.404, p &amp;lt; 0.001), circulatory power (r=-0.272, p = 0.032) and (VE/VCO2 slope)/peak VO2 ratio (r = 0.391, p = 0.002). LV twist (r=-0.135, p = 0.284), torsion (r=-0.120, p = 0.341) and global area strain (r = 0.152, p = 0.235) impairment did not correlate with VE/VCO2 slope. Exercise capacity was not associated with LV mass index (r = 0.209, p = 0.095), LV end-diastolic volume (r = 0.058, p = 0.639), maximum wall thickness (r = 0.041, p = 0.744), LVEF (r=-0.092, p = 0.458), 2D global longitudinal strain (r=-0.024, p = 0.848) or peak LVOT gradient (r=-0.006, p = 0.964). In a subanalysis examining only the nonobstructive (nHCM) P, we found that peak VO2 had a superior correlation with global longitudinal 3D strain (r=-0.420, p = 0.004), global radial 3D strain (r = 0.356, p = 0.016) and global circumferential 3D strain (r=-0.357, p = 0.016) as well as LV twist (r = 0.300, p = 0.046) and torsion (r = 0.336, p = 0.024). Conclusion Although P with HCM often have supranormal LVEF, 3D speckle-tracking echocardiographic imaging has the potential to demonstrate subclinical impairment of LV function. Impaired LV 3D strain, twist, torsion and global area strain were associated with reduced exercise capacity, particularly in nHCM P. Abstract Figure. Peak VO2 and 3D strain parameters Abstract Figure. LV twist, torsion and global area strain

The impact of cardiopulmonary exercise-derived scoring on prediction of cardio-cerebral outcome in hypertrophic cardiomyopathy.

Sudden cardiac death (SCD) and stroke-related events accompanied by atrial fibrillation (AF) can affect morbidity and mortality in hypertrophic cardiomyopathy (HCM). This study sought to evaluate a scoring system predicting cardio-cerebral events in HCM patients using cardiopulmonary exercise testing (CPET). We investigated the role of a previous prediction model based on CPET, the HYPertrophic Exercise-derived Risk score for Heart Failure-related events (HyperHF), which is derived from peak circulatory power ventilatory efficiency and left atrial diameter (LAD), for predicting a composite of SCD-related (SCD, serious ventricular arrhythmia, death from cardiac cause, heart failure admission) and stroke-related (new-onset AF, acute stroke) events. The Novel HyperHF risk model using left atrial volume index (LAVI) instead of LAD was proposed and compared with the previous HCM Risk-SCD model. A total of 295 consecutive HCM patients (age 59.9±13.2, 71.2% male) who underwent CPET was included in the present study. During a median follow-up of 742 days (interquartile range 384-1047 days), 29 patients (9.8%) experienced an event (SCD-related event: 14 patients (4.7%); stroke-related event: 17 patients (5.8%)). The previous model for SCD risk score showed fair prediction ability (AUC of HCM Risk-SCD 0.670, p = 0.002; AUC of HyperHF 0.691, p = 0.001). However, the prediction power of Novel HyperHF showed the highest value among the models (AUC of Novel HyperHF 0.717, p<0.001). Both conventional HCM Risk-SCD score and CPET-derived HyperHF score were useful for prediction of overall risk of SCD-related and stroke-related events in HCM. Novel HyperHF score using LAVI could be utilized for a better prediction power.

Prognostic Role of Cardiopulmonary Exercise Testing in Wild-Type Transthyretin Amyloid Cardiomyopathy Patients Treated With Tafamidis

BackgroundThe prognostic value of cardiopulmonary exercise testing (CPET) in patients with wild-type transthyretin cardiac amyloidosis treated with tafamidis is unknown. Methods and ResultsThis retrospective study included patients with wtATTR who underwent baseline cardiopulmonary exercise testing and were treated with tafamidis from August 31, 2018, until March 31, 2020. Univariate logistic and multivariate cox-regression models were used to predict the occurrence of the primary outcome (composite of mortality, heart transplant, and palliative inotrope initiation). A total of 33 patients were included (median age 82 years, interquartile range [IQR] 79–84 years), 84% were Caucasians and 79% were males). Majority of patients had New York Heart Association functional class III disease at baseline (67%). The baseline median peak oxygen consumption (VO2) and peak circulatory power (CP) were 11.35 mL/kg/min (IQR 8.5–14.2 mL/kg/min) and 1485.8 mm Hg/mL/min (IQR 988–2184 mm Hg/mL/min), respectively, the median ventilatory efficiency was 35.7 (IQR 31–41.2). After 1 year of follow-up, 11 patients experienced a primary end point. Upon multivariate analysis, the low peak VO2 (hazard ratio [HR] 0.43, 95% confidence interval [CI] 0.23–0.79, P = .007], peak CP (HR 0.98, 95% CI 0.98–0.99, P = .02), peak oxygen pulse (HR 0.62, 95% CI 0.39–0.97, P = .03), and exercise duration of less than 5.5 minutes (HR 5.82, 95% CI 1.29–26.2, P = .02) were significantly associated with the primary outcome. ConclusionsTafamidis-treated patients with wtATTR who had baseline low peak VO2, peak CP, peak O2 pulse, and exercise duration of less than 5.5 minutes had worse outcomes.

Quantifying the relationship and contribution of mitochondrial respiration to systemic exercise limitation in heart failure.

AimsHeart failure with reduced ejection fraction (HFrEF) induces skeletal muscle mitochondrial abnormalities that contribute to exercise limitation; however, specific mitochondrial therapeutic targets remain poorly established. This study quantified the relationship and contribution of distinct mitochondrial respiratory states to prognostic whole‐body measures of exercise limitation in HFrEF.Methods and resultsMale patients with HFrEF (n = 22) were prospectively enrolled and underwent ramp‐incremental cycle ergometry cardiopulmonary exercise testing to determine exercise variables including peak pulmonary oxygen uptake (V̇O2peak), lactate threshold (V̇O2LT), the ventilatory equivalent for carbon dioxide (V̇E/V̇CO2LT), peak circulatory power (CircPpeak), and peak oxygen pulse. Pectoralis major was biopsied for assessment of in situ mitochondrial respiration. All mitochondrial states including complexes I, II, and IV and electron transport system (ETS) capacity correlated with V̇O2peak (r = 0.40–0.64; P < 0.05), V̇O2LT (r = 0.52–0.72; P < 0.05), and CircPpeak (r = 0.42–0.60; P < 0.05). Multiple regression analysis revealed that combining age, haemoglobin, and left ventricular ejection fraction with ETS capacity could explain 52% of the variability in V̇O2peak and 80% of the variability in V̇O2LT, respectively, with ETS capacity (P = 0.04) and complex I (P = 0.01) the only significant contributors in the model.ConclusionsMitochondrial respiratory states from skeletal muscle biopsies of patients with HFrEF were independently correlated to established non‐invasive prognostic cycle ergometry cardiopulmonary exercise testing indices including V̇O2peak, V̇O2LT, and CircPpeak. When combined with baseline patient characteristics, over 50% of the variability in V̇O2peak could be explained by the mitochondrial ETS capacity. These data provide optimized mitochondrial targets that may attenuate exercise limitations in HFrEF.

Cardiac rehabilitation in elderly myocardial infarction survivors: focus on circulatory power.

Exercise-based cardiac rehabilitation (EBCR) is paramount after an acute myocardial infarction (AMI). Older individuals have been reported as having a worse prognosis after an AMI, and some series have reported differences in the functional response to EBCR. The peak circulatory power (CP), a non-invasive parameter, has been described as a surrogate for the cardiac power, showing promising results as a comprehensive measure of the cardiovascular response. Whilst this, data concerning the impact of EBCR on CP, particularly among elderly individuals, remains elusive. To address this issue, an observational, retrospective study including all patients admitted due to an AMI who completed a phase II EBCR programme between 11/2012 and 4/2017, was conducted, with CP being analysed by a symptom-limited cardiopulmonary exercise test. A total of 379 patients, 30% aged ≥65 years-old, were included. CP significantly improved after the EBCR programme (in all patients, as well as in both subgroups). Older patients presented lower CP than their younger counterparts at the beginning and the end of the programme, while presenting smaller improvements (122 ± 540 vs 293 ± 638 mmHg mL/kg/min, p = 0.013). This was maintained after adjusting for several potential confounding factors. A contemporary ECBR programme was associated with significant improvements in CP among AMI patients. Though those aged ≥65 years-old presented smaller improvements in CP than younger individuals, these still presented significant increases in this parameter. These results highlight the importance of EBCR in this challenging higher risk group of patients.

Reduction of functional cardiovascular reserve in the stages of chronic kidney disease.

Patients with chronic kidney disease (CKD) present reduced oxygen consumption at peak exercise (VO2 peak). No studies have evaluated objective measures of the cardiovascular reserve, besides VO2 peak and VO2 at the anaerobic threshold (VO2 AT), and compared these measures among ckd patients at different stages of the disease. Fifty-eight patients [pre-dialysis group (PD)=26, hemodialysis group (HD)=20, and post-kidney transplant group (KT)=12] were included. The following measures of cardiovascular reserve were obtained: 1) peak heart rate (HR); 2) peak systolic blood pressure (SBP); 3) VO2 peak and % predicted; 4) VO2 AT and % of predicted VO2; 5) peak circulatory power; 6) ventilatory efficiency for the production of carbon dioxide (VE/VCO2 slope); 7) oxygen uptake efficiency slope (OUES); and 8) recovery of gas exchange. The VO2 peak and VO2 AT in the PD, HD, and KT groups were reduced to 86% and 69%, 70% and 57%, and 79% and 64% of the predicted value, respectively. Patients in the HD group had lower VO2 peak (17.5±5.9 vs. 23.2±8.2 [p-value=0.036]) and VO2 AT (14.0±5.2 vs. 18.3±4.7 [p-value=0.039]) compared to patients in the KT group. OUES was significantly lower in the HD group compared to the KT group (p-value=0.034). Age in the PD, HD, and KT groups and sedentary lifestyle in the KT group were predictors of VO2 peak. CKD patients presented a reduction in cardiovascular reserve regardless of the stage of the disease. However, hemodialysis patients presented a greater reduction of cardiovascular reserve when compared to post-kidney transplant patients.

Cardiac rehabilitation after acute coronary syndrome: Do all patients derive the same benefit?

IntroductionCardiac rehabilitation (CR) has been demonstrated to improve exercise capacity in acute coronary syndrome (ACS), but not all patients derive the same benefit. Careful patient selection is crucial to maximize resources. ObjectiveTo identify in a heterogeneous ACS population which patients would benefit the most with CR, in terms of functional capacity (FC), by using cardiopulmonary exercise testing (CPET). MethodsA retrospective analysis of consecutive ACS patients who underwent CR and CPET was undertaken. CPET was performed at baseline and after 36 sessions of exercise. Peak oxygen uptake (pVO2), percentage of predicted pVO2, minute ventilation/CO2 production (VE/VCO2) slope, VE/VCO2 slope/pVO2 and peak circulatory power (PCP) (pVO2 times peak systolic blood pressure) were assessed in two moments. The differences in pVO2 (ΔpVO2), %pVO2, PCP and exercise test duration were calculated. Patients were classified according to baseline pVO2 (group 1, <20 ml/kg/min vs. group 2, ≥20 ml/kg/min) and left ventricular ejection fraction (group A, <50% vs. group B, ≥50%). ResultsWe analyzed 129 patients, 86% male, mean age 56.3±9.8 years. Both group 1 (n=31) and group 2 (n=98) showed significant improvement in FC after CR, with a more significant increase in pVO2, in group 1 (ΔpVO2 4.4±7.3 vs. 1.6±5.4; p=0.018). Significant improvement was observed in CPET parameters in group A (n=34) and group B (n=95), particularly in pVO2 and test duration. ConclusionPatients with lower baseline pVO2 (<20 ml/kg/min) presented more significant improvement in FC after CR. CPET which is not routinely used in assessement before CR in context of ACS, could be a valuable tool to identify patients who will benefit the most.

Cardiac rehabilitation after acute coronary syndrome: Do all patients derive the same benefit?

IntroductionCardiac rehabilitation (CR) has been demonstrated to improve exercise capacity in acute coronary syndrome (ACS), but not all patients derive the same benefit. Careful patient selection is crucial to maximize resources. ObjectiveTo identify in a heterogeneous ACS population which patients would benefit the most with CR, in terms of functional capacity (FC), by using cardiopulmonary exercise testing (CPET). MethodsA retrospective analysis of consecutive ACS patients who underwent CR and CPET was undertaken. CPET was performed at baseline and after 36 sessions of exercise. Peak oxygen uptake (pVO2), percentage of predicted pVO2, minute ventilation/CO2 production (VE/VCO2) slope, VE/VCO2 slope/pVO2 and peak circulatory power (PCP) (pVO2 times peak systolic blood pressure) were assessed in two moments. The differences in pVO2 (ΔpVO2), %pVO2, PCP and exercise test duration were calculated. Patients were classified according to baseline pVO2 (group 1, <20 ml/kg/min vs. group 2, ≥20 ml/kg/min) and left ventricular ejection fraction (group A, <50% vs. group B, ≥50%). ResultsWe analyzed 129 patients, 86% male, mean age 56.3±9.8 years. Both group 1 (n=31) and group 2 (n=98) showed significant improvement in FC after CR, with a more significant increase in pVO2, in group 1 (ΔpVO2 4.4±7.3 vs. 1.6±5.4; p=0.018). Significant improvement was observed in CPET parameters in group A (n=34) and group B (n=95), particularly in pVO2 and test duration. ConclusionPatients with lower baseline pVO2 (<20 ml/kg/min) presented more significant improvement in FC after CR. CPET which is not routinely used in assessement before CR in context of ACS, could be a valuable tool to identify patients who will benefit the most.

Left ventricular diastolic performance at rest is essential for exercise capacity in patients with non-complicated myocardial infarction

IntroductionIn patients with recent myocardial infarction (MI) limited exercise capacity during physical activity is an important symptom and the base for future treatment. The myocardial injury after MI leads to both systolic and diastolic left ventricular (LV) dysfunction. ObjectiveThe aim of this study was to assess the relevance of systolic and diastolic LV function for cardiopulmonary exercise capacity in patients with prior MI. MethodsSixty-five consecutive patients after first MI without signs and symptoms of heart failure, aged 52 ± 6 years, were included in the study. The following echo parameters were evaluated: LV ejection fraction (LVEF), peak early and late diastolic velocities (E, A), deceleration time of E wave (dec t E), ratio of early trans-mitral to early annular diastolic velocities (E/e′), velocity propagation of early filling (Vp), and diameters and volumes of LV and left atrium (LA). CPET variables included: oxygen uptake at peak exercise (peak VO2), oxygen pulse (VO2 HR), VE/VCO2 slope, circulatory power (CP) and recovery half time (T1/2). ResultsSignificant correlations were demonstrated between peak VO2 and E/e’ (p < 0.001), peak VO2 and dec t E (p < 0.001), VO2 HR and E/e′ (p = 0.002) and between VE/VCO2 and E/e′ (p < 0.001). Twenty patients with elevated LV filling pressure achieved significantly lower peak VO2 (1624 vs. 1932 ml, p = 0.027) VO2 HR (11.70 vs. 14.05, p = 0.011) and CP (287,073 vs. 361,719, p = 0.014). By using multivariate regression model we found that only E/e′ (p = 0.001) and dec t E (p = 0.008) significantly contributed to peak VO2. ConclusionsDiastolic dysfunction, particularly LV filling pressure, determine exercise capacity, despite differences in LV ejection fraction in patients with prior MI.

Determinants of exercise peak arterial blood pressure, circulatory power, and exercise cardiac power in a population based sample of Finnish male and female aged 30 to 47 years: the Cardiovascular Risk in Young Finns Study

BackgroundNovel parameters derived from peak maximal oxygen uptake (VO2) and exercise arterial blood pressure, such as peak circulatory power (CP) and exercise cardiac power (ECP), can be used in the risk assessment of cardiovascular disease and stroke. However, the determinants of these factors are poorly characterized in the general population.MethodsWe assessed peak arterial blood pressure, CP and ECP with standardized cardiopulmonary exercise test (CPET) on 281 female and 257 male participants of the Cardiovascular Risk in Young Finns Study. The subjects were aged 30–47 years. Peak VO2 as well as systolic and diastolic arterial blood pressures were measured to calculate peak mean arterial pressure, CP and ECP. These parameters were assessed for correlation with sex, age, height, weight, waist-to-hip ratio, smoking, physical activity index (PAI), fasting insulin and glucose levels as well as the use of antihypertensive treatment.ResultsSex, age and weight explained 36% of the variation in peak systolic blood pressure, and these factors in combination with height and the use of antihypertensive treatment explained 13% of the variation in peak diastolic blood pressure. Sex, height, weight, waist-to-hip ratio, PAI and smoking explained 49% − 52% of the variation in peak CP. Sex, age, height, weight, waist-to-hip ratio, PAI, smoking and insulin levels explained 21% − 49% of variation in ECP.ConclusionsSubject demographics and lifestyle-related factors should be taken into account when exercise blood pressure response, CP and ECP are used to evaluate patients’ cardiac function in CPET.

Relationship between peak cardiac pumping capability and selected exercise‐derived prognostic indicators in patients treated with left ventricular assist devices

Exercise-derived variables have been used in the assessment of functional capacity and prognosis in patients with chronic heart failure. The aim of this study was to assess the relationship between cardiac pumping capability represented by peak cardiac power output and peak oxygen consumption, anaerobic threshold, ventilatory efficiency slope, and peak circulatory power in patients undergoing the 'Harefield Protocol'. Haemodynamic and gas exchange measurements were undertaken during a graded treadmill exercise test. They were performed on 54 patients-18 implanted with left ventricular assist devices (LVADs), 16 explanted (recovered), and 20 moderate-to-severe heart failure patients. Peak oxygen consumption was only highly correlated with peak cardiac power output in explanted LVAD (r = 0.85, P< 0.01), but not in implanted LVAD and heart failure patients (r = 0.55 and 0.53, P< 0.05). The anaerobic threshold was only modestly correlated with peak cardiac power output in heart failure and explanted (r = 0.46 and 0.54, P< 0.05) and weakly in implanted LVAD patients (r = 0.37, P< 0.05). Peak cardiac power output was well correlated with peak circulatory power in LVAD explanted and implanted (r = 0.82, P< 0.01; r = 0.63, P< 0.01) but not in heart failure patients (r = 0.31, P> 0.05). Ventilatory efficiency slope was only moderately correlated with peak cardiac power output in LVAD-explanted patients (r = -0.52, P< 0.05). Exercise-derived prognostic indicators demonstrate limited capacity in reflecting cardiac pumping capability in patients treated with LVADs and should therefore be used with caution in interpretation of cardiac organ function.

Association between right ventricular two-dimensional strain and exercise capacity in patients with either idiopathic or ischemic dilated cardiomyopathy

To detect right ventricular myocardial function in dilated cardiomyopathy (DCM) using two-dimensional strain echocardiography (2DSE) and to evaluate the relationship between right ventricular dysfunction and response to cardiopulmonary exercise test (CPET). Seventy-five DCM patients (44 idiopathic and 31 ischemic) without clinical signs of right ventricular failure underwent standard echo, 2DSE analysis of right ventricle and bicycle CPET. The two groups were comparable for clinical and standard two-dimensional echocardiographic and Doppler variables, except for right ventricular diameters that were mildly increased in patients with idiopathic DCM. Right ventricular global longitudinal strain (RV GLS) and regional peak myocardial right ventricular strain were significantly impaired in patients with idiopathic DCM compared with ischemic DCM (both P<0.001). A significant correlation was detectable among RV GLS and VO2 peak percentage (r= -0.65, P<0.0001), VE/VCO2 slope (r=0.35, P<0.01), maximum work rate percentage (r= -0.55, P<0.001) and peak circulatory power (r=0.53, P<0.001). These correlations with RV GLS remained significant even in multivariate analysis. 2DSE represents a promising noninvasive technique to assess right ventricular myocardial function in patients with DCM. Reduced right ventricular myocardial deformation is related to decreased ability to perform aerobic exercise and work rate, and to impaired ventilatory response.