Abstract
BackgroundThis study compared changes in measured versus predicted peak aerobic power (V̇O2peak) following cardiovascular rehabilitation (CR). Peak cardiopulmonary exercise testing (CPET) results were compared to four V̇O2peak estimation methods: the submaximal modified Bruce treadmill, Astrand-Ryhming cycle ergometer, and Chester step tests, and the Duke Activity Status Index (DASI).MethodsAdults with cardiovascular disease (CVD) who completed a 12-week CR program were assessed at baseline and 12 weeks follow-up. CPET, the DASI and three subsequent submaximal exercise tests were performed in a random order.ResultsOf the 50 adults (age: 57 ± 11 years) who participated, 46 completed the 12-week CR program and exercise tests. At baseline 69, 68, and 38% of the treadmill, step and cycle tests were successfully completed, respectively. At follow-up 67, 80, and 46% of the treadmill, step and cycle tests were successfully completed, respectively. No severe adverse events occurred. Significant improvements in V̇O2peak were observed with CPET (3.6 ± 5.5 mL.kg–1.min–1, p < 0.001) and the DASI (2.3 ± 4.2 mL.kg–1.min–1, p < 0.001). Bland-Altman plots of the change in V̇O2peak between CPET and the four V̇O2peak estimation methods revealed the following: a proportional bias and heteroscedastic 95% limits of agreement (95% LoA) for the treadmill test, and for the cycle and step tests and DASI, mean bias’ and 95% LoA of 1.0 mL.kg–1.min–1 (21.3, −19.3), 1.4 mL.kg–1.min–1 (15.0, −12.3) and 1.0 mL.kg–1.min–1 (13.8, −11.8), respectively.ConclusionGiven the greater number of successful tests, no serious adverse events and acceptable mean bias, the step test appears to be a valid and safe method for assessing group-level mean changes in V̇O2peak among patients in CR. The DASI also appears to be a valid and practical questionnaire. Wide limits of agreement, however, limit their use to predict individual-level changes.
Highlights
Cardiovascular rehabilitation (CR) programs have been consistently shown to improve patients’ peak aerobic power (V O2peak), which independently predicts lower all-cause and cardiovascular disease-specific mortality (Keteyian et al, 2008; Kodama et al, 2009)
The assessment of V O2peak, as measured by symptomlimited cardiopulmonary exercise testing with ergospirometry (CPET), remains the “gold-standard” for assessing patients’ cardiopulmonary responses to CR (Canadian Association of Cardiac Rehabilitation, 2009); it is used for risk stratification and the development of safe and effective exercise programs (Canadian Association of Cardiac Rehabilitation, 2009)
Fifty participants met the eligibility criteria and consented to participate; the remaining 24 candidates declined for the following reasons: lack of time (n = 6); illness or worsening of symptoms (n = 5); did not want to delay starting CR to complete baseline study measures (n = 4); lack of interest (n = 4); fearful of CPET (n = 2); no longer enrolled in CR (n = 1); not available for study appointments (n = 1); or, had pacemaker which limited exercise heart rate (HR) (n = 1)
Summary
Cardiovascular rehabilitation (CR) programs have been consistently shown to improve patients’ peak aerobic power (V O2peak), which independently predicts lower all-cause and cardiovascular disease-specific mortality (Keteyian et al, 2008; Kodama et al, 2009). A number of submaximal exercise tests [terminated at intensities at or below 85% of peak heart rate (HR)] and questionnaires have been developed to reduce testing costs, time, resources, and risks (Hlatky et al, 1989; Noonan and Dean, 2000; Arena et al, 2007). This study compared changes in measured versus predicted peak aerobic power (V O2peak) following cardiovascular rehabilitation (CR). Peak cardiopulmonary exercise testing (CPET) results were compared to four V O2peak estimation methods: the submaximal modified Bruce treadmill, Astrand-Ryhming cycle ergometer, and Chester step tests, and the Duke Activity Status Index (DASI)
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