Prognostic value of the six-minute walk test in patients after myocardial infarction

Abstract

Introduction: Evaluation of prognosis after myocardial infarction (MI) represents an essential issue for establishing the strategy of further management. Post-infarct impairment of exercise capacity is a negative prognosticator associated with an increased incidence of death and cardiovascular events. The results of previous studies indicate that the six-minute walk test (6MWT) may be regarded as a safe method of the assessment of functional capacity in patients early after MI, corresponding in terms of workload to the submaximal treadmill exercise test. Aim of the study: The predictive value of the 6MWT in relation to exercise capacity 6 months after MI was investigated. Material and methods: This prospective study included 106 patients, 26 women and 80 men, aged 58±8 years with acute MI. All the subjects underwent echocardiographic examination and the 6MWT, which were performed twice: on the 7th day and 6 months after MI. The enrollees were subjected to an early in-hospital cardiac rehabilitation and were advised to take part in further out-hospital rehabilitation programs. Results: Participating/participation in out-hospital cardiac rehabilitation was associated with a significant improvement in the distance of the 6MWT 6 months after MI only in the group with a reduced distance of the 6MWT at baseline (437±71 vs. 538±103 m; p < 0.001). Apart from rehabilitation, other independent determinants of improvement in the distance of the 6MWT at follow-up were: younger patient's age, male sex, lower peri-infarct glycaemia and, additionally - in the group with lower exercise capacity at baseline-improvement in left ventricular ejection fraction. The distance of the 6MWT carried out on the 7th day after MI < 545 m was characterized by 74% sensitivity, 74% specificity, 74% accuracy, 84% positive predictive value and 61% negative predictive value in the prediction of improvement in exercise capacity at 6 months expressed as =10% increase in the distance of the 6MWT. Conclusions: The 6MWT performed early after MI may be helpful in predicting a subsequent improvement in exercise capacity. The 6MWT can be used as a valuable diagnostic tool in the selection of patients who would most benefit from out-hospital cardiac rehabilitation. Copyright © 2013 Cornetis.