Cause Of Exercise Limitation Research Articles

Usefulness of cardiopulmonary exercise test combined with exercise stress echocardiography in mild chronic thromboembolic pulmonary disease.

Chronic thromboembolic pulmonary disease (CTEPD) can lead to exercise limitations even without right ventricular (RV) dysfunction or pulmonary hypertension at rest. Combining exercise stress echocardiography with cardiopulmonary exercise testing (ESE-CPET) for RV function and pressure changes combined measuring overall function may be useful for CTEPD evaluation. This study aims to investigate CPET and ESE results to elucidate the mechanisms of exercise limitation in mild CTEPD cases. Among our CTEPD registry, 50 patients who performed both right heart catheterization data of mild disease (less than 30mm Hg of mean pulmonary arterial pressure (mPAP)) and ESE-CPET were enrolled.Echocardiography and CPET-derived parameters were compared with hemodynamic parameters measured through right heart catheterization. Peak VO2 (maximal oxygen consumption) was decreased in overall population (71.3±16.3% of predictive value). Peak VO2 during exercise was negatively correlate with mPAP and pulmonary vascular resistance at rest. A substantial increase in RV systolic pressure (RVSP) was observed during exercise (RVSP: pre-exercise 37.2±11.8mm Hg, postexercise 64.3±24.9mm Hg, p-value<.001). Furthermore, RV function deteriorated during exercise when compared to the baseline (RV fractional area change: 31.5±10.0% to 37.8±7.0%, p-value<.001; RV global longitudinal strain: -17.1±4.2% to -17.7±3.3%, p-value<.001) even though basal RV function was normal. While an excessive increase in RVSP during exercise was noticed in both groups, dilated RV and RV dysfunction during exercise were demonstrated only in the impaired exercise capacity group. CTEPD patients with mild PH or without PH exhibited limited exercise capacity alongside an excessive increase in RVSP during exercise. Importantly, RV dysfunction during exercise was significantly associated with exercise capacity. ESE-CPET could aid in comprehending the primary cause of exercise limitation in these patients.

Intrapulmonary distribution of blood flow during exercise in pulmonary hypertension assessed by a new combination technique.

Hyperventilation and inadequate cardiac output (CO) increase are the main causes of exercise limitation in pulmonary hypertension (PH). Intrapulmonary blood flow partitioning between ventilated and unventilated lung zones is unknown. Thoracic impedance cardiography and inert gas rebreathing have been both validated in PH patients for non-invasive measurement of CO and pulmonary blood flow (PBF), respectively. This study sought to evaluate CO behaviour in PH patients during exercise and its partitioning between ventilated and unventilated lung areas, in parallel with ventilation partitioning between ventilated and unventilated lung zones. Eighteen PH patients (group 1 or 4) underwent a cardiopulmonary exercise test (CPET) with a three-step loaded workload protocol. The steps occurred at 0%, 20%, 40%, and 60% of peak workload reached during a preliminary maximum CPET. Ventilatory parameters, arterial blood gases, CO, PBF, and intrapulmonary shunt (calculated as the difference between CO and PBF) were obtained at each step, combining thoracic impedance cardiography and an inert gas rebreathing technique. Dead space ventilation observed throughout the exercise was about 40% of total ventilation. A progressive increase of CO from 4.86 ± 1.24 L/min (rest) to 9.41 ± 2.63 L/min (last step), PBF from 3.81 ± 1.41 L/min to 7.21 ± 2.93 L/min, and intrapulmonary shunt from 1.05 ± 0.96 L/min to 2.21 ± 2.28 L/min was observed. Intrapulmonary shunt was approximately 20% of CO at each exercise step. Although the study population was small, the combined non-invasive CO measurement seems a promising tool for deepening our knowledge of lung exercise haemodynamics in PH patients. This technique could be applied in future studies to evaluate PH treatment influences on CO partitioning, since a secondary increase of intrapulmonary shunt is undesirable.

Role of combined exercise stress echocardiography and cardiopulmonary exercise test in chronic thromboembolic disease

Abstract Background Chronic thromboembolic pulmonary disease (CTEPD) without pulmonary hypertension could cause significant exercise limitations. However, interventional or surgical treatments for CTEPD with mild pulmonary hypertension or normal pressure are on controversy. Purpose We aimed to evaluate cardiopulmonary function through cardiopulmonary exercise test (CPET) with stress echocardiography and to determine whether exercise pulmonary hypertension can explain exercise limitations in CTEPD patients with mPAP &amp;lt;30mmHg. Methods Patients diagnosed as CTEPD with mPAP less than 30mmHg was derived from our pulmonary hypertension center registry from April 2014 to October 2021.Transthoracic echocardiography (TTE) was performed at baseline (resting state) and immediately after CPET. TTE derived parameters and CPET parameters were compared with hemodynamic parameters measured by right catheterization. Results Total 37 patients were enrolled. Of these, Thirty-five patients had previously been diagnosed with CTEPH and had undergone PEA, BPA, or both. Most of the patients complained dyspnea of WHO functional class II or III. Pulmonary vascular resistance (PVR) was slightly higher than normal (185.0±102.2 dyne sec cm–5). Also VO2max was decreased in CPET (23.1±6.5 mL/kg/min). In correlation analysis, the higher the mPAP and PVR at rest, the lower VO2max during exercise. Meanwhile basal right ventricular (RV) function was normal, an increase in RVSP was notably observed during exercise (RVSP: pre-exercise 36.2±11.9, post-exercise 60.7±19.3, p value &amp;lt;0.001). Furthermore RV function deteriorated during exercise (TAPSE: pre-exercise 16.1±4.8, post-exercise 12.9±5.0, p value &amp;lt;0.001). Conclusions CTEPD patients with mild or normal PAP showed limited exercise capacity with exercise induced hypertension. Even in the mPAP less than 30mmHg, PVR and mPAP was significantly associated with exercise capacity. CPET with stress echocardiography could help to identify the main cause of exercise limitation in CTEPD patients and possibly provide the guideline for treatment plan. Funding Acknowledgement Type of funding sources: None.

Cardiopulmonary testing in adult patients with β-thalassemia major in comparison to healthy subjects

β-Thalassemia patients often have a reduced capacity of exercise and abnormal respiratory function parameters, but the reasons are unclear. In order to identify the causes of the exercise limitation, we performed a cardiopulmonary exercise testing (CPET) in a group of 54 adult β-thalassemia major (TM) patients without pulmonary arterial hypertension and in a group of healthy control subjects. All subjects underwent cardiac echocardiography and carried out pulmonary function tests. TM patients also filled an IPAQ questionnaire on usual physical activity (PA).Overall, TM patients have a diminished exercise performance in comparison to control subjects. In fact, peak oxygen uptake (V’O2 peak), expressing maximum exercise capacity, was decreased in 81.5% of the patients; similarly, anaerobic threshold (V’O2@AT) and O2 pulse also resulted lowered. In multivariable regression models adjusted for gender, age, BMI, and mean haemoglobin, V’O2 peak and O2 pulse were positively associated with cardiac iron overload (T2*). No ventilatory limitation to exercise was observed. The most important causes of exercise limitation in these patients were muscular deconditioning and reduced cardiac inotropism due to iron deposition. Only 15/54 (27.8%) TM patients used to perform vigorous physical activity. These results suggest that a program of regular physical activity may be useful to increase the tolerance to effort and therefore to improve the quality of life in these patients.

Cardiopulmonary Exercise Testing in Evaluation of Patients of Chronic Obstructive Pulmonary Disease

Objective assessment of severity in patients with chronic obstructive pulmonary disease (COPD) is mainly limited to pulmonary function testing performed at rest. But, accurate assessment of exercise capacity in patients with COPD may be possible with cardiopulmonary exercise testing (CPET). Forty-three patients with stable COPD were included and were divided into three groups based upon the spirometry data as per the Global Initiative for Obstructive Lung Disease (GOLD) guidelines as follows: Group A: mild COPD, Group B: moderately severe COPD and Group C: severe COPD. Symptom-limited CPET was performed using treadmill on incremental continuous ramp protocol in all of them. Five patients (11.6%) had mild COPD; 16 (37.2%) had moderately severe COPD and the remaining 22 (51.6%) patients had severe COPD. Anaerobic threshold was attained in all the 43 patients. The dominant symptom at peak exercise were dyspnoea (n = 19) and both dyspnoea and leg fatigue (n = 7). The other causes of exercise limitation included dyspnoea with significant oxygen desaturation (n = 6); and dyspnoea with severe oxygen desaturation (n = 2). Six patients complained only of leg fatigue at peak exercise. A significant correlation between forced expiratory volume in the first second (FEV1) percent predicted and the predicted maximum oxygen uptake (VO2 max % predicted) was observed in all the three groups (r = 0.39, p = 0.011) but with marked variability of peak VO2 for a given degree of airflow obstruction. Twenty-three (53.5%) patients with low anaerobic threshold (< 30%) were identified as potential group likely to benefit from exercise training for pulmonary rehabilitation. Cardiopulmonary exercise testing is useful to determine the causes of exercise limitation and to assess the maximal exercise capacity of patients with COPD.

Hypertrophic Cardiomyopathy as an Unexpected Mimic of Inducible Laryngeal Obstruction: The Case for Cardiopulmonary Exercise Testing in Otolaryngology

Inducible laryngeal obstruction is a common and challenging cause of exertional dyspnea. We report a case of an unanticipated cardiac condition that presented with symptoms suggestive of inducible laryngeal obstruction. A 55-year-old man was evaluated for progressive exertional dyspnea and throat tightness, unexplained after multiple medical evaluations. Resting laryngeal examination was suspicious for laryngopharyngeal reflux and mild vocal fold adduction during quiet expiration. Given progressive and refractory symptoms, maximal cardiopulmonary exercise testing with intermittent laryngeal examination was performed. This study excluded laryngeal causes of exercise limitation and led to an unexpected diagnosis of persistent atrial flutter and hypertrophic cardiomyopathy. Cardiopulmonary exercise testing with laryngeal examination can identify unexpected and life-threatening mimics of inducible laryngeal obstruction that may be missed by unmonitored exercise challenges. Suspicion for inducible laryngeal obstruction at rest may not predict the true nature of exercise limitation on cardiopulmonary exercise testing.

Reference Values for Chronotropic Index from 1280 Incremental Cycle Ergometry Tests.

Clinical cardiopulmonary exercise testing can determine causes of exercise limitation. The slope of heart rate (fC) versus oxygen uptake (V˙O2), which we call the chronotropic index (CI), can help identify cardiovascular impairment. We aimed to develop a reference equation for CI based on a large number of subjects considered to have normal exercise responses. From a database of 13,728 incremental cycle ergometry exercise tests, we identified 1280 normal tests based on the absence of a clinical diagnosis, normal body mass index, and normal aerobic performance plus absence of cardiovascular disease, medications, or ventilatory limitation. A linear mixed-model approach was used to analyze the relationship between CI and other variables. Subjects were age 18-84 yr, and 693 (54.1%) were men. Mean ± SD CI in men was lower than in women, 41.2 ± 9.3 beats per liter versus 63.4 ± 15.7 L. Age (in years), sex (0, male; 1, female), height (in centimeters), and weight (in kilograms) were significant predictors for CI:CIi = 106.9 + 0.16 × agei + 14.3 × sexi - 0.31 × heighti - 0.24 × weighti. The SE of estimates ranged from 10.6 to 11.2 L (median of 10.7 L). We report a reference equation for CI derived from normal subjects. The CI can be used in conjunction with V˙O2max to interpret maximal cardiopulmonary exercise tests. We consider a high CI to be cardiovascular impairment and a low CI plus low V˙O2max to be chronotropic insufficiency.

Persistent exercise intolerance after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension.

Haemodynamic normalisation is the ultimate goal of pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (CTEPH). However, whether normalisation of haemodynamics translates into normalisation of exercise capacity is unknown. The incidence, determinants and clinical implications of exercise intolerance after PEA are unknown. We performed a prospective analysis to determine the incidence of exercise intolerance after PEA, assess the relationship between exercise capacity and (resting) haemodynamics and search for preoperative predictors of exercise intolerance after PEA. According to clinical protocol all patients underwent cardiopulmonary exercise testing (CPET), right heart catheterisation and cardiac magnetic resonance (CMR) imaging before and 6 months after PEA. Exercise intolerance was defined as a peak oxygen consumption (V'O2 ) <80% predicted. CPET parameters were judged to determine the cause of exercise limitation. Relationships were analysed between exercise intolerance and resting haemodynamics and CMR-derived right ventricular function. Potential preoperative predictors of exercise intolerance were analysed using logistic regression analysis. 68 patients were included in the final analysis. 45 (66%) patients had exercise intolerance 6 months after PEA; in 20 patients this was primarily caused by a cardiovascular limitation. The incidence of residual pulmonary hypertension was significantly higher in patients with persistent exercise intolerance (p=0.001). However, 27 out of 45 patients with persistent exercise intolerance had no residual pulmonary hypertension. In the multivariate analysis, preoperative transfer factor of the lung for carbon monoxide (T LCO) was the only predictor of exercise intolerance after PEA. The majority of CTEPH patients have exercise intolerance after PEA, often despite normalisation of resting haemodynamics. Not all exercise intolerance after PEA is explained by the presence of residual pulmonary hypertension, and lower preoperative T LCO was a strong predictor of exercise intolerance 6 months after PEA.

Ventilatory compensation during the incremental exercise test is inversely correlated with air trapping in COPD.

Background: Air trapping and gas exchange abnormalities are major causes of exercise limitation in chronic obstructive pulmonary disease (COPD). During incremental cardiopulmonary exercise testing, actual nadir values of ventilatory equivalents for carbon dioxide (V E/VCO 2) and oxygen (V E/VO 2) may be difficult to identify in COPD patients because of limited ventilatory compensation capacity. Therefore, we aimed in this exploratory study to detect a possible correlation between the magnitude of ventilation augmentation, as manifested by increments in ventilatory equivalents from nadir to peak exercise values and air trapping, detected with static testing. Methods: In this observational study, we studied data obtained previously from 20 COPD patients who, during routine follow-up, underwent a symptom-limited incremental exercise test and in whom a plethysmography was obtained concurrently. Air trapping at rest was assessed by measurement of the residual volume (RV) to total lung capacity (TLC) ratio (RV/TLC). Gas exchange data collected during the symptom-limited incremental cardiopulmonary exercise test allowed determination of the nadir and peak exercise values of V E/VCO 2 and V E/VO 2, thus enabling calculation of the difference between peak exrcise value and nadir values of V E/VCO 2 and V E/VO 2, designated ΔV E/VCO 2 and ΔV E/VO 2, respectively. Results: We found a statistically significant inverse correlation between both ΔV E/VCO 2 (r = -0. 5058, 95% CI -0.7750 to -0.08149, p = 0.0234) and ΔV E/VO 2 (r = -0.5588, 95% CI -0.8029 to -0.1545, p = 0.0104) and the degree of air trapping (RV/TLC). There was no correlation between ΔV E/VCO 2 and forced expiratory volume in the first second, or body mass index. Conclusions: The ventilatory equivalents increment to compensate for acidosis during incremental exercise testing was inversely correlated with air trapping (RV/TLC).

Ventilatory compensation during the incremental exercise test is inversely correlated with air trapping in COPD

Background: Air trapping and gas exchange abnormalities are major causes of exercise limitation in chronic obstructive pulmonary disease (COPD). During incremental cardiopulmonary exercise testing, actual nadir values of ventilatory equivalents for carbon dioxide (V E/VCO 2) and oxygen (V E/VO 2) may be difficult to identify in COPD patients because of limited ventilatory compensation capacity. Therefore, we aimed in this exploratory study to detect a possible correlation between the magnitude of ventilation augmentation, as manifested by increments in ventilatory equivalents from nadir to peak exercise values and air trapping, detected with static testing. Methods: In this observational study, we studied data obtained previously from 20 COPD patients who, during routine follow-up, underwent a symptom-limited incremental exercise test and in whom a plethysmography was obtained concurrently. Air trapping at rest was assessed by measurement of the residual volume (RV) to total lung capacity (TLC) ratio (RV/TLC). Gas exchange data collected during the symptom-limited incremental cardiopulmonary exercise test allowed determination of the nadir and peak exercise values of V E/VCO 2 and V E/VO 2, thus enabling calculation of the difference between peak exrcise value and nadir values of V E/VCO 2 and V E/VO 2, designated ΔV E/VCO 2 and ΔV E/VO 2, respectively. Results: We found a statistically significant inverse correlation between both ΔV E/VCO 2 (r = -0. 5058, 95% CI -0.7750 to -0.08149, p = 0.0234) and ΔV E/VO 2 (r = -0.5588, 95% CI -0.8029 to -0.1545, p = 0.0104) and the degree of air trapping (RV/TLC). There was no correlation between ΔV E/VCO 2 and forced expiratory volume in the first second, or body mass index. Conclusions: The ventilatory equivalents increment to compensate for acidosis during incremental exercise testing was inversely correlated with air trapping (RV/TLC).

Cardiopulmonary Exercise Test in evaluation of Functional Capacity in patients with Chronic Obstructive Pulmonary Disease

Background: Assessment of severity in patients with Chronic Obstructive Pulmonary Disease(COPD) is usually done at rest by spirometry test. But cardiopulmonary exercise test can be a measure to assess the functional capacity more accurately in patients with COPD.&#x0D; Method: Fifty eight patients with stable COPD were included in this study period of one and half years from January 15 to June 2016 and categorise into four groups based on spirometric data following the GOLD guidelines 2018; GOLD 1 mild COPD, GOLD 2 moderate COPD, GOLD 3 severe COPD and GOLD 4 very severe COPD. Symptom limited CPET on treadmill using Bruce protocol using cardiopulmonary exercise machine was done in all fifty eight patient.&#x0D; Results: twenty one patients (36.20%) had moderate COPD; twenty six(44.82%) had severe COPD; eleven(18.96%) had very severe COPD and none found to be categorised as mild COPD. All fifty eight patients attained anaerobic threshold. Majority(34, 58.62%) of patients stopped exercise due to shortness of breath; decreased oxygen saturation was the cause of stopping exercise in eight(13.7%) patients; other causes of exercise limitation were increased heart rate, vertigo, leg fatigue, increased blood pressure, ventricular ectopic and chest tightness. Four patients were found to limit exercise due to combined shortness of breath and leg fatigue. A significant correlation between forced expiratory volume in first second (FEV1, percent predicted) and maximum oxygen uptake(ml/kg/min) was observe. Twenty(46.55%) patients with low(&lt;40%) AT were identified who could be benefited from pulmonary rehabilitation program.&#x0D; Conclusion: CPET can be useful to identifying the COPD patients with functional capacity impairment for pulmonary rehabilitation by assessing exercising capacity and the cause of exercise limitation.&#x0D; J Dhaka Medical College, Vol. 28, No.1, April, 2019, Page 23-27

CPAP Effect on Cardiopulmonary Exercise Testing Performance in Patients with Moderate-Severe OSA and Cardiometabolic Comorbidities.

Background and Objectives: Obstructive sleep apnea (OSA) is associated with daytime somnolence, cognitive impairment and high cardiovascular morbidity and mortality. Obesity, associated cardiovascular comorbidities, accelerated erythropoiesis and muscular mitochondrial energetic dysfunctions negatively influence exercise tolerance in moderate-severe OSA patients. The cardiopulmonary exercise testing (CPET) offers an integrated assessment of the individual’s aerobic capacity and helps distinguish the main causes of exercise limitation. The purpose of this study is to evaluate the aerobic capacity of OSA patients, before and after short-term continuous positive airway pressure (CPAP). Materials and Methods: Our prospective study included 64 patients with newly diagnosed moderate-severe OSA (apnea hypopnea index (AHI) 39.96 ± 19.04 events/h) who underwent CPET before and after CPAP. Thirteen patients were unable to tolerate CPAP or were lost during follow-up. Results: 49.29% of our patients exhibited a moderate or severe decrease in functional capacity (Weber C or D). CPET performance was influenced by gender but not by apnea severity. Eight weeks of CPAP induced significant improvements in maximal exercise load (Δ = 14.23 W, p = 0.0004), maximum oxygen uptake (Δ = 203.87 mL/min, p = 0.004), anaerobic threshold (Δ = 316.4 mL/min, p = 0.001), minute ventilation (Δ = 5.1 L/min, p = 0.01) and peak oxygen pulse (Δ = 2.46, p = 0.007) as well as a decrease in basal metabolic rate (BMR) (Δ = −8.3 kCal/24 h, p = 0.04) and average Epworth score (Δ = −4.58 points, p < 0.000001). Conclusions: Patients with moderate-severe OSA have mediocre functional capacity. Apnea severity (AHI) was correlated with basal metabolic rate, resting heart rate and percent predicted maximum effort but not with anaerobic threshold or maximum oxygen uptake. Although CPET performance was similar in the two apnea severity subgroups, short-term CPAP therapy significantly improved most CPET parameters, suggesting that OSA per se has a negative influence on effort capacity.

Cardiopulmonary limitation to exercise in systemic sclerosis: A Case-Control Study

Interstitial lung disease and pulmonary hypertension are the leading causes of morbidity and mortality in patients with systemic sclerosis (SSc). Exercise-induced dyspnea is the first manifestation of both complications, which explains why the value of resting tests to predict preclinical heart or lung involvement is limited. Cardiopulmonary exercise testing (CPET) offers a comprehensive approach to identify the cause of exercise limitation. However, the role of CPET in SSc patients without demonstrated cardiac and/or respiratory disease has not been extensively investigated. We sought to compare the cardiopulmonary adaptation to exercise of SSc patients without cardiac or pulmonary disease vs. healthy controls. SSc patients with normal resting echocardiography and pulmonary functional test, and healthy volunteers were prospectively enrolled. All underwent maximal CPET and results were compared after correction for age and gender. Thirty-nine patients (females 36, age 54 ± 12) and 43 healthy subjects (females 31, age 46 ± 11) were included between 07/2015 and 05/2018. Exercise capacity was lower in patients than in healthy subjects ( Table 1 ). Patients had lower oxygen uptake (VO2) at peak exercise and higher minute ventilation/carbon dioxide production (VE/VCO2) slope than controls ( Fig. 1 ). They had higher VE/VCO2 ratio and lower end-tidal pressure of CO2 (PetCO2) at the ventilatory threshold. Ventilatory reserve was preserved and peripheral oxygen saturation was normal in both groups. The combination of low peak VO2, high VE/VCO2 slope, low PetCO2, and high respiratory reserve suggest that patients with SSc without overt cardiac or respiratory disease present with a cardiovascular limitation to exercise. The latter may be related to latent cardiac dysfunction or pulmonary vascular disease.

CHRONOTROPIC INSUFFICIENCY AS CAUSE OF EXERCISE LIMITATION IN PATIENTS UNDERGOING CARDIOPULMONARY EXERCISE TESTING FOR DYSPNEA

SESSION TITLE: Tuesday Abstract Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: 10/22/2019 01:00 PM - 02:00 PM PURPOSE: Chronotropic incompetence is defined as the inability of the heart to increase its rate in response to increased activity or demand. It has been recognized as predictor for major cardiovascular event, mortality and exercise intolerance.The purpose of this study was to identify the proportion of patients who underwent cardiopulmonary exercise testing(CPET) in whom chronotropic incompetence was deemed to be the primary cause of exercise limitation and to describe the characteristic exercise response in these patients. METHODS: The results of all CPET studies done in a tertiary referral center from January 2015 to May 2018 were reviewed. The results of patients in whom chronotropic incompetence was inferred to be the primary cause of exercise limitation were analyzed to describe the characteristic exercise response. RESULTS: A total of 260 CPET studies were done during the study period. Chronotropic incompetence was identified as the primary cause of exercise limitation in 37(14%) of the studies. The mean maximum oxygen uptake(VO2) was normal at 81.78%(SD 18.97), mean VO2/kg was reduced at 65%(SD 13.5%). The mean resting heart rate(HR) was 67 (SD 11). Mean maximum HR was reduced at 103 (SD 19). Mean maximum HR percent predicted was reduced at 67%(SD 9.5). Mean oxygen(O2) pulse was increased at 122% (SD 22). Mean maximum ventilation (Ve) was normal at 53.5%(SD 10.66). Mean Respiratory exchange ratio (RER) 1.14 (SD 0.12). Information about the medication use was present in 24 of the 38 patients. Of the 24, 20 patients were on beta blockers, 2 were on calcium channel blockers and 2 were not on any AV nodal blocking agents. CONCLUSIONS: Chronotropic incompetence was the reason for exercise limitation in 14% of all patients that underwent cardiopulmonary exercise testing for evaluation of their dyspnea. These patients demonstrated a characteristic exercise response with preserved maximum oxygen uptake, decreased maximum heart rate, increased oxygen pulse and normal breathing reserve.The most common cause of chronotropic incompetence in this patient population was use of AV nodal blocking agents, specifically beta blockers. CLINICAL IMPLICATIONS: Chronotropic incompetence is an under recognized and under reported cause of exercise limitation in patients presenting with dyspnea. It is easily recognizable on cardiopulmonary exercise stress testing. The most common culprit are beta blockers. Clinicians need to be aware of the characteristic exercise response. If CI is present, clinicians should consider discontinuing beta blockers unless there is a strong indication. More research is needed to see if discontinuation of the culprit medications helps with decreasing dyspnea. The exact mechanism by which chronotropic incompetence could lead to dyspnea on exertion is not well known but could be due to increased left sided end diastolic pressures during exercise. DISCLOSURES: No relevant relationships by Abhishek Agarwal, source=Web Response No relevant relationships by Melvin Pratter, source=Web Response

P4437Exercise limitation in systemic sclerosis: a case-controlled study

Abstract Introduction Interstitial lung disease and pulmonary hypertension are the leading causes of morbidity and mortality in patients with systemic sclerosis (SSc). Exercise-induced dyspnea is the first manifestation of both complications, which explains why the value of resting tests to predict preclinical heart or lung involvement is limited. Cardiopulmonary exercise testing (CPET) offers a comprehensive approach to identify the cause of exercise limitation. However, the role of CPET in SSc patients without demonstrated cardiac and/or respiratory disease has not been extensively investigated. Aim We sought to compare the cardiopulmonary adaptation to exercise of SSc patients without cardiac or pulmonary disease vs healthy volunteers. Methods SSc patients (normal resting echocardiography and pulmonary functional test) and healthy volunteers were prospectively enrolled. They underwent maximal symptom-limited CPET, exercise echocardiography (EXEcho), and 6 minutes walk test. Results were compared after adjustment for age and gender. Results Thirty-nine patients (54±12 years) and 43 healthy subjects (46±11 years) were included. Workload was lower in patients than controls (84±42 vs 178±58 W, p&lt;0.001), with similar respiratory exchange ratio (1.27±0.11 vs 1.28±0.10, p=0.570) at peak exercise. Patients had lower oxygen uptake (VO2) at peak exercise (17±6 vs 30±8 ml min kg–1, p&lt;0.001), and higher minute ventilation/carbon dioxide production (VE/VCO2) slope (41±8 vs 33±5, p&lt;0.001) than controls (Figure 1). They had higher VE/VCO2 ratio (40±7 vs 30±3, p&lt;0.001) and lower end-tidal pCO2 (PetCO2) (35±5 vs 41±3 mmHg, p&lt;0.001) at the ventilatory threshold (VT). Respiratory reserve was preserved, and peripheral oxygen saturation was normal at peak exercise in both groups. Resting echocardiography revealed larger left atrium in SSc-patients (24±8 vs 20±7 ml/m2, p=0.013) and higher estimated left atrial pressure (LAP) (10±2 vs 8±2 mmHg, p=0.001) vs controls. At ExEcho, total pulmonary resistance (TPR) was higher (3.2±0.6 vs 2.6±0.5 WU, p=0.003) and right ventricular function markers were lower at peak exercise in patients vs controls, despite similar values at rest. Plasma NT-proBNP was within normal range in all patients. Walk distance was shorter in SSc-patients vs controls (505±80 vs 624±50 m, p&lt;0.001), and correlated with peak VO2, VE/VCO2 slope, and VE/VCO2 at VT. In Ssc patients, peak VO2 also correlated with DLCO (r=0.640, p&lt;0.001), with left atrial volume (r=−0.344, p=0.002), and with estimated LAP (r=−0.490, p&lt;0.001) but not with NT-proBNP or lung volumes. Conclusion The combination of low peak VO2, high VE/VCO2 slope, low PetCO2, and high respiratory reserve suggests that patients with SSc, without overt cardiac or respiratory disease, present with cardiovascular limitation to exercise. This may be related to latent cardiac dysfunction or pulmonary vascular disease. Acknowledgement/Funding This work was partially funded by research grants from GSK, Actelion, and from the Belgian Foundation for Cardiac Surgery.

Ventilatory compensation during the incremental exercise test is inversely correlated with air trapping in COPD

Background: Air trapping and gas exchange abnormalities are major causes of exercise limitation in chronic obstructive pulmonary disease (COPD). During incremental cardiopulmonary exercise testing, ventilatory equivalents for carbon dioxide (VE/VCO2) and oxygen (VE/VO2) may be difficult to identify in COPD patients because of limited ventilatory compensation capacity. Therefore, we aimed to detect a possible correlation between the magnitude of ventilation augmentation, as manifested by increments in ventilatory equivalents from nadir to peak effort values and air trapping, detected with static testing. Methods: In this observational study, we studied data obtained previously from 20 COPD patients who, during routine follow-up, underwent a symptom-limited incremental exercise test and in whom a plethysmography was obtained concurrently. Air trapping at rest was assessed by measurement of the residual volume (RV) to total lung capacity (TLC) ratio (RV/TLC). Gas exchange data collected during the symptom-limited incremental cardiopulmonary exercise test allowed determination of the nadir and peak effort values of VE/VCO2 and VE/VO2, thus enabling calculation of the difference between peak effort value and nadir values of VE/VCO2 and VE/VO2, designated ΔVE/VCO2 and ΔVE/VO2, respectively. Results: We found a statistically significant inverse correlation between both ΔVE/VCO2 (r = -0. 5058, 95% CI -0.7750 to -0.08149, p = 0.0234) and ΔVE/VO2 (r = -0.5588, 95% CI -0.8029 to -0.1545, p = 0.0104) and the degree of air trapping (RV/TLC). There was no correlation between ΔVE/VCO2 and peak oxygen consumption, forced expiratory volume in the first second, or body mass index. Conclusions: The ventilatory equivalents increment to compensate for acidosis during incremental exercise testing was inversely correlated with air trapping (RV/TLC) and may be a candidate prognostic biomarker.

Chronic iliofemoral vein obstruction – an under-recognized cause of exercise limitation

Local symptoms of chronic venous insufficiency after deep vein thrombosis (DVT) are well described, but little is known about the effect of residual venous obstruction on exercise capacity. We tested our hypothesis that chronic residual iliofemoral vein occlusion (IFVO) after DVT may impair exercise capacity. Nine post-DVT patients with residual IFVO and effort intolerance were studied; a comparison cohort consisted of 11 healthy volunteers. Exercise tolerance was assessed by bimodality incremental symptom-limited cardiopulmonary testing, using leg and arm ergometers. In healthy subjects, leg vein obstruction was modelled by application to the thighs of cuff tourniquets inflated to 30–40 mmHg. Leg exercise tolerance as measured by oxygen uptake at peak exercise (peak ⩒’O2) was reduced in patients (median 50% predicted (range 36–83%) vs. 88% predicted (67–129%) in normal subjects, p < 0.001). Arm exercise tolerance was also reduced in patients, but less severely than in the legs – the median arm: leg ratio of peak ⩒’O2 was 0.95 (0.77–1.43) in patients vs. a normal ratio of 0.73 (0.6–1.0) in healthy subjects (p < 0.003). In healthy subjects, bilateral leg vein obstruction by tourniquets reduced peak ⩒’O2 in leg exercise to 76% predicted (range 55–108%; p < 0.001 vs. standard test). In conclusion, the comparison of arm vs. leg exercise capacity in post-DVT patients with residual IFVO and the effect of experimental venous obstruction (thigh tourniquets) in healthy subjects suggest that reduced exercise capacity in patients was at least partially caused by reduced venous return. Chronic venous obstruction should be recognized as a cause of exercise limitation.

Perioperative cardiopulmonary exercise testing (CPET): consensus clinical guidelines on indications, organization, conduct, and physiological interpretation

The use of perioperative cardiopulmonary exercise testing (CPET) to evaluate the risk of adverse perioperative events and inform the perioperative management of patients undergoing surgery has increased over the last decade. CPET provides an objective assessment of exercise capacity preoperatively and identifies the causes of exercise limitation. This information may be used to assist clinicians and patients in decisions about the most appropriate surgical and non-surgical management during the perioperative period. Information gained from CPET can be used to estimate the likelihood of perioperative morbidity and mortality, to inform the processes of multidisciplinary collaborative decision making and consent, to triage patients for perioperative care (ward vs critical care), to direct preoperative interventions and optimization, to identify new comorbidities, to evaluate the effects of neoadjuvant cancer therapies, to guide prehabilitation and rehabilitation, and to guide intraoperative anaesthetic practice. With the rapid uptake of CPET, standardization is key to ensure valid, reproducible results that can inform clinical decision making. Recently, an international Perioperative Exercise Testing and Training Society has been established (POETTS www.poetts.co.uk) promoting the highest standards of care for patients undergoing exercise testing, training, or both in the perioperative setting. These clinical cardiopulmonary exercise testing guidelines have been developed by consensus by the Perioperative Exercise Testing and Training Society after systematic literature review. The guidelines have been endorsed by the Association of Respiratory Technology and Physiology (ARTP).

Limited Exercise Capacity in Patients with Systemic Sclerosis: Identifying Contributing Factors with Cardiopulmonary Exercise Testing.

Exercise limitation in patients with systemic sclerosis (SSc) is often multifactorial and related to complications such as interstitial lung disease (ILD), pulmonary vasculopathy (PV), left ventricular dysfunction (LVD), and/or peripheral/muscular limitation (PML). We hypothesized that cardiopulmonary exercise testing (CPET) could not only suggest and rank competing etiologies, but also highlight peripheral impairment. Clinical, resting pulmonary function testing, and CPET data from patients with SSc referred for exercise limitation between October 2009 and November 2015 were retrospectively analyzed in this bi-center study. Patients were categorized as having ILD, PV, LVD, and/or PML based on CPET response patterns and the diagnoses were matched with results from the reference investigations. The latter consisted of transthoracic echocardiography, chest computed tomography scan, and right heart catheterization (RHC). Twenty-seven patients presented with CPET profiles consistent with ILD (n = 16), PV (n = 15), LVD (n = 5), and PML (n = 19). None of the subjects had a normal CPET profile. There was a statistically significant negative correlation between resting DLCO, on the one hand, and dead space to tidal volume ratio and alveolar-arterial gradient [P(Ai-a)O2] on the other (p < 0.005). CPET identified 90% of patients with a mean pulmonary arterial pressure at rest ≥ 21 mmHg measured by RHC (n = 10). Peak P(Ai-a)O2, taken independently from other variables, was crucial in distinguishing subjects with ILD from those without ILD (p < 0.05). CPET is useful for the characterization of multifactorial exercise limitation in patients with SSc and in identifying SSc-related complications such as ILD and PV. This study also identifies PML as an underestimated cause of exercise limitation.

Effect of Body Mass Index on Exercise Capacity in Patients With Hypertrophic Cardiomyopathy

The objective of this study was to evaluate the relation between body mass index (BMI), exercise capacity, and symptoms in patients with hypertrophic cardiomyopathy (HC) and to utilize results of cardiopulmonary exercise tests (CPX) and transthoracic echocardiograms to understand the mechanism(s) of reduced exercise capacity across body mass index groups. Over a 6-year period, 510 consecutive patients with HC seen at a tertiary referral center underwent (CPX) and a transthoracic echocardiogram. Increasing BMI was associated with decreased exercise capacity as assessed by peak VO2 (ml/kg/min). However, the prevalence of cardiac impairment did not vary by BMI group. In conclusion, these findings suggest that in some patients with hypertrophic cardiomyopathy, cardiac impairment is not the primary cause of exercise limitation and weight loss may result in improved exercise capacity.