Functional evaluation of ultra-octogenarian patients undergoing Cardiac Rehabilitation: correlation between Six minute Walking Test and Rivermead Mobility Index

Background. There is an increasing need for admission of octogenarians to cardiac rehabilitation programs. The aim of this study was to evaluate if the Rivermead Mobility Index (RMI) (scale of mobility) is related to the functional capacity assessed by the 6 Minute Walking Test (6MWT). Methods. We selected 108 consecutive patients ≥ 80 years (M = 53, mean age 82.5 ± 2.7 years, after cardiac surgery n = 72, heart failure n = 36) enrolled to our cardiac rehabilitation unit. All patients were evaluated with the RMI and underwent 6MWT both at admission (RMI1 and 6MWT1) and after a period of daily physical training (RMI2 and 6MWT2). The RMI2/RMI1 and 6MWT2/6MWT1 ratios were calculated as indexes of functional improvement (IM). Results. The average in hospital stay was 20 ± 11 days with an average of 11.9 training sessions per patient. The average distance walked at 6MWT1 and 6MWT2 was 193 ± 116 and 278 ± 122 m, respectively (p <0.001). The average score of RMI1 and RMI2 was 8.5 ± 3.4 and 13.1 ± 2.9, respectively (p <0.001). The values of 6MWT1 and RMI1 results were significantly correlated (r = 0.56, p <0.001). The RMI IM was significantly correlated to 6MWT IM (r = 0.309, p = 0.002). At multivariate analysis, RMI IM was found to be predictive of 6MWT IM even after correction for age, gender, length of hospitalization and number of sessions of training. Conclusions. In octogenarians, cardiac rehabilitation results in a significant improvement of both RMI and 6MWT. RMI IM is independently correlated to 6MWT IM. Therefore, RMI could be a useful tool for evaluating the improvement of functional capacity even in patients who cannot undergo 6MWT.