Reversal of Obese/Diabetic Cardiomyopathy After Gastric Bypass Surgery
Condition: Cardiomyopathy
MeSH terms: Cardiomyopathies; Diabetic Cardiomyopathies
Study type: Observational

Summary: 
      The overall purpose of this study is to evaluate the effect of gastric bypass surgery-induced
      weight loss on the heart's function and on fat deposits in the heart muscle.
    

Detailed description: 
      Diabetes is a major risk factor for heart failure. Moreover, patients with diabetes and heart
      failure have a worse survival than those without diabetes. We know that patients with
      diabetes have altered heart metabolism, structure, and function. It is unclear if these
      alterations can be ameliorated with weight loss. We would like to learn whether cardiac
      metabolism, structure, and function in diabetic patients with heart failure symptoms can be
      improved with marked weight loss after gastric bypass surgery.

      Study Day 1. Screening. We will screen subjects with known diabetes or those with a high
      likelihood of diabetes who will undergo gastric bypass surgery. We will approach all patients
      at the Bariatric Surgery clinic regarding enrollment in our study. If they agree to
      participate, they will answer simple questionnaires re: medical history, obesity information,
      and MRI/MRS exclusion (see Appendices). We will obtain their permission to review their
      medical charts.

      Study Day 2. Screening will include a physical examination and phlebotomy for a complete
      blood count, oral glucose tolerance test, & comprehensive metabolic profile and a screening
      rest and stress echocardiogram. The rest and stress echocardiogram will be used to exclude
      cardiac abnormalities other than diastolic dysfunction. Optison™ or Definity will be used as
      needed for the echocardiograms. We will determine the subjects' fat and fat-free mass using
      dual-energy X-ray absorptiometry (DXA) imaging at the Center for Applied Research Sciences
      unit.

      Study Day 3. Baseline Imaging Studies. Subject preparation. We expect 30 subjects to complete
      our study's screening tests and meet our study criteria. The evening before imaging Study
      Days 3 & 4, subjects will be admitted to The Center for Applied Research Sciences Intensive
      Research Unit in order to standardize their metabolic milieu for their myocardial fat imaging
      studies. At 1800, subjects will ingest a standard meal containing a total of ~700 kcal for
      the subjects. Carbohydrate, fat, and protein will represent 55, 30, and 15%, respectively, of
      total energy intake. At 2000, subjects will ingest a defined liquid formula snack containing
      250 kcal, 40 g carbohydrate, 6.1 g fat, and 8.8 g protein (Ensure, Ross Laboratories,
      Columbus, OH). After this snack, all subjects will fast until completion of the study the
      following day. Subjects will be given a lunch after completing their imaging studies.
      Magnetic resonance imaging (MRI). Subjects will be placed in the gantry of the scanner.
      Examinations will be performed on the 1.5T scanner using ECG gating, breath-hold, and a chest
      array coil This same scanner will be used for 1H-Magnetic resonance spectroscopy (MRS). The
      MRS protocol is based on a free-breathing, point-resolved spectroscopy (PRESS) sequence with
      both ECG and two-dimensional respiratory gating optimized for accuracy and robustness.
      Subject care. All subjects will be given a lunch, prepared at the Intensive Research Unit
      after imaging is completed. All imaging should be completed by 12PM. If the physician
      monitoring the subject determines that the subject would benefit from furosemide 20mg, p.o. x
      1, or KCl, p.o. - a 10 day course may be provided (with a follow-up K+ check). Patients'
      physicians would be notified of any changes. We request subjects stay on their same medical
      regimen throughout the testing period. We recognize that this may not be possible for all
      subjects.

      Gastric bypass. Subjects will undergo surgery after Study Day 3. The same surgeon (J.C.E.)
      will perform all bypass procedures using standard techniques. Briefly, a small (~20 mL)
      proximal gastric pouch will be created by stapling across the stomach, and a 150 cm Roux-Y
      limb constructed by transecting the jejunum 30cm distal to the ligament of Treitz and
      creating a jejunojejunostomy 150 cm distal to the transection.

      Study Day 4. Imaging Studies - 3 months after surgery. Subjects will undergo the same imaging
      studies under the same conditions and in the same order as on Study Day 3 except that
      subjects on Day 4 will also undergo a resting echocardiogram for diastolic function.
    

Observational model: Case-Only
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Obese patients +/- known diabetes who will undergo gastric bypass surgery.
      
Biospecimen description: 
      Blood samples
    
Keywords: Reversal of Obesity-related and Diabetic Cardiomyopathy