Methods of Evaluation of Tolerance yo Physical Activity Based on Six-Minute Walking Test During Outpatient Rehabilitation of Patients with Ischemic Heart Disease

Background. Even though the six-minute walking test is a simple and widely available tool for the evaluation of the functional capacity of cardiac patients, its interpretation is associated with some difficulties and contradictions. Aims: To evaluate the dynamics of tolerance to physical activity during outpatient rehabilitation of patients with ischemic heart disease using predicted values of distance in the six-minute walking test. Materials and methods. 97 patients (70 men and 27 women, average age 59.6 [50; 60] years) after acute coronary syndrome and after myocardial revascularization were included. The six-minute walking test was performed at the beginning of the 3-weeks stage of cardiac rehabilitation and before the patients’ discharge. The results of the test were reported as an absolute value, a change in absolute value, and the percentage of predicted values, estimated with the reference equation by Enright and colleagues. Results. The absolute value of distance in the six-minute walking test was increased significantly from 418 [385; 465] m to 485 [440; 525] m (p <0.001). The number of patients with a distance less than 300 m was decreased significantly (12 patients, 12% vs 2 patients, 2%, p <0.001). In most patients, the absolute increase in distance was 30 m and more (81 people, 84%). After comparing the perceived data with the calculated predicted values, it was revealed that the distance raised from 79 [71; 82]% to 92 [88; 96]% of the predicted values. And 56 patients (58%) had a distance equal to 90% or more from its predicted value. Conclusions. During the third stage of cardiac rehabilitation the significant increase of the absolute value of the six-minute walking test, the growth of the percentage of predicted values, and the decrease of patients with a distance less than 300 m were found. All these estimation methods may be used to demonstrate and prove favourable changes of tolerance to physical activity in patients with ischemic heart disease.