Relationship Between Left Ventricular Structural and Metabolic Remodeling in Type 2 Diabetes

Abstract

Concentric left ventricular (LV) remodeling is associated with adverse cardiovascular events and is frequently observed in patients with type 2 diabetes mellitus (T2DM). Despite this, the cause of concentric remodeling in diabetes per se is unclear, but it may be related to cardiac steatosis and impaired myocardial energetics. Thus, we investigated the relationship between myocardial metabolic changes and LV remodeling in T2DM. Forty-six nonhypertensive patients with T2DM and 20 matched control subjects underwent cardiovascular magnetic resonance to assess LV remodeling (LV mass-to-LV end diastolic volume ratio), function, tissue characterization before and after contrast using T1 mapping, and (1)H and (31)P magnetic resonance spectroscopy for myocardial triglyceride content (MTG) and phosphocreatine-to-ATP ratio, respectively. When compared with BMI- and blood pressure-matched control subjects, subjects with diabetes were associated with concentric LV remodeling, higher MTG, impaired myocardial energetics, and impaired systolic strain indicating a subtle contractile dysfunction. Importantly, cardiac steatosis independently predicted concentric remodeling and systolic strain. Extracellular volume fraction was unchanged, indicating the absence of fibrosis. In conclusion, cardiac steatosis may contribute to concentric remodeling and contractile dysfunction of the LV in diabetes. Because cardiac steatosis is modifiable, strategies aimed at reducing MTG may be beneficial in reversing concentric remodeling and improving contractile function in the hearts of patients with diabetes.

Figure 1

Differences in cardiac geometry and function between patients with T2DM and controls; (A) LV Mass: LV-EDV ratio (g/ml), (B) Systolic strain %, (C) Myocardial triglyceride content (%) and (D) Myocardial energetics (PCr/ATP ratio).

Figure 2

Representative examples of cardiac ³¹P-MRS, ¹H-MRS and cine imaging in a control and a patient with T2DM. Top panel: normal control ³¹P-MRS with PCr/ATP=2.16, vs patient with T2DM PCr/ATP= 1.54; Second panel: normal control 1H-MRS with myocardial lipid to water ratio=0.44%, vs patient with T2DM= 1.74%; Third panel: normal control cine image with LV mass : LV end-diastolic volume ratio=0.55 g/ml, vs patient with T2DM = 1.28g/ml.