Comparison of the Korean Activity Status Index with cardiopulmonary exercise test in patients with acute myocardial infarction

Abstract

This study aimed to compare the Korean Activity Status Index (KASI) with the cardiopulmonary exercise test (CPET) among patients with acute myocardial infarction. A total of 2,268 patients (85.4% male; mean age, 59.3±10.2 years; range, 23-90 years) diagnosed with acute myocardial infarction were enrolled in the Regional Center Myocardial Infarction Registry between July 2016 and June 2019. The KASI is a tool used to measure functional capacity by asking patients about their ability to perform specific activities and then scoring their responses. In contrast, CPET is the gold standard for assessing the objective functional capacity in patients undergoing cardiac rehabilitation. Peak oxygen uptake (VO_2peak) was used to analyze the correlation. Patients who completed two consecutive KASI and CPET evaluations during their first (KASI_1, VO_2peak_1) and second visits (KASI_2, VO_2peak_2) for cardiac rehabilitation were included in the study. The mean KASI_1 and KASI_2 scores were 43.3±14.3 and 49.8±13.9, respectively, and the mean VO_2peak_1 and VO_2peak_2 scores were 25.9±8.0 and 28.5±8.3, respectively. Both the KASI scores were significantly correlated with the measured VO_2peak during each visit, with correlation coefficients of 0.385 (<i>P</i><0.001) and 0.346 (<i>P</i><0.001), respectively. Moreover, the KASI score and VO_2peak had a linear relationship (VO_2peak_1=0.22×KASI_1+16.5, <i>P</i><0.001; VO_2peak_2=0.21×KASI_2+18.2, <i>P</i><0.001). This study revealed that the KASI is a valid measure for the follow-up evaluation of the functional capacity of patients. These findings suggest that VO_2peak can be predicted using the KASI score in patients who do not undergo CPET.