Association Between Gait Speed as a Measure of Frailty and Risk of Cardiovascular Events After Myocardial Infarction

Objectives This study sought to determine the additional clinical value of gait speed to Framingham risk score (FRS), cardiac function, and comorbid conditions in predicting cardiovascular events in patients with ST-segment elevation myocardial infarction. Background There is growing evidence that gait speed is inversely associated with all-cause mortality, particularly cardiovascular mortality, among the elderly. Methods We undertook a single-center prospective observational study of gait speed in 472 patients with ST-segment elevation myocardial infarction in Japan, between 2001 and 2008. Gait speeds were measured using a 200-m course before discharge in all patients, and we followed up cardiovascular events, which consist of cardiovascular deaths, nonfatal myocardial infarctions, and nonfatal ischemic strokes. Results During the 2,596 person-years of follow-up, 83 patients (17.6%) experienced cardiovascular events. Cardiovascular events increased across decreasing tertiles of gait speed (fastest tertile: n = 5, 3.2%; middle tertile: n = 20, 12.6%; slowest tertile, n = 58, 36.7%). By multiple adjusted Cox proportional hazards analysis, gait speed was a significant and independent predictor of cardiovascular events (hazard ratio for increasing 0.1 m/s of gait speed: 0.71, 95% confidence interval [CI]: 0.63 to 0.81, p < 0.001). The addition of gait speed to the model incorporating FRS, B-type natriuretic peptide levels, and comorbidity index improved reclassification (net reclassification index: 32.8%, 95% CI: 17.4 to 48.3, p < 0.001) and the C-statistics with a reasonable global fit and calibration (C-statistics: from 0.703 [95% CI: 0.636 to 0.763] to 0.786 [95% CI: 0.738 to 0.829]). Conclusions Among patients with ST-segment elevation myocardial infarction, slow gait speed was significantly associated with an increased risk of cardiovascular events. (Gait Speed for Predicting Cardiovascular Events After Myocardial Infarction; NCT01484158) (C) 2013 by the American College of Cardiology Foundation