['To characterize the extent to which metabolic syndrome criteria predict left ventricular (LV) structure and function.', "Metabolic syndrome criteria were assessed in 607 adults with normal LV function. The cohort was grouped according to the number of criteria satisfied: (1) Absent (0 criteria, n = 110); (2) Pre-Metabolic Syndrome (1-2 criteria, n = 311); and (3) Metabolic Syndrome (>or=3 criteria, n = 186). Echocardiography was used to assess LV structure (LV mass) and systolic (LVEF, Vs) and diastolic function, by pulse-wave Doppler (E/A ratio) and tissue Doppler imaging (Ve). LV volumes and LVEF were similar between groups. However, LV mass increased significantly and progressively (LVM/Ht(2.7), in g/m(2.7): 34.9 +/- 6.7, 41.0 +/- 9.5, 46.3 +/- 11.0, P < 0.001); LV relaxation decreased progressively (Ve(global'), in cm/s: 13.5 +/- 2.8, 12.1 +/- 3.0, 10.5 +/- 2.2, P < 0.001) from Absent to Pre-Metabolic Syndrome to Metabolic Syndrome groups, respectively. Multiple variable analyses showed that diastolic blood pressure, waist circumference, and triglyceride levels were independent predictors of Ve after adjustment for LV mass."] Is metabolic syndrome associated with abnormal left ventricular diastolic function independent of left ventricular mass?