Independent Predictors Of Exercise Capacity Research Articles

Left Atrial Myopathy is Associated With Exercise Incapacity and Ventilatory Inefficiency in Hypertrophic Cardiomyopathy.

Left atrial (LA) myopathy is an established component of hypertrophic cardiomyopathy (HCM); however, the data about its association with exercise incapacity or ventilatory inefficiency that may be seen in HCM patients are limited. This study aimed to explore the association between LA myopathy, evaluated by echocardiography LA strain, and exercise capacity and ventilatory efficiency, evaluated by cardiopulmonary exercise testing (CPET), in HCM patients. This study included 241 consecutive HCM patients (aged 51.2±15.7 years 67.2% male) in sinus rhythm who underwent CPET and transthoracic echocardiography at the same visit. Exercise incapacity (maximal/predicted oxygen consumption [%peakVO2] <80%) and ventilatory inefficiency (ventilation/carbon dioxide output [VE/VCO2] slope >34) were assessed by CPET. Left atrial myopathy was examined by speckle-tracking myocardial deformation parameters: LA reservoir, conduit and booster strain. All three LA strain values were univariate predictors of exercise capacity and ventilatory efficiency. Among them, LA reservoir strain had the higher r correlation coefficient for predicting both %peakVO2 and VE/VCO2 slope. Left atrial reservoir strain, presence of angina and family history of HCM were independent predictors of exercise capacity. Left atrial reservoir strain, male gender and non-sustained ventricular tachycardia were independent predictors of ventilatory efficiency. Left atrial reservoir strain was a significant predictor of %peakVO2<80% with an optimal cut-off value of 27% (sensitivity 87% and specificity 31%) and VE/VCO2>34 with an optimal cut-off value of 18% (sensitivity 71% and specificity 83%). Left atrial myopathy, as reflected by the LA strain values, was associated with exercise incapacity and ventilatory inefficiency in HCM individuals. Left atrial reservoir strain was the only common independent predictor of %peakVO2 and VE/VCO2 slope.

Early Determinants of Adverse Motor Outcomes in Preschool Children with a Critical Congenital Heart Defect.

Neurodevelopmental disabilities are common in infants with critical congenital heart disease (CCHD). A prospective, longitudinal cohort study was conducted to establish the prevalence and early determinants of adverse motor outcomes in infants who underwent cardiac surgery with cardiopulmonary bypass before six months of age. Motor development was assessed in 147 preschoolers using the Movement Assessment Battery for children-II. Although the majority displayed an average motor development, 22% of preschool children with CCHD deteriorated in their motor developmental score compared to their previous assessment at 18 months, especially in those with an aortic arch anomaly (AAA) (35%). Individual stability over time appeared to be moderate and the number of children with a motor delay increased, up to 20% in children with AAA. Motor development up to 42 months was best predicted by gestational age, cardio pulmonary bypass time, aortic cross clamp time, number of heart catheterizations up to 18 months and early motor outcomes. The increase in number of preschool children with a motor delay underlines the importance of longitudinal screening of motor skills in children with CCHD at risk for adverse motor outcomes. Offering early interventions may protect their current and future cardiovascular health as motor development is an independent predictor of exercise capacity, physical activity and participation in daily living.

Left atrial myopathy is associated with exercise capacity and ventilatory efficiency in hypertrophic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: None. Background Data about the predictive value of left atrial (LA) myopathy for exercise capacity and ventilatory efficiency in patients with hypertrophic cardiomyopathy (HCM) are limited. Purpose The aim of this study was to evaluate the association of LA myopathy, evaluated by echocardiography LA strain, with exercise capacity and ventilatory efficiency, evaluated by cardiopulmonary exercise testing (CPET), in HCM patients. Methods In total, 241 consecutive HCM patients (51 ± 16 years old; 67.2% male) on sinus rhythm that underwent CPET and transthoracic echocardiography at the same visit were studied. Exercise capacity (maximal oxygen consumption/predicted [%peakVO2]) and ventilatory efficiency (ventilation/carbon dioxide output [VE/VCO2] slope) were assessed by CPET. LA myopathy was examined by speckle tracking myocardial deformation parameters: LA reservoir, conduit and booster strain. Results All the three LA strain values were univariate predictors of exercise capacity and ventilatory efficiency. Among them, LA reservoir strain had the higher r correlation coefficient for predicting both %peakVO2 and VE/VCO2 slope and was included in multivariable analyses. LA reservoir strain, male gender and E/E’ ratio were independent predictors of exercise capacity. LA reservoir strain, male gender, non-sustained ventricular tachycardia and LA volume index were independent predictors of ventilatory efficiency (Table). Conclusion LA myopathy, as reflected by the LA strain values, was associated with exercise capacity and ventilatory efficiency in HCM individuals. LA reservoir strain was the only common independent predictor for %peakVO2 and VE/VCO2 slope. Abstract Table

Sex related differences in exercise performance in patients with hypertrophic cardiomyopathy: Hemodynamic insights through non-invasive pressure volume analysis

BackgroundWomen with HCM have worse cardiopulmonary exercise performance compared to men. We used non-invasive pressure-volume (PV) analysis to delineate sex related hemodynamic differences in HCM. MethodsPV loops were constructed from echocardiograms using left ventricular (LV) volumes indexed to body surface area, Doppler estimates of LV end-diastolic pressure and blood pressure. The end-systolic PV relationship (ESPVR) and end-diastolic PV relationship (EDPVR) were derived from validated single-beat techniques. The area between the ESPVR and EDPVR (isovolumetric PV area), was indexed to an LV end-diastolic pressure of 30 mmHg (PVAiso30), as the integrated metric of LV function. LV volume at an end-diastolic pressure of 30 mmHg (V30) indexed ventricular capacity. Results202 patients were included, 56 women. Women were older (51 vs 44 years, p = 0.012) and had reduced exercise capacity (5.6 vs 6.9 METs, p < 0.001). Only 32 patients (16%) had a peak gradient >30 mmHg at rest with no sex differences. Women had significantly lower indexed PVAiso30 (9094 vs 10,255 mmHg*mL/m2, p = 0.02) driven by reduced ventricular capacitance (V30 54 vs 62 mL/m2, p < 0.001). In multivariable linear regression indexed V30 was an independent predictor of exercise capacity. ConclusionImpaired exercise capacity in women with HCM appears associated with abnormalities in passive diastolic properties, suggesting a unique pathophysiology compared to men, and a potential difference in viable therapeutic molecular targets.

Sex related differences in exercise performance in patients with hypertrophic cardiomyopathy: hemodynamic insights through non-invasive pressure volume analysis

Abstract Background Women with HCM have worse cardiopulmonary exercise performance compared to men. We used non-invasive pressure-volume (PV) analysis to delineate sex related hemodynamic differences in HCM. Methods PV loops were constructed from echocardiograms using left ventricular (LV) volumes indexed to body surface area, Doppler estimates of LV end-diastolic pressure and blood pressure. The end-systolic PV relationship (ESPVR) and end-diastolic PV relationship (EDPVR) were derived from validated single-beat techniques. The area between the ESPVR and EDPVR (isovolumetric PV area), was indexed to an LV end-diastolic pressure of 30mmHg (PVAiso30), as the integrated metric of LV function. LV volume at an end-diastolic pressure of 30mmHg (V30) indexed ventricular capacity. Results 202 patients were included, 56 women. Women were older (51 vs 44 yrs, p=0.012) and had reduced exercise capacity (5.6 vs 6.9 METs, p&amp;lt;0.001). Only 32 patients (16%) had a peak gradient &amp;gt;30mmHg at rest with no sex differences. Women had significantly lower indexed PVAiso30 (6577 vs 7767 mmHg·mL/m2, p&amp;lt;0.001) driven by reduced ventricular capacitance (V30 54 vs 62 ml/m2, p&amp;lt;0.001). In multivariable linear regression indexed V30 was an independent predictor of exercise capacity. Conclusion Impaired exercise capacity in women with HCM appears strongly related to abnormalities in passive diastolic properties, suggesting a unique pathophysiology compared to men, and a potential difference in viable therapeutic molecular targets Funding Acknowledgement Type of funding sources: None.

Reduced Forced Vital Capacity and the Number of Chest Wall Surgeries are Associated with Decreased Exercise Capacity in Children with Congenital Heart Disease.

Low forced vital capacity (FVC) is associated with decreased exercise capacity in CHD. Multiple prior cardiac surgeries have been associated with low FVC. We seek to understand the relationship between low FVC, number of cardiac surgeries and cardiopulmonary response leading to decreased exercise capacity. Retrospective chart review of demographics, surgical history and exercise testing including spirometry was performed in patients with CHD. Single ventricle patients were excluded. Low FVC was defined as a Z-score below the lower limit of normal. Exercise parameters were expressed as a percent of predicted. There were 93 patients with 2 ventricle CHD identified over 34months with cardiopulmonary exercise testing. The FVC Z-score directly correlated with peak V̇O2% (R2 = 0.07, p < 0.05), and the O2 pulse% (R2 = 0.25, p < 0.0001). The VE/VCO2 was inversely related to the FVC Z-score (R2 = 0.11, p < 0.01). Patients with minimum three prior surgeries had decreased peak VO2% (63.7 vs. 72.8, p < 0.05), decreased peak O2 pulse% (80.8 vs. 97.9, p < 0.01) and a lower mean FVC Z-score (- 1.9 vs - 0.38, p < 0.01). The FVC Z-score and number of surgeries both predicted peak V̇O2% in multivariate analysis. Our study demonstrated that low FVC and three or more prior cardiac surgeries were associated with lower exercise capacity and lower stroke volume response. More cardiac surgeries were also associated with low FVC. However, both low FVC and the number of surgeries were independent predictors of exercise capacity.

Exercise Capacity and Functional Status in Liver Transplant Candidates: Identifying perceived determinants and consequences

Purpose: Exercise capacity is an independent predictor of the disease prognosis in many clinical conditions. This study aims to predict the functional exercise capacity determinants and investigate the association between the functional status variables in liver transplant candidates. &#x0D; Methods: This prospective cross-sectional study consisted of thirty patients who were scheduled for liver transplantation. Respiratory and peripheral muscle strengths were measured using a mouth pressure device and a hand-held dynamometer, respectively. Dyspnea, physical activity, fatigue, exercise capacity, physical performance, and quality of life of participants were evaluated using the Modified Borg Scale, the International Physical Activity Questionnaire, the Turkish version of the Checklist Individual Strength Questionnaire, the Six-minute Walk Test, the 30-sec Sit-to-Stand Test, and the Liver Disease Symptom Index 2.0, respectively. A multivariate linear regression analysis was conducted to identify independent predictors of exercise capacity. &#x0D; Results: The six-minute walk distance was inversely and strongly correlated with dyspnea (r=−0.668, p

Abstract 12992: LA Strain Predicts Exercise Capacity in Chronic Kidney Disease

Background: Left atrial (LA) function plays a pivotal role in modulating left ventricular performance particularly during exercise. The aim of our study was to evaluate the relationship between resting LA function by strain analysis as a determinant of exercise capacity in chronic kidney disease (CKD) patients, and evaluate its utility compared to exercise E/e’. Methods: Consecutive Stage 3 and 4 CKD patients without prior cardiac history were prospectively recruited from outpatient nephrology clinics and underwent clinical evaluation, resting and exercise stress echocardiography. Patients needed to be in sinus rhythm without significant valvular disease or ischaemia on stress testing. Resting echocardiographic parameters including E/e’ and phasic LA strain [LA reservoir (LASr), conduit (LAScd) and contractile (LASct) strain] were measured and compared to exercise E/e’. Results: 218 (63.9±11.7yrs, 64% men) CKD patients were recruited. Independent clinical predictors of exercise capacity were age, eGFR, body mass index and gender (p&lt;0.01 for all) while independent resting echocardiographic predictors included E/e’, LASr and LASct (p&lt;0.01 for all). Amongst independent resting echocardiographic predictors, LASr ( r =0.70,p&lt;0.01) demonstrated the strongest correlation to METs achieved. Receiver operating characteristic curves (Figure 1) demonstrated that LASr (AUC 0.83,) had similar predictive value as exercise E/e’ (AUC 0.79; AUC difference of 0.05, p=0.20 on DeLong test). A model combining LASr and clinical metrics showed robust predictive capacity for METs achieved in CKD patients. Conclusions: LASr, a marker of decreased LA compliance is an independent predictor of exercise capacity in Stage 3 and 4 CKD patients, with similar predictive value to exercise E/e’. The use of LASr may serve as a resting biomarker of functional capacity in this population.

Abstract 14611: Indices of Myocardial Work is an Independent Predictor of Exercise Capacity

Introduction: Exercise capacity has been shown to be an independent determinant of cardiovascular outcomes and prognosis. Conventional measures of left ventricular (LV) diastolic dysfunction, including E/e’ and left atrial (LA) metrics, have been shown to be independent predictors of exercise capacity however little is known about its relationship to myocardial energy utility and expenditure. Myocardial work (MW) is a novel non-invasive modality for assessment of myocardial efficiency and may serve to better define this relationship. Hypothesis: Greater wasted myocardial work is associated with reduced exercise capacity. Methods: Patients without prior cardiac disease referred to our echocardiography service for stress echocardiograms were prospectively recruited. These patients underwent comprehensive baseline transthoracic echocardiography (TTE) followed by exercise stress echocardiography. Only patients without structural heart disease on TTE and without ischaemia on stress testing were included. Myocardial work was assessed using EchoPac (v2.2, Chicago Illinois). Reduced exercise capacity was defined as METS achieved of ≤7. Results: 100 consecutive patients meeting inclusion criteria were analysed (45% male, age 56.0±15.7), of which 67% had diabetes and 44% had hypertension. The mean METS achieved was 8.5±3.7. Thirty-nine patients had a poor exercise capacity defined as METS achieved of ≤7. These patients were of older age, had greater indexed LV mass, higher E/e’, larger indexed left atrial volume, greater constructive work, greater wasted work, greater work index and lower work efficiency. On logistics regression, age (p&lt;0.001), and myocardial wasted work (p=0.02) were independent predictors of poor exercise capacity after adjusting for the other clinical and echocardiographic variables. Conclusions: Reduced exercise capacity is independently associated with greater wasted work. Larger studies will be required to validate our findings.

Poor right ventricular function is associated with impaired exercise capacity and ventilatory efficiency in transthyretin cardiac amyloid patients.

CardioPulmonary Exercise Test (CPET) is the gold standard to evaluate functional capacity in patients at high risk of heart failure (HF). Few studies with a limited number of subjects and conflicting results, analyzed the role of CPET in patients with systemic amyloidosis. Aims of our study were the assessment of the response to exercise in patients with Transthyretin amyloid (ATTR) cardiomyopathy (CA), and the correlation of clinical, biohumoral and echocardiographic parameters with CPET parameters, such as VO2 peak and VE/VCO2 slope. From February 2018 to March 2019, 72 cardiac ATTR patients were prospectively enrolled and underwent a complete clinical, biohumoral, echocardiographic and CPET assessment. All patients completed the exercise stress test protocol, without any adverse event. At CPET, they achieved a mean VO2 peak of 14mL/Kg/min and a mean VE/VCO2 slope of 31. The blood pressure response to exercise was inadequate in 26 (36%) patients (flat in 25 and hypotensive in 1), while 49/72 patients (69%) showed an inadequate heart rate recovery. In multivariate analysis, s' tricuspidalic was the only independent predictor of VO2 peak, while in the two test models performed to avoid collinearity, both TAPSE and s' tricuspidalic were the strongest independent predictors of VE/VCO2 slope. Our data demonstrate the role of right ventricular function as an independent predictor of exercise capacity and ventilatory efficiency in ATTR. In CPET evaluation, a significant proportion of patients presented an abnormal arterial pressure response and heart rate variation to exercise.

Impaired myocardial reserve underlies reduced exercise capacity and heart rate recovery in preterm-born young adults.

Aims We tested the hypothesis that the known reduction in myocardial functional reserve in preterm-born young adults is an independent predictor of exercise capacity (peak VO2) and heart rate recovery (HRR).Methods and results We recruited 101 normotensive young adults (n = 47 born preterm; 32.8 ± 3.2 weeks’ gestation and n = 54 term-born controls). Peak VO2 was determined by cardiopulmonary exercise testing (CPET), and lung function assessed using spirometry. Percentage predicted values were then calculated. HRR was defined as the decrease from peak HR to 1 min (HRR1) and 2 min of recovery (HRR2). Four-chamber echocardiography views were acquired at rest and exercise at 40% and 60% of CPET peak power. Change in left ventricular ejection fraction from rest to each work intensity was calculated (EFΔ40% and EFΔ60%) to estimate myocardial functional reserve. Peak VO2 and per cent of predicted peak VO2 were lower in preterm-born young adults compared with controls (33.6 ± 8.6 vs. 40.1 ± 9.0 mL/kg/min, P = 0.003 and 94% ± 20% vs. 108% ± 25%, P = 0.001). HRR1 was similar between groups. HRR2 decreased less in preterm-born young adults compared with controls (−36 ± 13 vs. −43 ± 11 b.p.m., P = 0.039). In young adults born preterm, but not in controls, EFΔ40% and EFΔ60% correlated with per cent of predicted peak VO2 (r2 = 0.430, P = 0.015 and r2 = 0.345, P = 0.021). Similarly, EFΔ60% correlated with HRR1 and HRR2 only in those born preterm (r2 = 0.611, P = 0.002 and r2 = 0.663, P = 0.001).Conclusions Impaired myocardial functional reserve underlies reductions in peak VO2 and HRR in young adults born moderately preterm. Peak VO2 and HRR may aid risk stratification and treatment monitoring in this population.

Psychological Well-Being as an Independent Predictor of Exercise Capacity in Cardiac Rehabilitation Patients With Obesity.

Objective: Exercise capacity (EC) is a well-established predictor of cardiovascular health. It is notoriously influenced by several factors, but the independent effect of psychological well-being (PWB) on EC has not yet been explored. The present study aims to investigate (1) whether PWB is an independent predictor of EC over and above selected demographic, behavioral, and biomedical parameters in a sample of CR patients with obesity and (2) whether PWB is a stronger predictor of EC than the other variables.Methods: Data from 1968 patients were collected at the time of their inclusion in a cardiac rehabilitation (CR) program and retrospectively analyzed in a cross-sectional study. Since cardiorespiratory parameters defined in normal weight populations differ from those of their obese counterparts, an ad hoc validated formula taking body mass index (BMI) into consideration was used to predict EC.Results: A multiple regression analysis revealed left ventricular eject fraction (LVEF) to be the strongest predictor of EC, followed by PWB, type 2 diabetes (DM), smoking status, atrial fibrillation (AF), and education. Bayesian evaluation of informative hypotheses corroborated LVEF as the best predictor of EC, and confirmed the superiority of PWB over and above DM and smoking status in influencing EC.Conclusion: These findings strengthen the link between psychological and physical health, suggesting a better PWB is associated with greater EC. Prompt screening of a patient’s mood and readiness to perform an active lifestyle would therefore enhance the long-term health benefits of CR.

Impaired left ventricular mechanics and functional reserve are associated with reduced exercise capacity in patients with hypertrophic cardiomyopathy.

Reduced metabolic equivalents (METs) are an indicator of exercise intolerance, which predicts poor prognosis in hypertrophic cardiomyopathy (HCM) patients. We sought to evaluate the changes in left ventricular (LV) mechanics and functional reserves, as well as their association with functional capacity in HCM patients. Seventy HCM patients and thirty controls were included in this study. LV mechanics were evaluated at rest and during exercise by echocardiography and two-dimensional speckle-tracking imaging to obtain parameters of functional reserve, LV global longitudinal strain (LVGLS), strain rate (SR), and circumferential strain. Hypertrophic cardiomyopathy (HCM) patients had lower LVGLS, systolic SR, early and late diastolic SR at rest and during exercise, and reduced absolute and relative systolic and diastolic reserve compared to controls. LV circumferential strain was significantly higher at rest but lower during exercise in HCM patients. Exercise capacity was markedly reduced in HCM patients, and peak exercise LVGLS (LVGLS-exe) significantly correlated with exercise capacity. Multivariate regression analyses showed that LVGLS-exe, LV filling pressure during exercise (E/e'-exe), and LV mass index (LVMI) were independent predictors of exercise capacity. Moreover, LVGLS-exe displayed incremental predictive value over E/e'-exe and LVMI for exercise intolerance. Receiver operating characteristic curve analysis showed LVGLS-exe had optimal accuracy for predicting exercise intolerance in HCM patients. Hypertrophic cardiomyopathy (HCM) patients have reduced LV mechanics at rest and during exercise and impaired mechanical reserve. LVGLS-exe is associated with exercise capacity and is an optimal predictive value for reduced exercise capacity in HCM patients.

Exercise capacity in asymptomatic patients with significant primary mitral regurgitation: independent effect of global longitudinal left ventricular strain.

Despite preserved left ventricular ejection fraction (LVEF), patients with significant primary mitral regurgitation (MR) often have reduced exercise capacity. In asymptomatic patients with ≥3+ primary MR undergoing rest-stress echocardiography (RSE), we sought to evaluate the incremental impact of left ventricular global longitudinal strain (LV-GLS) on exercise capacity. A total of 660 asymptomatic patients with ≥3+ primary MR, non-dilated LV and LVEF ≥60% (mean age, 57±14 years, 66% men, body mass index or BMI 25±4 kg/m2) who underwent RSE at our center between 2001 and 2013 were included. Standard RSE data were obtained. Average resting LV-GLS was measured using Velocity Vector Imaging. Mean mitral effective regurgitant orifice, resting right ventricular systolic pressure (RVSP) and LV-GLS were 0.45±0.2 cm2, 31±12 mmHg and -21.7%±2%, respectively; 28% had flail mitral leaflet. Mean metabolic equivalents (METs) and post-stress RVSP were 9.9±3, and 46±15 mmHg; 28% achieved <100% age-gender predicted METs. No patient had ischemia or significant arrhythmias. On logistic regression, resting LV-GLS [odds ratio (OR), 1.40, 95% confidence interval (CI): 1.21-1.55, BMI (OR, 1.11, 95% CI: 1.06-1.17)] and resting RVSP 1.22 (1.02-1.49) were independent predictors of exercise capacity. Area under the curve for association between 100% age-gender predicted METs and various factors were as follows: (I) BMI (0.60, 95% CI: 0.55-0.65, P<0.001); (II) resting RVSP (0.57, 95% CI: 0.52-0.62, P=0.006) and LV-GLS (0.66, 95% CI: 0.61-0.70, P<0.001). In asymptomatic patients with ≥3+ primary MR, non-dilated LV and preserved LVEF, LV-GLS is independently associated with exercise capacity, beyond known predictors.

Systolic Function of Right Ventricular Outflow Tract is a Better Predictor to Exercise Performance After Pulmonary Valve Replacement in Tetralogy of Fallot.

Debate on the proper timing of pulmonary valve replacement (PVR) after repair of tetralogy of Fallot is still continuing. We aim to clarify how the different components of right ventricle (RV) changed with relieved volume overload in the remodeling process after pulmonary valve replacement and gain a clear idea of the relationship between different right ventricle components function and exercise capacity after PVR in these patients. The medical records and results of cardiac magnetic resonance imaging and cardiopulmonary exercise testing of 25 consecutive eligible patients were reviewed. End-diastolic, end-systolic, and ejection fraction (EF) were determined for the total RV and its components before and after PVR. There was a marked increase in EF for the outlet after PVR (39.5±11.4 vs. 45.6±12.7, P=0.04); however, EF and volume change for the other components showed no significant difference. Peak oxygen consumption (VO2) correlated better with the RV outflow tract EF than with the EF of other components of the RV or the global EF (r=0.382, P=0.018), and the time interval between initial repair and PVR showed a significant correlation with peak VO2 (r=-0.339, P=0.037). Multivariate analysis showed the RV outflow tract EF to be the only independent predictor of exercise capacity (β=0.479; P=0.046). The systolic function of the RV outflow tract could be a reliable determinant of intrinsic RV performance in repaired TOF (rTOF) patients and a promising parameter for deciding timing of pulmonary valve replacement so as to achieve the best possible exercise capacity in repaired TOF patients.

Right ventricular outflow tract systolic function correlates with exercise capacity in patients with severe right ventricle dilatation after repair of tetralogy of Fallot.

The relationship between exercise capacity and right ventricular (RV) components function in repaired tetralogy of Fallot patients with severely dilated right ventricles is poorly understood. The aim of this study was to characterize the exercise capacity and its relationship to RV global and components function in repaired tetralogy of Fallot patients with RV end-diastolic volume index >150 ml/m 2 , a currently accepted threshold for pulmonary valve replacement. The medical records and results of cardiac magnetic resonance imaging and cardiopulmonary exercise testing of 25 consecutive eligible patients were reviewed. Twenty age- and gender-matched normal subjects were enrolled as cardiac magnetic resonance control. End-diastolic, end-systolic and stroke volumes, and ejection fraction (EF) were determined for the total RV and its components. Of the 25 patients, 44% maintained normal exercise capacity. RV outlet EF was higher ( P = 0.02) and RV incisions smaller ( P = 0.04) in patients with normal exercise capacity than those with subnormal exercise capacity. Predicted peak oxygen consumption correlated better with the RV outflow tract EF than with the EF of other components of the RV or the global EF ( r = 0.59; P = 0.002). Multivariate analysis showed the RV outflow tract EF to be the only independent predictor of exercise capacity (ß = 0.442; P = 0.02). Exercise capacity is preserved in some tetralogy of Fallot patients with severe RV dilatation. RV outflow tract EF is independently associated with exercise capacity in such patients, and could be a reliable determinant of intrinsic RV performance.

Chronotropic Incompetence and its Relation to Exercise Intolerance in Chronic Obstructive Pulmonary Disease

BackgroundTo study the relationship between chronotropic incompetence (CI) and disease severity and to assess the effect of CI on exercise capacity in patients with chronic obstructive pulmonary disease (COPD). Materials and MethodsArterial blood gas analysis, pulmonary function test and cardiopulmonary exercise testing were conducted in 60 patients with stable COPD and 45 healthy volunteers. CI was defined using the chronotropic response index (CRI = (peak heart rate-resting heart rate) / (220-age-resting heart rate). Based on CRI, patients with COPD were divided into the normal chronotropic group (n = 23) and CI group (n = 37). ResultsCI was present in 61.7% of the patients with COPD. Exercise capacity (peak oxygen uptake as percentage of predicted value, peak VO2%pred), peak heart rate and CRI were significantly lower in patients with COPD than in controls. However, resting heart rate was significantly higher than in controls. FEV1%pred and exercise capacity were significantly decreased in the CI group when compared with those in the normotropic group. There was significant association between CRI with FEV1%pred and peak VO2%pred. Multivariate regression analysis showed that CRI and FEV1%pred were independent predictors of exercise capacity in patients with COPD. A cutoff of 0.74 for the CRI showed a specificity of 94.1% in predicting patients with a peak VO2%pred < 60%. ConclusionsCRI was associated with disease severity in patients with COPD. CI may be an important parameter to reflect exercise capacity in patients with COPD.

Mechanisms of Effort Intolerance in Patients With Rheumatic Mitral Stenosis: Combined Echocardiography and Cardiopulmonary Stress Protocol

ObjectivesThis study sought to evaluate mechanisms of effort intolerance in patients with rheumatic mitral stenosis (MS). BackgroundCombined stress echocardiography and cardiopulmonary testing allows assessment of cardiac function, hemodynamics, and oxygen extraction (A–Vo2 difference). MethodsUsing semirecumbent bicycle exercise, 20 patients with rheumatic MS (valve area 1.36 ± 0.4 cm2) were compared to 20 control subjects at 4 pre-defined activity stages (rest, unloaded, anaerobic threshold, and peak). Various echocardiographic parameters (left ventricular volumes, ejection fraction, stroke volume, mitral valve gradient, mitral valve area, tissue s′ and e′) and ventilatory parameters (peak oxygen consumption [Vo2] and A–Vo2 difference) were measured during 8 to 12 min of graded exercise. ResultsComparing patients with MS to control subjects, significant differences (both between groups and for group by time interaction) were seen in multiple parameters (heart rate, stroke volume, end-diastolic volume, ejection fraction, s′, e′, Vo2, and tidal volume). Exercise responses were all attenuated compared to control subjects. Comparing patients with MS and poor exercise tolerance (<80% of expected) to other subjects with MS, we found attenuated increases in tidal volume (p = 0.0003), heart rate (p = 0.0009), and mitral area (p = 0.04) in the poor exercise tolerance group. These patients also displayed different end-diastolic volume behavior over time (group by time interaction p = 0.05). In multivariable analysis, peak heart rate response (p = 0.01), tidal volume response (p = 0.0001), and peak A–Vo2 difference (p = 0.03) were the only independent predictors of exercise capacity in patients with MS; systolic pulmonary pressure, mitral valve gradient, and mitral valve area were not. ConclusionsIn patients with rheumatic MS, exercise intolerance is predominantly the result of restrictive lung function, chronotropic incompetence, limited stroke volume reserve, and peripheral factors, and not simply impaired valvular function. Combined stress echocardiography and cardiopulmonary testing can be helpful in determining mechanisms of exercise intolerance in patients with MS.

Abstract 12795: Impact of Right Ventricular Outflow Tract Obstruction on Right Ventricular Remodeling and Exercise Capacity in Patients With Severe Pulmonary Regurgitation After Repair of Tetralogy of Fallot

Introduction: The long-term impact of right ventricular outflow tract obstruction (RVOTO) in patients with severe pulmonary regurgitation after repair of tetralogy of Fallot are controversial. Hypothesis: We hypothesize that patients with combined PR and RVOTO have better RV remolding and exercise capacity than patients with isolated PR. Methods: This is a retrospective cohort study of ninety-one consecutive patients with severe PR detected on echocardiography and evaluated with cardiac magnetic resonance and cardiopulmonary exercise test between 2012 and 2016. Twenty-three patients had combined PR and RVOTO (Doppler peak RVOT gradient ≥30 mmHg), while the other had isolated PR (n=68). Results: In spite of similar PR fraction between the two groups, patients with combined PR and RVOTO had significantly smaller RV end-diastolic volume (129.1 ± 32.7 vs 163.3 ± 53.9 ml/m 2 , p=0.020) and RV end-systolic volume (84.9 ± 26.5 vs 110.8 ± 48.2 ml/m 2 , P= 0.006) than patients with isolated PR. No significant difference was detected in RV ejection fraction and left ventricle volumes and function between the two groups. Multivariable linear regression analysis identified that transannular repair and peak pressure gradient of RVOT as independent predictors for RV volume. Patients with combined PR and RVOTO had higher (24.9 ± 5.2 vs 20.1 ± 6.3 ml/kg/min, P=0.07) peak oxygen uptake than patients with isolated PR. Peak RVOT gradient was the only independent predictor of exercise capacity in patients with combined PR and RVOTO. Conclusions: Patients with combined PR and RVOTO had less dilated RV and better exercise capacity than those with isolated PR. An acceptable residual RVOTO is more advantageous in the long-term outcome of repaired TOF.

Mechanisms of Effort Intolerance in Patients With Heart Failure and Borderline Ejection Fraction

Combining echocardiography and cardiopulmonary stress testing allows noninvasive assessment of hemodynamics, and oxygen extraction (A-VO2 difference). We evaluated mechanisms of effort intolerance in patients with heart failure with borderline (40% to 49%) left ventricular ejection fraction (EF) (HF and Borderline Ejection fraction). We included 89 consecutive patients with HF and Borderline Ejection fraction (n= 25; 63.6 ± 14years, 64% men), control subjects (n= 22), patients with HF with preserved EF (n= 26; EF ≥50%), and patients with HF with reduced EF (n= 16; <40%). Various echo parameters (left ventricular volumes, EF, stroke volume, mitral regurgitation [MR] volume, e', right ventricle end-diastolic area, and right ventricle end-systolic area), and ventilatory or combined parameters (peak oxygen consumption [VO2] and A-VO2 difference) were measured at 4 predefined activity stages. Effort-induced functional MR was frequent and more prevalent in HF and Borderline Ejection fraction than in all the other types of HF. In multivariable analysis heart rate response (p <0.0001), A-VO2 difference (p= 0.02), stroke volume (p= 0.002), and right ventricle end-systolic area were the only independent predictors of exercise capacity in HF and Borderline Ejection fraction but peak EF was not. In HF and Borderline Ejection fraction exercise intolerance is predominantly due to chronotropic incompetence, peripheral factors, and limited stroke volume reserve, which are related to right ventricle dysfunction and functional MR but not to left ventricular ejection fraction. Combined testing can be helpful in determining mechanisms of exercise intolerance in HF and Borderline Ejection fraction.