Metabolic syndrome is associated with delayed heart rate recovery after exercise

Heart rate (HR) recovery after exercise is a function of vagal reactivation, and its impairment is a predictor of overall mortality and adverse cardiovascular events. While metabolic syndrome is associated with sympathetic overactivity, little is known about the relationship between metabolic syndrome and HR recovery. A symptom-limited exercise stress test in healthy subjects (n=1, 434) was used to evaluate HR recovery. Metabolic syndrome was defined according to the National Cholesterol Education Program's Adult Treatment Panel III (NCEP ATP-III) criteria. Seventeen percent of subjects had > or =3 criteria for metabolic syndrome. HR recovery was lower in men than women and in smokers than nonsmokers. The subject with metabolic syndrome (vs. without) showed lower HR recovery (10.3+/-11.6 vs. 13.6+/-9.7 per minute) and higher resting HR (64.3+/-10.3 vs. 61.6+/-9.1 per minute). HR recovery correlated inversely to age (r=-0.25, p<0.0001), but not to resting HR or maximal oxygen uptake. Delayed HR recovery was associated with metabolic syndrome after an adjustment for age, sex, resting HR and smoking (p<0.01). Metabolic syn-drome is associated with impaired vagal reactivation. Adverse cardiovascular out-comes associated with metabolic syndrome may be mediated by the failure of vagal reactivation in addition to sympathetic overactivity.