LA CONSULTA SEMANAL

ENERO 2001

CONSULTA

Am Heart J 1999 Aug;138(2 Pt 1):291-8 [Texto completo con registro libre a www.medscape.com]
A shuttle walk test for assessment of functional capacity in chronic heart failure.
Morales FJ, Martinez A, Mendez M, Agarrado A, Ortega F, Fernandez-Guerra J, Montemayor T, Burgos J
Department of Cardiology, Virgen del Rocio University Hospital, Cadiz, Spain.
BACKGROUND: Peak oxygen uptake (peak VO(2)) is a reference parameter in the assessment of functional capacity of patients with chronic heart failure, but the procedure for cardiopulmonary exercise testing with expired gas analysis is complex and expensive, so more simple and available methods are desirable. METHODS: We compared the usefulness of a time-limited walk test, the 6-minute walk test (6-MT), with that of a symptom-limited walk test, the shuttle walk test (SWT), in the evaluation of patients with moderate to severe chronic heart failure. We prospectively studied 46 clinically stable patients in New York Heart Association class II to IV heart failure with left ventricular ejection fraction <40% (aged 53 +/- 10 years, ejection fraction 23% +/- 8%, New York Heart Association functional class 2.8 +/- 0.7). Each patient performed two 6-MT, two SWT and a cardiopulmonary exercise testing within 2 weeks. RESULTS: We found a close correlation between distance walked in SWT and peak VO(2 ) (r = 0.83, P <.001) and a moderate correlation between distance in 6-MT and peak VO(2) (r = 0.69, P <.001). Both walk tests showed to be reproducible after just one practice walk. All patients who walked > 450 m in SWT had a peak VO(2) >14 mL/kg/min. The overall discriminatory accuracy for SWT distance was greater than that for 6-MT distance for predicting a peak VO(2 ) <14 mL/kg/min (area under receiver operator characteristic curves 0.97 and 0.83 respectively, P =.02). Stepwise multivariate regression analysis, including clinical, exercise testing, echocardiographic, radionuclide-angiographic, and rest hemodynamic data, showed that distance walked in SWT was the only independent predictor of peak VO(2) (P <.001) and the strongest predictor of percent achieved of age- and sex-predicted peak VO(2) (%PVO(2)) (P <.001), with only age offering additional information (P =.02). CONCLUSIONS: The SWT shows to be a feasible and safe method to evaluate patients with chronic heart failure that strongly and independently predicts peak VO(2) and %PVO(2.) This symptom-limited walk test seems to be more useful than 6-MT in the assessment of functional capacity in these patients. 
Publication Types:
  Clinical trial


Am Heart J 1998 Sep;136(3):449-57 [Texto completo con registro libre en www.medscape.com]
Does the 6-minute walk test predict the prognosis in patients with NYHA class II or III chronic heart failure?
Roul G, Germain P, Bareiss P
Cardiology Department, Hopitaux Universitaires de Strasbourg, Hopital de Hautepierre, France.
BACKGROUND: We prospectively evaluated the potential of the 6-minute walk test compared with peak VO2 in predicting outcome of patients with New York Heart Association (NYHA) class II or III heart failure. METHODS AND RESULTS: Patients with a history of heart failure caused by systolic dysfunction were included. The combined final outcome (death or hospitalization for heart failure) was used as the judgment criterion. One hundred twenty-one patients (age 59+/-11 years; left ventricular ejection fraction 29.6%+/-13%) were included and followed for 1.53+/-0.98 years. Patients were separated into two groups according to outcome: group 1 (G1, 74 patients), without events, and group 2 (G2, 47 patients), who reached the combined end point. Peak VO2 was clearly different between G1 and G2 (18.5+/-4 vs. 13.9+/-4 ml/kg/min, p=0.0001) but not the distance walked (448+/-92 vs 410+/-126 m; p=0.084, not significant). Survival analysis showed that unlike peak VO2, the distance covered was barely distinguishable between the groups (p < 0.08). However, receiver operating characteristic curves revealed that the best performances for the 6-minute walk test were obtained for subjects walking < or =300 m. These patients had a worse prognosis than those walking farther (p=0.013). In this subset of patients, there was a significant correlation between distance covered and peak VO2 (r=0.65, p=0.011). Thus it appears that the more severely affected patients have a daily activity level relatively close to their maximal exercise capacity. Nevertheless, the 300 m threshold suggested by this study needs to be validated in an independent population. CONCLUSIONS: A distance walked in 6 minutes < or =300 m can predict outcome. Moreover, in these cases there is a significant correlation between the 6-minute walk test and peak VO2 demonstrating the potential of this simple procedure as a first-line screening test for this subset of patients.
Comments:
  Comment in: Am Heart J 1998 Sep;136(3):371-2


Ann Intern Med 1998 Aug 15;129(4):286-93 [Texto completo libre]
Clinical, hemodynamic, and cardiopulmonary exercise test determinants of survival in patients referred for evaluation of heart failure.
Myers J, Gullestad L, Vagelos R, Do D, Bellin D, Ross H, Fowler MB
Palo Alto Veterans Affairs Health Care System, California 94304, USA.
BACKGROUND: Accurate prognosis in chronic heart failure has become increasingly important in assessing the efficacy of treatment and in appropriately allocating scarce resources for transplantation. Previous studies of severe heart failure have been limited by short follow-up periods and few deaths. OBJECTIVE: To establish clinical, hemodynamic, and cardiopulmonary exercise test determinants of survival in patients with heart failure. DESIGN: Retrospective study. SETTING: Hospital-based outpatient heart failure clinic. PARTICIPANTS: 644 patients referred for evaluation of heart failure over 10 years. MEASUREMENTS: Age, cause of heart failure, body surface area, cardiac index, ejection fraction, pulmonary capillary wedge pressure, left ventricular dimensions, watts achieved during exercise, heart rate, maximum systolic blood pressure, and oxygen uptake (VO2) at the ventilatory threshold and at peak exercise were measured at baseline. Univariate and multivariate analyses were done for clinical, hemodynamic, and exercise test predictors of death. A Cox hazards model was developed for time of death. RESULTS: During a mean follow-up period of 4 years, 187 patients (29%) died and 101 underwent transplantation. Actuarial 1-year and 5-year survival rates were 90.5% and 73.4%, respectively. Resting systolic blood pressure, watts achieved, peak VO2, VO2 at the ventilatory threshold, and peak heart rate were greater among survivors than among nonsurvivors. Cause of heart failure (coronary artery disease or cardiomyopathy) was a strong determinant of death (relative risk for coronary artery disease, 1.73; P< 0.01). By multivariate analysis, only peak VO2 was a significant predictor of death. Stratification of peak VO2 above and below 12, 14, and 16 mL/kg per minute demonstrated significant differences in risk for death, but each cut-point predicted risk to a similar degree. CONCLUSIONS: Peak VO2 outperforms clinical variables, right-heart catheterization data, exercise time, and other exercise test variables in predicting outcome in severe chronic heart failure. Direct measurement of VO2 should be included when clinical or surgical decisions are being made in patients referred for evaluation of heart failure or those considered for transplantation.


J Am Coll Cardiol 1997 Mar 1;29(3):597-603
Exercise training in patients with severe congestive heart failure: enhancing peak aerobic capacity while minimizing the increase in ventricular wall stress.
Demopoulos L, Bijou R, Fergus I, Jones M, Strom J, LeJemtel TH
Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
OBJECTIVES: The aims of the study were to 1) assess the effects of 12 weeks of exercise training at low work loads (i.e., corresponding to < or = 50% of peak oxygen consumption [Vo2]) on peak Vo2 and hyperemic calf blood flow in patients with severe congestive heart failure; and 2) evaluate left ventricular diastolic pressure and wall stress during exercise performed at work loads corresponding to < or = 50% and 70% to 80% of peak Vo2. BACKGROUND: Whether the benefits of exercise training can be achieved at work loads that result in lower left ventricular diastolic wall stress than those associated with conventional work loads is unknown in patients with severe congestive heart failure. METHODS: Sixteen patients with severe congestive heart failure trained at low work loads for 1 h/day, four times a week, for 12 weeks. Peak Vo2 and calf and forearm reactive hyperemia were measured before and during training. Nine of the 16 patients underwent right heart catheterization and echocardiography during bicycle exercise at low and conventional work loads (i.e., 50% and 70% to 80% of peak Vo2, respectively). RESULTS: The increase in left ventricular diastolic wall stress was substantially lower during exercise at low work loads than during exercise at conventional work loads, (i.e., [mean +/- SEM] 23.3 +/- 7.4 vs. 69.6 +/- 8.1 dynes/cm2 (p < 0.001). After 6 and 12 weeks of training, peak Vo2 increased from 11.5 +/- 0.4 to 14.0 +/- 0.5 and 15.0 +/- 0.5 ml/kg per min, respectively (p < 0.0001 vs. baseline for both). Peak reactive hyperemia significantly increased in the calf but not in the forearm. The increases in peak Vo2 and calf peak reactive hyperemia correlated closely (r = 0.61, p < 0.02). CONCLUSIONS: In patients with severe congestive heart failure, peak Vo2 is enhanced by exercise training at work loads that result in smaller increases in left ventricular diastolic wall stress than those observed at conventional work loads.


Am Heart J 1997 Apr;133(4):447-53
Effects of exercise training and activity restriction on 6-minute walking test performance in patients with chronic heart failure.
Meyer K, Schwaibold M, Westbrook S, Beneke R, Hajric R, Lehmann M, Roskamm H
Herz-Zentrum, Bad Krozingen, Freie Universitat Berlin, Germany.
Eighteen hospitalized patients with severe chronic heart failure (ejection fraction [mean +/- SEM] 21% +/- 1%) underwent 3 weeks of exercise training (interval bicycle ergometer and treadmill walking training exercises) and 3 weeks of activity restriction in a random-order crossover trial. Before and after exercise training and after activity restriction, a 6-minute walking test was performed to determine the maximum distance walked, hemodynamic and cardiopulmonary responses, norepinephrine levels, and ratings of leg fatigue and dyspnea while walking. A ramp test on bicycle ergometer (increments of 12.5 W/min) was performed before and after exercise training and activity restriction to determine peak oxygen uptake. After training, the maximum distance walked was increased by 65% (from 232 +/- 21 m at baseline to 382 +/- 20 m; p < 0.001), whereas after activity restriction (253 +/- 19 m) there was no significant difference compared with baseline. No significant differences in hemodynamic and cardiopulmonary parameters (with the exception of the ventilatory equivalent for carbon dioxide and perceived exertion) or norepinephrine levels were observed during walking tests. Improvement in maximum distance walked correlated significantly with training-induced increase in peak oxygen uptake measured during bicycle ergometry (r = 0.47, p < 0.05). The lower the maximum distance walked at baseline, the more pronounced the training-induced prolongation of maximum distance (r= -0.73; p < 0.001). These data support the value of exercise training in patients with severe chronic heart failure for improving maximum distance walked, as documented by the 6-minute walking test. The impairment of walking test performance during activity restriction suggests a need for long-term exercise training programs.
Publication Types:
  Clinical trial
  Randomized controlled trial


Chest 1997 Apr;111(4):1146
Assessment of oxygen uptake during the six-minute walk test in patients with heart failure.
Faggiano P, D'Aloia A, Gualeni A, Giordano A
Publication Types:
  Comment
  Letter
Comments:
  Comment on: Chest 1996 Aug;110(2):325-32
  Comment in: Chest 1997 May;111(5):1465-6


Am Heart J 1997 Aug;134(2 Pt 1):203-6 [Texto completo con registro libre en www.medscape.com]
Assessment of oxygen uptake during the 6-minute walking test in patients with heart failure: preliminary experience with a portable device.
Faggiano P, D'Aloia A, Gualeni A, Lavatelli A, Giordano A
Cardiology Division, Salvotore Maugeri Foundation, IRCCS, Gussago, Brescia, Italy.
In patients with heart failure, the 6-minute walking test (6-MWT) is considered a useful measure of submaximal exercise capacity. Few data are available on oxygen uptake (VO2) during a standard 6-MWT. The aim of this study was to measure the 6-MWT VO2 by using a recently validated portable instrument in 26 patients (24 men, 2 women; mean age, 56 +/- 11 years) with mild to severe heart failure (New York Heart Association class II, 10 patients; III, 10 patients; IV, 6 patients; left ventricular ejection fraction: 22 +/- 6%). Peak VO2 was measured during a symptom-limited cardiopulmonary exercise test performed in a period of 1 to 3 days (10 watt/m increment). Peak VO2 was 15 +/- 4 ml/kg/m during the symptom-limited test and 12.9 +/- 4.4 ml/kg/m during the 6-MWT (p < 0.05), corresponding to 86% of peak VO2. Seven (27%) of 26 patients showed a 6-MWT VO2 equal to or higher than peak VO2. Anaerobic threshold (AT) was identified in 23 of 26 patients during maximal exercise and in 19 of 26 patients during the 6-MWT; VO2 at AT was similar in the two tests (12.2 +/- 3.5 ml/kg/m vs 11.9 +/- 4.2 ml/kg/m). The distance walked during the 6-MWT (mean, 418 +/- 20 m) significantly correlated with 6-MWT VO2 (r = 0.71) and peak VO2 (r = 0.63); the 6-MWT VO2 also showed a high correlation with peak VO2 (r = 0.86). Thus in patients with failing hearts, VO2 during 6-MWT (considered a classic submaximal exercise) is, on average, only 15% lower than peak VO2 and is largely supported by anaerobic metabolism (work above the anaerobic threshold).


Chest 1996 Aug;110(2):325-32
The six-minute walk test predicts peak oxygen uptake and survival in patients with advanced heart failure.
Cahalin LP, Mathier MA, Semigran MJ, Dec GW, DiSalvo TG
Massachusetts General Hospital Physical Therapy Services, Boston 02114, USA.
BACKGROUND: The 6-min walk test (6'WT) is a simple measure of functional capacity and predicts survival in patients with moderate heart failure (HF). METHODS: To assess the role of the 6'WT in the evaluation of patients with advanced HF, 45 patients (age 49 +/- 8 years, mean +/- SD; New York Heart Association class 3.3 +/- 0.6; left ventricular ejection fraction 0.20 +/- 0.06; right ventricular ejection fraction 0.31 +/- 0.11) underwent symptom-limited cardiopulmonary exercise testing and the 6'WT during cardiac transplant evaluation. RESULTS: Mean 6'WT distance ambulated was 310 +/- 100 m and peak oxygen uptake (peak Vo2) was 12.2 +/- 4.5 mL/kg/min. There was a significant correlation between 6'WT distance ambulated and peak Vo2 (r = 0.64, p < 0.001). Multivariate analysis of patient characteristics, resting hemodynamics, and 6'WT results identified the distance ambulated during the 6'WT as the strongest predictor of peak Vo2 (p < 0.001). 6'WT distance ambulated less than 300 m predicted an increased likelihood of death or pretransplant hospital admission for continuous inotropic or mechanical support within 6 months (p = 0.04), but did not predict long-term overall or event-free survival with a mean follow-up of 62 weeks. Peak Vo2 was the best predictor of long-term overall and event-free survival. CONCLUSIONS: In patients with advanced HF evaluated for cardiac transplantation, distance ambulated during the 6'WT predicts (1) peak Vo2 and (2) short-term event-free survival.
Comments:
  Comment in: Chest 1996 Aug;110(2):310-2
  Comment in: Chest 1997 Apr;111(4):1146
  Comment in: Chest 1997 Jul;112(1):289-90


JAMA 1993 Oct 13;270(14):1702-7
Prediction of mortality and morbidity with a 6-minute walk test in patients with left ventricular dysfunction. SOLVD Investigators.
Bittner V, Weiner DH, Yusuf S, Rogers WJ, McIntyre KM, Bangdiwala SI, Kronenberg MW, Kostis JB, Kohn RM, Guillotte M, et al
Department of Medicine, University of Alabama at Birmingham 35294.
OBJECTIVE--To study the potential usefulness of the 6-minute walk test, a self-paced submaximal exercise test, as a prognostic indicator in patients with left ventricular dysfunction. DESIGN--Data were collected during a prospective cohort study, the Studies of Left Ventricular Dysfunction (SOLVD) Registry Substudy. SETTING--Twenty tertiary care hospitals in the United States, Canada, and Belgium. PARTICIPANTS--A stratified random sample of 898 patients from the SOLVD Registry who had either radiological evidence of congestive heart failure and/or an ejection fraction of 0.45 or less were enrolled in the substudy and underwent a detailed clinical evaluation including a 6-minute walk test. Patients were followed up for a mean of 242 days. OUTCOME MEASURES--Mortality and hospitalization. RESULTS--During follow-up, 52 walk-test participants (6.2%) died and 252 (30.3%) were hospitalized. Hospitalization for congestive heart failure occurred in 78 participants (9.4%), and the combined endpoint of death or hospitalization for congestive heart failure occurred in 114 walk-test participants (13.7%). Compared with the highest performance level, patients in the lowest performance level had a significantly greater chance of dying (10.23% vs 2.99%; P = .01), of being hospitalized (40.91% vs 19.90%; P = .002), and of being hospitalized for heart failure (22.16% vs 1.99%; P < .0001). In a logistic regression model, ejection fraction and distance walked were equally strong and independent predictors of mortality and heart failure hospitalization rates during follow-up. CONCLUSION--The 6-minute walk test is a safe and simple clinical tool that strongly and independently predicts morbidity and mortality in patients with left ventricular dysfunction.
Comments:
Comment in: JAMA 1994 Mar 2;271(9):661-2


Eur Heart J 1992 Jun;13(6):789-93
Oxygen consumption during corridor walk testing in chronic cardiac failure.
Riley M, McParland J, Stanford CF, Nicholls DP
Royal Victoria Hospital, Belfast, N. Ireland.
We have examined the use of a 6-min corridor walk test in the assessment of  functional capacity in 16 patients with chronic cardiac failure. VO2 was determined concurrently by a portable 'Oxylog'. Three tests were performed sequentially, and although there was a significant increase in distance walked and highest VO2 achieved between the first and second tests, good reproducibility was attained between the second and third tests. Both walk test variables correlated well with previously determined peak achieved VO2, and NYHA classes were separated adequately. Corridor walk testing, with or without measurement of VO2 should be a useful adjunct to maximal exercise testing in interventional studies.