Limited value of anaerobic threshold for assessing functional capacity in patients with heart failure

Exercise tolerance was assessed in 146 patients with cardiac dysfunction in terms of anaerobic threshold (ATge). Patients were divided into four classes according to the peak oxygen uptake: Class A (72 patients) exceeding 1000 ml/min; Class B (27 patients) 800-999 ml/min; Class C (37 patients) 500-799 ml/min; and Class D (10 patients) below 500 ml/min. An incidence of the ATge breakpoint was lower in patients of Class C (38%) than in those of either Class B (70%, p < 0.05) or Class A (87%, p < 0.05). The ATge could not be determined in any patients in Class D. The V-slope method improved the ability to determine ATge by 20%. In Classes C and D, ATge detection was precluded considerably by the fact that the initial workloads of exercise test involved oxygen uptake levels already close to or above the ATge. An oscillatory hyperventilation pattern was also significantly related to failure in defining ATge in Class C patients. Of the 51 patients whose ATge was undetermined, 9 had an atrial septal defect In two of these, exercise-induced right-to-left shunting led to progressive arterial hypoxemia, and the consequent hyperventilation masked the appearance of ATge. Thus, ATge is virtually undetectable in patients with severe heart failure largely because of the early onset of anaerobic metabolism or abnormal ventilatory responses to exercise. Accordingly, the clinical application of ATge in the assessment of functional capacity would be limited to patients with mild to moderate heart failure.     

Exercise intolerance in patients with chronic heart failure: role of pulmonary diffusing limitation

In order to test the hypothesis of pulmonary diffusing capacityinvolvement in exercise limitation in subjects with chronicheart failure (CHF), lung transfer factor (TLCO), oxygen saturation(SaO₂), cardiac output (CO) and gas exchange were studied overthe course of an incremental exercise test in 10 patients and10 controls. Tlie TLCO and transfer coefficient for carbon monoxide(TLCOIVA) were measured at rest and during recovery by the singlebreath method. Tlie SaO₂ was followed non-invasively with afinger oximeter and CO was determined according to the carbondioxide rebreathing method. Analysis of respiratory variablesat maximal effort showed significantly lower values in patientswith CHF as regards peak oxygen uptake (VO₂), minute ventilation(VE), heart rate (HR), oxygen pulse (O₂ pulse), and CO withhigher ventilatory reserve (VR) than controls. At a comparableworkload (30 W), patients with CHF demonstrated higher valuesfor VE and lower values for CO than controls. The TLCO, expressedas percent of predicted values, was significantly lower in CHFpatients than controls, respectively, at rest (90.5 ±3.75%vs 106.8 ±3.8%) and within 5 min after maximal exercise(87 ±4.4% vs 117.4 +3.81%). Hie TLCOIVA showed comparabledata between the two groups at rest (81.7 ± 3.28 vs 90.3± 2.86%). However, significantly lower values of TLCOIVAwere obtained for CHF after maximal exercise in comparison tocontrol subjects (77.5 ±3.85% vs 96.3 ±3.95%). These results confirm the alteration of the main variables inrelation to cardiopulmonary exercise limitation in CHF, andindicate a significant decrease in TLCO and TLCOIVA after maximalexercise. Due to a possible accumulation of interstitial fluid,there is a suggestion of pulmonary suboedema involvement duringexercise in these patients.     

Early recovery of oxygen kinetics after submaximal exercise test predicts functional capacity in patients with chronic heart failure.

BACKGROUND: Oxygen (O2) uptake at peak exercise (VO2 peak) is an objective measurement of functional capacity in patients with chronic heart failure (CHF). The significance of recovery O2 kinetics parameters in predicting exercise capacity, and the parameters of submaximal exercise testing have not been thoroughly examined. METHODS AND RESULTS: Thirty-six patients (mean age = 48+/-14 years) with CHF and New York Heart Association functional class I, II, or III, and eight healthy volunteers (mean age = 39+/-13 years) were studied with maximal and submaximal cardiopulmonary exercise testing (CPET). The first degree slope of O2 uptake decay during early recovery from maximal (VO2/t-slope), and submaximal exercise (VO2/t-slope)(sub), were calculated, along with VO2 half-time (T(1/2)VO2). Patients with CHF had a longer recovery of O2 uptake after exercise than healthy volunteers, expressed by a lower VO2/t-slope (0.616+/-0.317 vs. 0.956+/-0.347 l min(-1) min(-1), P=0.029) and greater T(1/2)VO2 (1.28+/-0.30 vs. 1.05+/-0.15 min, P = 0.005). VO2/t-slope correlated with the VO2 peak (r = 0.84, P<0.001), anaerobic threshold (r = 0.79, P<0.001), and T(1/2)VO2, a previously established estimate of recovery O2 kinetics (r = -0.59, P<0.001). (VO2/t-slope)(sub) was highly correlated with VO2/t-slope after maximal exercise (r=0.87, P<0.001), with the VO2 peak (r=0.87, P<0.001) and with T(1/2)VO2 after maximal exercise (r=-0.62, P<0.001). VO2/t-slope after maximal and submaximal exercise was reduced in patients with severe exercise intolerance (F=9.3, P<0.001 and F=12.8, P<0.001, respectively). CONCLUSIONS: Early recovery O2 kinetics parameters after maximal and submaximal exercise correlate closely with established indices of exercise capacity in patients with CHF and in healthy volunteers. These findings support the use of early recovery O2 kinetics after submaximal exercise testing as an index of functional capacity in patients with CHF.     

Responses to constant work exercise in patients with chronic heart failure

OBJECTIVE—To describe the kinetics of metabolic gas exchange at the onset and offset of low level, constant work exercise in patients with chronic heart failure.
SETTING—Tertiary referral centre for cardiology.
PATIENTS—10 patients with chronic heart failure and 10 age matched controls.
METHODS—Each subject undertook maximum incremental exercise testing with metabolic gas exchange measurements, and a fixed load exercise test at 25 watts with metabolic gas exchange measurements before, during, and after the test. A monoexponential curve was fitted to the data to describe the kinetics of gas exchange at onset and offset of fixed load exercise.
OUTCOME MEASURES—Peak oxygen consumption; time constants of onset and offset for metabolic gas exchange variables during constant load exercise.
RESULTS—Peak oxygen consumption (mean (SD)) was higher in controls (26.1 (4.3) v 15.3 (5.3) ml/kg/min; p < 0.001) than in heart failure patients. Oxygen consumption during steady state was the same in both groups (9.2 (1.8) ml/kg/min in controls v 8.6 (1.6) in patients). The time constant of onset was the same in each group, but the time constant of offset was longer in patients (1.29 (0.14) v 0.82 (0.07); p < 0.005). There was a relation between peak oxygen consumption and time constant of offset (R = 0.56; p < 0.001).
CONCLUSIONS—The dynamics of gas exchange at the onset of low level exercise are normal in heart failure, but the recovery is delayed. The delay is related to the reduction in exercise capacity. A patient may spend a greater portion of the day recovering from exercise, and may not begin the next bout from a position of true recovery, perhaps contributing to the sensation of fatigue.


Keywords: chronic heart failure; metabolic gas exchange; constant load exercise     

心肺运动试验在慢性心力衰竭预后评估中的价值

心肺运动试验通过测定机体对运动的反应，可以评估包括心血管、肺、骨骼肌等多系统的功能和储备，显示出其独特的优势，特别是对于慢性心力衰竭患者的功能状态及预后能够进行客观定量的评估，具有极其重要的价值和意义。本文重点阐述心肺运动试验主要指标的意义及其在慢性心力衰竭预后评估中的价值。     

老年慢性左心衰竭与右心衰竭患者心肺运动试验特点比较

目的 比较老年慢性左心衰竭与右心衰竭患者心肺运动试验（CPET）特点。方法 入选老年非瓣膜性慢性左心衰竭患者25例[男性20例，年龄（60.2±4.7）岁]，以及年龄、性别、纽约心脏联合会（NYHA）心功能分级匹配的慢性右心衰竭患者25例[男性19例，年龄（61.3±5.7）岁]，排除合并肺部疾病、神经肌肉疾病或贫血等患者，对比其CPET特点。结果 两组患者年龄、性别、体质量指数（BMI）、NYHA心功能分级无明显差异，超声心动图左心室舒张末内径左心衰竭组明显大于右心衰竭组，分别为（66.1±9.0）和（40.4±5.4）mm，左心衰竭组左室射血分数明显低于右心衰竭组，分别为（32.5±11.9）%和（65.8±8.1）%（P＜0.001）。CPET结果显示，左心衰竭组峰值氧耗量（peak VO2）为（1056.6±340.5）ml/min，峰值单位千克体质量的氧耗量（peak VO2/kg）为（15.1±2.7）ml/（min·kg），peak VO2占预计值的百分比为（52±13）%，右心衰竭组分别为（750.9±269.1）ml/min，（11.0±3.2）ml/（min·kg）和（39±11）%，右心衰竭组较左心衰竭组明显降低（P＜0.05）。右心衰竭组峰值氧脉搏（VO2/HR）明显低于左心衰竭组[（6.3±2.2） vs （8.5±3.0）ml/（min·beat），P＝0.016]。右心衰竭组氧耗量与功率比值斜率（VO2/WR slope）明显低于左心衰竭组[（5.1±1.1） vs （6.4±1.8）ml/（min·W），P＝0.014]。与左心衰竭组相比，右心衰竭组每分通气量/每分二氧化碳生量成斜率（VE/VCO2 slope）明显升高[（34.7±8.2） vs （49.5±12.6），P＜0.001]。结论 与左心疾病所致左心衰竭患者相比，即使是相似的NYHA心功能分级，右心衰竭患者运动状态下的心肺功能更差，VE/VCO2 slope更高。     

运动锻炼为核心的家庭心脏康复项目对慢性心力衰竭患者康复治疗效果影响的临床研究

目的 探讨运动锻炼为核心的家庭心脏康复项目对慢性心力衰竭（chronic heart failure, CHF）患者心脏康复治疗效果的影响。方法 选择2015年1月至2019年1月间在北京康复医院临床诊断为CHF患者48 例,随机分为四组：对照组（12例）：进行除运动锻炼治疗之外的常规心脏康复指导;医院功率车组（12例）;家庭功率车组（12例）：患者分别在医院和家庭内进行功率车锻炼;家庭普通运动组（12例）：家庭内运动,运动方式可采用游泳、慢跑、快走、骑自行车等方式。三组运动组患者采用12周运动锻炼为核心的整体管理。治疗前、后分别评估患者运动心肺功能、心脏超声、6 min步行距离（6 minute walking distance, 6MWD）、Minnesota心力衰竭生活质量（quality of life, QoL）评分等。结果 12周康复治疗后,医院功率车组、家庭功率车组和家庭普通运动组患者峰值摄氧量［（19.5±4.4）ml·min-1·kg-1、（18.5±3.1）ml·min-1·kg-1、（17.0±1.9）ml·min-1·kg-1比（13.2±2.0）ml·min-1·kg-1,P<0.05］、左心室射血分数［（44.6±3.9）%、（44.3±8.7）%、（43.6±5.0）%比（37.8±5.7）%,P<0.05］和6MWD［（502.6±95.8）m、（482.1±54.5）m、（448.4±51.6）m比（383.5±77.1）m,P<0.05］均较对照组明显升高;同时QoL评分［14.8±7.9、12.9±6.8、19.1±8.7比43.2±10.8,P<0.05］均较对照组明显降低。组间比较显示,家庭普通运动组患者峰值摄氧量较医院功率车组降低（P<0.05）。治疗前后比较显示,12周康复管理后,医院、家庭功率车组和家庭普通运动组患者峰值摄氧量、左心室射血分数和6MWD均比治疗前升高（P<0.05）,QoL评分较治疗前降低（P<0.05）。结论 家庭运动康复为核心的整体管理,包括功率车和普通运动,可显著改善CHF患者心肺功能、运动耐力和生活质量,家庭康复作为心脏康复一种有效的治疗模式,值得大力推广。     

Physical responses to different modes of interval exercise in patients with chronic heart failure--application to exercise training

METHOD: In exercise training with chronic heart failure patients, workingmuscles should be stressed with high intensity stimuli withoutcausing cardiac overstraining. This is possible using intervalmethod exercise. In this study, three interval exercise modeswith different ratios of work/recovery phases (30/60 s, 15/60s and 10/60 s) and different work rates were compared duringcycle ergometer exercise in heart failure patients. Work ratefor the three interval modes was 50% (30/60 s), 70% (15/60 s)and 80% (10/60 s) of the maximum achieved during a steep ramptest (increments of 25 w/l0s) corresponding to 71, 98 and 111watts on average. Metabolic and cardiac responses to the threeinterval exercises were then examined including catecholaminelevels and perceived exertion. Parameters measured during intervalexercise were compared with an intensity level of 75% peak VO₂,determined during an ordinary ramp exercise test (incrementsof l2·5 W. min^–1). RESULTS: () (1) In all three interval modes, VO₂, ventilation and lactate did not increase significantlyduring the course of exercise. Mean values during the last workphase were between 754 ± 30 and 803 ± 46 ml. min^–1for VO₂, between 26 ± 3 and 28 ± 11. min^–1for ventilation and between 1·24 ±0·14and l·29 ± 0·10 mmol.1^–1 for lactate.(2) In mode 10/60 s, heart rate and systolic blood pressureincreased significantly (82 ± 485 ± 4 beats. min^–1;124 ± 5134 ± 5 mmHg; P<0·05 each), whilein mode 15/60 s catecholamines increased significantly (norepinephrine0·804 ± 0·0891·135 ± 0·094nmol. 1^–1; P<0·008; epinephrine 0·136± 0·012 0 193 ± 0·019 nmol. 1^–1;P<0·005). (3) In all three modes, rating of leg fatigueand dyspnoea increased significantly during exercise but remainedwithin the range of values considered ‘very light to fairlylight’ on the Borg scale. (4) Compared to an intensitylevel of 75% peak VO₂, work rate durrng interval work phaseswas between 143 and 221%, while cardiac stress (rate-pressureproduct) was significantly lower (83–88%). CONCLUSION: All three interval modes resulted in physical response in anacceptable range of values, and thus can be recommended.     

Response of the oxygen uptake efficiency slope to exercise training in patients with chronic heart failure

BACKGROUND: The oxygen uptake efficiency slope (OUES) is a new exercise parameter that provides prognostic power in patients with CHF. Little is known about the effects of exercise training (ET) on OUES. AIM: To describe the response of OUES to 6 months of ET in CHF patients and compare its evolution to that of other exercise variables. METHODS: 35 patients with CHF (NYHA II-III, age 54+/-9y, LVEF 31+/-10%) performed 3 maximal exercise tests, i.e. at the start, middle and end of a 6 month ET program. OUES, PeakVO(2), ventilatory anaerobic threshold (VAT) and slope VE/VCO(2) were determined. RESULTS: OUES, peakVO(2), VAT, slope VE/VCO(2), peak Watt, 6MWT and NYHA-class improved during the first part of the ET period (p<0.05). Only VAT, peak Watt and 6MWT continued to improve during the second part of the ET period (p<0.05) Improvements in OUES correlated better with improvements in peakVO(2) (r=0.77, p<0.001), than changes in other prognostic variables. DISCUSSION: OUES improves significantly after 6 months of ET. Changes in peakVO(2) correlate best with changes in OUES. OUES is sensitive to ET and can be used to evaluate the progression of exercise capacity in CHF patients.     

Prognostic value of changes over time in exercise capacity and echocardiographic measurements in patients with chronic heart failure.

AIMS: This study sought to examine the predictive values of changes over time in exercise capacity and echocardiographic measurements of ventricular dimensions or function in predicting mortality in patients with chronic heart failure. METHODS AND RESULTS: Sixty-two patients with chronic heart failure (58 men, mean [+/-SD] age 60+/-10 years, mean peak oxygen consumption (VO(2)) 18.2+/- 5.9 ml. kg(-1). min(-1), mean left ventricular ejection fraction 38.9+/-15. 8%) who underwent both treadmill exercise testing and echocardiographic examination on two occasions, separated by 19+/-15 months were followed-up for a mean of 17 months (interquartile range 9-30 months). During the follow-up period, 19 patients (30%) died and three (4.8%) underwent heart transplantation. Of measurements taken at a single time-point (visit 2) exercise duration, peak VO(2), ventilatory response to exercise (VE/VCO(2)), left atrial diameter and left ventricular ejection fraction were found, by Cox proportional-hazard analysis, to predict the outcome in these patients (all P<0.05). Of the changes in parameters between visit 1 to visit 2, only changes in peak VO(2)per year (P=0.026) predicted non-transplanted survival (independent of changes in left ventricular ejection fraction and VE/VCO(2)). In Kaplan-Meier survival analysis patients with increased peak VO(2)over time (n=28) showed a better prognosis at 2 years (cumulative survival 75% [95% confidence interval: 56-95%] than those with a decrease in peak VO(2)(n=34, cumulative survival 50% [95% confidence interval: 31-68%]). CONCLUSIONS: Although single estimates of peak VO(2), VE/VCO(2)and left ventricular ejection fraction have significant prognostic importance in patients with chronic heart failure, when monitoring changes over time only peak VO(2)remains a significant predictor of outcome.     

Cardiopulmonary exercise testing for prognosis in chronic heart failure: continuous and independent prognostic value from VE/VCO(2)slope and peak VO(2).

BACKGROUND: Chronic heart failure carries a poor prognosis. Cardiopulmonary exercise testing is useful in predicting survival. We set out to establish the prognostic value of peak VO(2)and VE/VCO(2)slope across a range of threshold values. METHOD AND RESULTS: Three hundred and three consecutive patients with stable chronic heart failure underwent cardiopulmonary exercise testing between 1992 and 1996. Their age was 59+/-11 years (mean+/-SD), peak VO(2)17. 8+/- 6.6 ml. kg(-1)min(-1), VE/VCO(2)slope 37+/-12. At the end of follow-up in January 1999, 91 patients had died (after a median of 7 months, interquartile range 3-16 months). The median follow-up for the survivors was 47 months (interquartile range 37-57 months). The areas under the receiver-operating characteristic curves for predicting mortality at 2 years were 0.77 for both peak VO(2)and VE/VCO(2)slope. With peak VO(2)and VE/VCO(2)slope viewed as continuous variables in the Cox proportional-hazards model, they were both highly significant prognostic indicators, both in univariate analysis and bivariate analysis (P<0.001 for VE/VCO(2)slope, P<0.003 for peak VO(2)). CONCLUSIONS: Lower peak VO(2)implies poorer prognosis across a range of values from 10 to 20 ml. kg(-1)min(-1), without a unique threshold. Gradations of elevation of the VE/VCO(2)slope also carry prognostic information over a wide range (30-55). The two parameters are comparable in terms of prognostic power, and contribute complementary prognostic information.     

Effects of home-based exercise training on neurovascular control in patients with heart failure

BACKGROUND: The effect of home-based exercise training on neurovascular control in heart failure patients is unknown. AIMS: To test the hypothesis that home-based training would maintain the reduction in muscle sympathetic nerve activity (MSNA) and forearm vascular resistance (FVR) acquired after supervised training. METHODS AND RESULTS: Twenty-nine patients (54+/-1.9 years, EF<40%) were randomised into two groups: untrained control (n=12) and exercise trained (n=17). Both groups underwent assessment of Quality of Life (QoL), MSNA, and forearm blood flow. The exercise group underwent a 4-month supervised training program followed by 4 months of home-based training. After the initial 4 months of training, patients in the exercise group showed a significant increase in peak VO(2) and reduction in MSNA, compared to the untrained group, but this was not maintained during 4 months of home-based training. In contrast, the decrease in FVR (56+/-3 vs. 46+/-4 vs. 40+/-2 U, p=0.008) and the improvement in QOL that were achieved during supervised training were maintained during home-based training. CONCLUSIONS: Home-based training following supervised training is a safe strategy to maintain improvements in QoL and reduction in FVR in chronic heart failure patients, but is an inadequate strategy to maintain fitness as estimated by peak VO(2) or reduction in neurohumoral activation.     

Ventilatory capacity and exercise tolerance in patients with chronic stable heart failure

BACKGROUND: Patients with chronic heart failure complain of breathlessness. This is associated with an increase in the ventilatory response to carbon dioxide production (VE/VCO(2) slope), yet a reduction in the maximal ventilation achieved at peak exercise. We analysed ventilatory capacity in heart failure in relation to exercise capacity. METHODS: We analysed data from 74 patients with chronic stable heart failure [age (S.D.) 50.6 (8.8) years; left ventricular ejection fraction 30 (15)%] and 36 controls [48.9 (11.5) years]. Subjects undertook maximal incremental exercise testing with metabolic gas exchange measurements to derive peak oxygen consumption (VO(2)), the VE/VCO(2) slope and ventilation. Spirometry was used to measure FEV(1) and FVC. Maximal voluntary ventilation (MVV) was calculated as FEV(1)x 35. RESULTS: Peak VO(2) was lower in patients [20.9 (7.5) ml min(-1) kg(-1) vs. 34.5 (10.1); P<0.001] and VE/VCO(2) greater [33.4 (10.7) vs. 26.0 (4.7); P<0.001]. Ventilation at peak exercise was lower in patients [63.5 (20.4) l/min vs. 86.9 (29.5); P<0.001], as was MVV [110.1 (37.9) l/min vs. 136.2 (53.1); P<0.001], but ventilation at peak as a proportion of MVV was the same in patients [60.0 (19.0)%] as controls [65.7 (12.4)%)]. There was an inverse relation between peak VO(2) and VE/VCO(2) slope (r=-0. 62; P<0.001). Percentage predicted FEV(1) correlated with ventilation at peak (r=0.62; P<0.001) and inversely with VE/VCO(2) slope (r=-0.32; P<0.001). There was no relation between percentage of MVV achieved and peak VO(2), or VE/VCO(2) slope. CONCLUSIONS: Although ventilation at peak exercise is lower in patients with heart failure than normal subjects, ventilation is the same proportion of maximal voluntary ventilation. These findings suggest that ventilatory capacity does not limit exercise capacity in heart failure.     

运动康复训练对老年慢性心力衰竭患者预后的影响

目的探讨运动康复训练对老年慢性心力衰竭患者预后的影响。方法65例老年慢性心衰患者随机分为干预组33例和对照组32例。对照组给予常规治疗,干预组在常规治疗基础上采用运动康复训练,疗程均为8周。结果治疗8周后,干预组较对照组左室射血分数增加、NYHA心功能改善、6 min步行距离延长（P均〈0.05）;随访12个月后干预组较对照组生活质量明显提高（P〈0.05）,因心衰再入院率降低（P〈0.05）;干预组患者康复训练中未发生心衰加重、恶性心律失常等不良事件。结论对老年慢性心力衰竭患者实施运动康复训练安全有效。     

Excessive ventilation during early phase of exercise: a new predictor of poor long-term outcome in patients with chronic heart failure

BACKGROUND: Studies demonstrating prognostic value of excessive exercise ventilation in chronic heart failure (CHF) have focused on data derived from the whole cardiopulmonary exercise test (CPET). Whether ventilatory response to early phase of exercise is useful for risk stratification in CHF is unknown. METHODS AND RESULTS: We evaluated 216 patients with systolic CHF who underwent CPET (age: 60+/-11 years, NYHA class [I/II/III/IV]: 18/104/77/17). Ventilatory response to exercise (slope of regression line relating ventilation to carbon dioxide production) was calculated from the whole exercise test (VE-VCO(2)-all) and from the first 3 min of exercise (early phase - VE-VCO(2)-3 min). During follow-up (mean: 40+/-20 months, >3 years in survivors), 89 (41%) CHF patients died. High VE-VCO(2)-all and VE-VCO(2)-3 min predicted poor outcome in single predictor analyses, and in multivariable models when adjusted for prognosticators (age, NYHA class, ejection fraction, peak VO(2)) (P<0.0001). In receiver operating characteristic curve analysis, areas under curve for 3-year follow-up were similar for VE-VCO(2)-all and VE-VCO(2)-3 min. VE-VCO(2)-3 min maintained its prognostic value in patients taking beta-blockers (P<0.0001) and those unable to perform maximal CPET (P=0.0009). CONCLUSIONS: In CHF patients, excessive ventilation assessed over the first 3 min predicts poor outcome. Assessment of ventilatory response to exercise for prognostic stratification may be extended to patients unable to perform maximal CPET.     

Chronic heart failure in the elderly: value of cardiopulmonary exercise testing in risk stratification

OBJECTIVE: To assess the value of cardiopulmonary exercise testing in predicting prognosis in a cohort of elderly patients with chronic heart failure (CHF). DESIGN: A retrospective cohort study of all patients with CHF over the age of 70 years assessed between January 1992 and May 1997. SETTING: Tertiary centre. PATIENTS: 50 patients (mean (SD) age 75.9 (4.5) years, 8 women) with CHF New York Heart Association (NYHA) class I (3 patients), II (25 patients), III (20 patients), and IV (2 patients). Follow up was complete for two years in all patients. RESULTS: The patients underwent cardiopulmonary exercise testing (peak oxygen consumption 15.2 (4.5) ml/kg/min, minute ventilation/carbon dioxide production (VE/VCO(2)) slope 38.7 (11.8)); radionucleide ventriculography (left ventricular ejection fraction 32.8 (14.3)%); serum sodium measurement (139 (2.8) mmol/l); and echocardiography (left ventricular end diastolic dimension 6.1 (1.1) cm, left ventricular end systolic dimension 4.7 (1.5) cm). At the end of follow up in May 1999, 26 patients had died. The median follow up of the survivors was 47.7 months (interquartile range 31. 5-53.5 months). On univariate analysis VE/VCO(2) slope (p < 0.0001), NYHA class (p < 0.001), peak oxygen uptake (VO(2)) (p < 0.01), left ventricular end systolic dimension (p < 0.05), and serum sodium concentration (p < 0.05) had significant predictive power. Stepwise multivariate analysis identified only VE/VCO(2) slope (p < 0.01), NYHA class (p < 0.05), and peak VO(2) (p< 0.05) as conveying significant independent prognostic information. CONCLUSION: Elderly patients with CHF have a high mortality, with the majority dead within two years. Cardiopulmonary exercise testing provides important information for risk stratification within this group and its use should not be neglected.     

Iron deficiency predicts impaired exercise capacity in patients with systolic chronic heart failure

Background

Iron is an indispensable element of hemoglobin, myoglobin, and cytochromes, and, beyond erythropoiesis, is involved in oxidative metabolism and cellular energetics. Hence, iron deficiency (ID) is anticipated to limit exercise capacity. We investigated whether ID predicted exercise intolerance in patients with systolic chronic heart failure (CHF).

Methods and Results

We prospectively studied 443 patients with stable systolic CHF (age 54 ± 10 years, males 90%, ejection fraction 26 ± 7%, New York Heart Association Class I/II/III/IV 49/188/180/26). ID was defined as: serum ferritin <100 μg/L or serum ferritin 100–300 μg/L with serum transferrin saturation <20%. Exercise capacity was expressed as peak oxygen consumption (VO₂) and ventilatory response to exercise (VE-VCO₂ slope). ID was present in 35 ± 4% (±95% confidence interval) of patients with systolic CHF. Those with ID had reduced peak VO₂ and increased VE-VCO₂ slope as compared to subjects without ID (peak VO₂: 13.3 ± 4.0 versus 15.3 ± 4.5 mL•min•kg, VE-VCO₂ slope: 50.9 ± 15.8 versus 43.1 ± 11.1, respectively, both P < .001, P < .05). In multivariable models, the presence of ID was associated with reduced peak VO₂ (β = −0.14, P < .01 P < .05) and higher VE-VCO₂ slope (β = 0.14, P < .01 P < .05), adjusted for demographics and clinical variables. Analogous associations were found between serum ferritin, and both peak VO₂ and VE-VCO₂ slope (P < .05).

Conclusions

ID independently predicts exercise intolerance in patients with systolic CHF, but the strength of these associations is relatively weak. Whether iron supplementation would improve exercise capacity in iron-deficient subjects requires further studies.     

Predictors of exercise capacity in chronic heart failure

Abnormalities of skeletal muscle rather than of haemodynamicsmay be important determinants of exercise capacity in chronicheart failure. We investigated an array of indicators of centralhaemodynamics and peripheral muscle function to establish whichresting measurements predicted exercise performance. In 20 patients quadriceps strength, resting and peak leg bloodflow and leg muscle cross sectional area were measured. In 18patients average daytime blood pressure and pulse rate, haemodynamicvariables at rest and during exercise, and autonomic activitywere measured. There were correlations between peak oxygen consumptionand quadriceps strength (0.65; P=0.007), thigh muscle crosssectional area (r=0.63; P=0.004), and average daytime systolicblood pressure (r=0.66; P<0.01). There were no correlationswith indices of peripheral blood flow, measures of haemodynamicfunction, or autonomic function. Quadriceps strength was themost important individual correlate of exercise tolerance (r=0.73).With total muscle cross sectional area and left quadriceps strengthalso taken into consideration, 82% of the variation in peakoxygen consumption was explained. Of the haemodynamic variables,only average daytime systolic blood pressure predicted exerciseperformance. The resting variables that best predict exercise performancein chronic heart failure are measures of skeletal muscle functionand bulk, and average daytime systolic blood pressure. Thesefindings suggest that abnormalities in the periphery largelydetermine exercise performance in chronic heart failure, andthat the ability of the heart to generate an adequate bloodpressure response to daily activities is also predictive offunctional status.     

Early heart rate recovery after exercise predicts mortality in patients with chronic heart failure

BACKGROUND: Patients with chronic heart failure (CHF) have multiple abnormalities of autonomic regulation that have been associated to their high mortality rate. Heart rate recovery immediately after exercise is an index of parasympathetic activity, but its prognostic role in CHF patients has not been determined yet. METHODS: Ninety-two stable CHF patients (83M/9F, mean age: 51+/-12 years) performed an incremental symptom-limited cardiopulmonary exercise testing. Measurements included peak O2 uptake (VO2p), ventilatory response to exercise (VE/VCO2 slope), the first-degree slope of VO2 for the 1st minute of recovery (VO2/t-slope), heart rate recovery [(HRR1, bpm): HR difference from peak to 1 min after exercise] and chronotropic response to exercise [%chronotropic reserve (CR, %)=(peak HR-resting HR/220-age-resting HR)x100]. Left ventricular ejection fraction (LVEF, %) was also measured by radionuclide ventriculography. RESULTS: Fatal events occurred in 24 patients (26%) during 21+/-6 months of follow-up. HRR1 was lower in non-survivors (11.4+/-6.4 vs. 20.4+/-8.1; p<0.001). All cause-mortality rate was 65% in patients with HRR112 bpm (log-rank: 32.6; p<0.001). By multivariate survival analysis, HRR1 resulted as an independent predictor of mortality (chi2=19.2; odds ratio: 0.87; p<0.001) after adjustment for LVEF, VO2p, VE/VCO2 slope, CR and VO2/t-slope. In a subgroup of patients with intermediate exercise capacity (VO2p: 10-18, ml/kg/min), HRR1 was a strong predictor of mortality (chi2: 14.3; odds ratio: 0.8; p<0.001). CONCLUSIONS: Early heart rate recovery is an independent prognostic risk indicator in CHF patients and could be used in CHF risk stratification.