Abstract 17699: Left Ventricular Metabolism, Function and Sympathetic Innervation in Type 1 Diabetes
Objective: In type 1 diabetes (T1DM), alterations in left ventricular (LV) function may occur in the absence of coronary artery disease, possibly due to alterations in sympathetic innervation and myocardial oxidative metabolism and efficiency (Eff). We evaluated the association between glucose control, LV myocardial metabolism and Eff, and LV function and innervation in patients with T1DM with no evidence of chronic complications.
Methods: Cross-sectional study in 35 subjects with T1DM, 50% females, mean age 35±13 years, DM duration 13±6 years, mean HbA1c 8.0±1.2%. Global and regional LV oxidative metabolism was derived using positron emission tomography (PET) to obtain kmono, the clearance rate of 11C acetate. LV Eff was calculated as: (stroke volume index: SVI, systolic blood pressure: SBP, heart rate: HR). Sympathetic innervation was assessed using 11C meta-hydroxyephedrine (HED) PET and analyzed as the HED retention index (RI). Conventional and tagged cardiac magnetic resonance imaging (CMR) was used to assess global and regional LV function, including SVI and peak torsion. Associations between HED RI, LV Eff and LV torsion, and association between glucose control (as measured by HbA1c) and LV function were analyzed by Spearman correlations.
Results: In these subjects mean SVI was 46.7 ml/m2, mean kmono was 0.0625 1/min, and LV Eff ranged from 3.78 x 106 - 1.46 x 107 mmHg*ml/m2. Mean HED RI was 0.0810 mL/min/l and was homogeneous throughout all myocardial segments. Analysis of global and segmental LV Eff and HED RI demonstrated that Eff was inversely related to sympathetic innervation (R=-0.507, p=0.0019). Elevated HbA1c was significantly associated with lower SVI (R = -0.41, P = 0.013). In preliminary analyses, no relationship was found between LV Eff and peak systolic torsion.
Conclusions: In these subjects with T1DM without end-organ damage, higher sympathetic tone was associated with lower myocardial efficiency due to higher rates of oxidative metabolism, and poor glucose control was associated with lower LV function. We found no relationship between LV Eff and regional torsion. Ongoing analyses in a larger cohort are currently evaluating other parameters of LV biomechanics and their relationship to myocardial efficiency and innervation.
- © 2013 by American Heart Association, Inc.