Peak Oxygen Uptake Better Predicts Outcome Than Submaximal Respiratory Data in Heart Transplant Candidates

Abstract

Background-Many studies have focused on the prognostic power of peak oxygen uptake (V O 2 ) in patients with chronic heart failure, but maximal exercise testing is not without risk. The purpose of the present study was, therefore, to assess the prognostic significance of the steepness of changes in ventilation and carbon dioxide output (V CO 2 ) during submaximal exercise in comparison with V O 2 . Methods and Results-The study population consisted of 284 adult heart transplant candidates who performed a graded maximal bicycle ergometer test with respiratory gas analysis. Using the respiratory data up to a gas exchange ratio of 1.0, 3 submaximal slopes were calculated in each patient. During follow-up (median, 1.33 years), 57 patients died and 149 had Ն1 cardiovascular event. When using Cox proportional hazards analysis, both peak V O 2 and submaximal respiratory slopes predicted outcome before and after accounting for age, sex, and body mass index. However, whereas the prognostic power of peak V O 2 was independent of submaximal respiratory data, the prognostic significance of the slopes was lost after controlling for peak V O 2 . Stepwise regression analysis even selected peak V O 2 as an independent prognostic index among the following factors: cause of heart failure, ejection fraction, pulmonary vascular resistance, natremia, and the forced expiratory volume in 1 s. Conclusions-Respiratory data during submaximal exercise are significant predictors of outcome in patients with chronic heart failure, but their prognostic power is inferior to that of peak V O 2 . However, these data may be useful when maximal exercise is contraindicated or not achievable.

Neurohormonal Determinants of Peak Oxygen Uptake in Patients with Chronic Heart Failure

“…Previous studies have showed that peak oxygen uptake (VO 2 ) obtained at maximal exercise provides not only an objective measure of functional capacity, but also prognostic information in patients with CHF. [9][10][11][12][13][14] We predict that patients with exercise intolerance are those with higher neurohormonal and cytokine activation, however, the relation between peak VO 2 and multiple neurohormone/cytokine levels has not been clearly elucidated. Thus, we conducted the present study to clarify the relation between neurohormonal/cytokine activation and functional capacity as measured by cardiopulmonary exercise testing in patients with mild to moderate CHF.…”

Comparison of the Seattle Heart Failure Model and Cardiopulmonary Exercise Capacity for Prediction of Death in Patients With Chronic Ischemic Heart Failure and Intracoronary Progenitor Cell Application

“…There is ongoing debate whether submaximal CPET results are prognostically useful. 9,24 Even if the subgroup of patients with reduced exercise tolerance could have generated submaximal peak VO 2 values, they do reproduce valid VE/VCO 2 slopes. 8 We therefore did not exclude patients with short-lasting, possibly submaximal, exercise tests.…”

Is the predictive power of a low-pulse pressure independent of peak oxygen uptake in advanced chronic heart failure?

“…[1][2][3][4] By contrast, recent studies have shown that a low PP carries a worse prognosis in patients with advanced chronic heart failure (CHF) 5,6 and decompensated heart failure, 7 which is attributed to the fact that the impaired LV function has become the major determinant of PP. However, peak oxygen uptake (VO 2 peak), which is a major if not the major prognostic factor in CHF 8,9 was not considered in these studies. Our aim was therefore to analyse whether PP adds prognostic precision to VO 2 peak in patients with advanced CHF, who were referred to our centre for assessment of their suitability for heart transplantation (HTX) between May 1991 and December 1996 and who performed a graded symptom-limited bicycle exercise test with measurement of respiratory gas analysis, including VO 2 peak.…”

“…Our aim was therefore to analyse whether PP adds prognostic precision to VO 2 peak in patients with advanced CHF, who were referred to our centre for assessment of their suitability for heart transplantation (HTX) between May 1991 and December 1996 and who performed a graded symptom-limited bicycle exercise test with measurement of respiratory gas analysis, including VO 2 peak. 9 Blood pressure (BP) was measured by the auscultatory technique using the STBP-78 device (Colin, Komaki, Japan) or directly by trained investigators, at rest in the sitting position before the exercise test. PP was calculated as the difference between systolic and diastolic BP, and mean BP as diastolic BP plus one-third of PP.…”

“…We used an existing database 9 to assess the prognostic significance of a low PP in patients with advanced CHF, mainly to determine whether PP adds prognostic precision to the generally accepted prognostic value of VO 2 peak. 8,9 Drug treatment for CHF was based on ACE inhibitors, diuretics and digoxin, which is compatible with common practice at the time of the study.…”