Exercise Capacity and Left Ventricular Mass in Individuals with Type 2 Diabetes Mellitus

Abstract

Left ventricular hypertrophy (LVH) and type 2 diabetes mellitus (DM) are considered independent risk factors for mortality. Exercise capacity is inversely and independently associated with lower mortality risk in diabetics and with lower LV mass in some populations. The association between exercise capacity and LV mass in diabetic patients has not been studied. PURPOSE: To assess the association between LV mass and exercise capacity in individuals with type 2 DM. METHODS: From 1986 to 2009, 647 individuals with type 2 DM (mean age: 65±11), underwent an exercise stress test and echocardiographic evaluation at the Veterans Affairs Medical Center, Washington, DC. We established three fitness categories based on the age and MET level achieved. Individuals with a peak MET level within the 20th percentile of their respective age group (mean: 4.3±0.8 MET) comprised the Low-Fit category (n=134). Those who achieved a MET level between the 21st and 85th percentile (mean: 6.5±1.1 MET) comprised the Moderate-Fit category (n=381) and those with a peak MET level above the 85th percentile (mean: 8.8±1.0 MET), comprised the High-Fit category (n=132). Left ventricular mass (LVM) was calculated by a standardized formula (Penn) and was then indexed to body size by dividing LVM by height in meters to the allometric power of 2.7 to obtain LVM index. LVH was defined as LVM index >50 g/m2.7. RESULTS: Exercise capacity was inversely associated with LVM Index and the risk for LVH. For every 1-MET increase in exercise capacity the risk for having LVH was lowered by 17% (Hazard Ratio=0.83; CI: 0.78-0.91; p<0.001). Echocardiographic parameters were significantly different (p<0.02) among all groups (Table). Systolic BP at 3 minutes of exercise was significantly lower in the High-Fit group compared to Low-Fit group. We noted a 12% increase in the risk for LVH for every 10 mm Hg increase in systolic BP at 3 minutes of exercise.TABLECONCLUSIONS: Exercise capacity is a strong predictor of LV mass in individuals with type 2 DM. The association is inverse and graded.