Abstract
The 6 minute walk test (6 MWT) has been shown to provide a clinically useful index of functional capacity in chronic heart failure. We hypothesized that similar results would be found in patients who had a recent (ie, within a week) myocardial infarction (MI). Twenty-five patients (23 males, aged 43 to 72 years) who had undertaken an exercise stress test without complications underwent 3 consecutive 6 MWTs (1 hour apart). Heart rate, systolic and diastolic blood pressure, the level of perceived exertion (Borg scale), and the walking distance were determined. In addition, chest pain was assessed by a 0 to 10 numerical rating scale (NRS) and the ECG was continuously monitored. All subjects were able to successfully complete the exercise tests without major cardiovascular complications: mild chest pain (NRS 1 to 3) was found in 3 patients. A Bland-Altman analysis revealed that the mean bias ± 95% confidence interval of the differences on distance walked between test 2 - test 1 were substantially higher than test 3 - test 2 differences (18 ± 66 m and 6 ± 41 m, respectively). The intraclass correlation coefficients were consistently high for all physiological and sensorial responses at the end of the 6 MWTs (range, 0.75 to 0.95). The 6 MWT is a safe and reproducible measurement of functional capacity in stable patients after a noncomplicated MI, even when performed within a week of the event. Therefore, this test might be useful for the evaluation of exercise tolerance in phases I and II of inpatient cardiovascular rehabilitation programs or to assess functional responses to selected interventions.
