title: Paradoxical increase in ventricular torsion and systolic torsion rate in type I diabetic patients under tight glycemic control.
abstract: OBJECTIVE
  This study sought to characterize the early features of diabetic cardiomyopathy by magnetic resonance imaging (MRI) tagging.
  
  
  BACKGROUND
  The earliest manifestations of diabetic cardiomyopathy have not been well established, especially under tight glycemic management. We hypothesized that torsion measurements would identify subclinical contractile alterations in type I diabetics with normal left ventricular ejection fraction, mass, blood pressure, and aggressive glycemic control. We also sought to characterize the influence of elevated resting heart rates (HRs) of diabetics on torsion.
  
  
  METHODS
  Sixteen patients with type I diabetes and 10 control patients underwent cine and tagged MRI with a 1.5-T scanner. Torsion, strain, and their rates were measured. To quantify the influence of chronotropic and inotropic stimulation on torsion, nine healthy volunteers underwent MRI tagging at rest, after atropine injection, and after exercise.
  
  
  RESULTS
  Diabetic patients (hemoglobin A1c, 6.8 +/- 0.4%) had a higher resting HR (77.0 +/- 12.4 beats/min vs. 59.0 +/- 5.6 beats/min; p < 0.01), higher maximal torsion by 23% (3.5 +/- 0.9 degrees/cm vs. 2.7 +/- 0.4 degrees/cm; p < 0.01) and higher maximal systolic torsion rate (TR-s) by 25% (0.013 +/- 0.003 degrees/cm/s vs. 0.010 +/- 0.002 degrees/cm/s, p = 0.01). Torsion did not significantly change with chronotropic stimulation (p = 0.30).
  
  
  CONCLUSIONS
  In diabetics under tight glycemic control, we observed a surprising increase in torsion and TR-s unrelated to chronotropic influences of HR. We propose that increased torsion and TR-s could represent early predictive markers of the propensity to cardiac dysfunction in asymptomatic type I diabetics. Furthermore, these findings seem fundamental to the diabetic state itself and unaccounted for by other comorbidities.
authors.affiliation: Cardiovascular Magnetic Resonance Laboratories, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Jina
authors.initials: J
authors.lastname: Chung
authors.forename: Paul
authors.initials: P
authors.lastname: Abraszewski
authors.forename: Xin
authors.initials: X
authors.lastname: Yu
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Krainik
authors.forename: Marvin
authors.initials: M
authors.lastname: Ashford
authors.forename: Shelton D
authors.initials: SD
authors.lastname: Caruthers
authors.forename: Janet B
authors.initials: JB
authors.lastname: McGill
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Wickline
mesh_terms: D000328:Adult; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy / Q000503:physiopathology*; D003925:Diabetic Angiopathies / Q000175:diagnosis* / Q000503:physiopathology; D005080:Exercise Test; D005260:Female; D020342:Finite Element Analysis; D006339:Heart Rate; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000627:therapeutic use; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D014102:Torsion Abnormality; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology*
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin