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Effect of Weight Loss on Myocardial Metabolism and Cardiac Relaxation in Obese Adults

This study has been completed.
Sponsor:
Collaborator:
National Heart, Lung, and Blood Institute (NHLBI)
Information provided by (Responsible Party):
Washington University School of Medicine
ClinicalTrials.gov Identifier:
NCT00572624
First received: December 12, 2007
Last updated: May 8, 2017
Last verified: May 2017
  Purpose
Obesity adversely affects myocardial (muscular heart tissue) metabolism, efficiency, and diastolic function. The objective of this study was to determine if weight loss could improve obesity-related myocardial metabolism and efficiency and if these improvements were directly related to improved diastolic function.

Condition Intervention
Obesity Behavioral: Diet Procedure: Gastric bypass surgery

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Effect of Weight Loss on Myocardial Oxygen Consumption and Left Ventricular Relaxation in Obese Adults

Resource links provided by NLM:


Further study details as provided by Washington University School of Medicine:

Primary Outcome Measures:
  • Total Myocardial Oxygen Consumption (MVO2) [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    The evening before an imaging study, all participants were given a meal containing 12 kcal/kg adjusted body weight (=ideal body weight + ((actual body weight-ideal body weight) x 0.25)). Participants fasted until their imaging studies were completed. Myocardial oxygen consumption (MVO2) was measured using positron emission tomography (PET) following injection of 1-^11C-acetate. Total MVO2 was calculated by multiplying the MVO2 measure by left ventricular weight.

  • Total Myocardial Fatty Acid (FA) Utilization [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    The evening before an imaging study, all participants were given a meal containing 12 kcal/kg adjusted body weight (=ideal body weight + ((actual body weight-ideal body weight) x 0.25)). Participants fasted until their imaging studies were completed. Myocardial blood flow was measured using positron emission tomography (PET) following injection of ^30O-water. Myocardial fatty acid (FA) utilization was measured using PET after injection of 1-^11C-palmitate. The calculations that describe the relationship between the different measures of myocardial FA metabolism are: FA utilization/gram = blood flow/gram × FA uptake/gram × [average plasma free FA at the time of the 1-11C-palmitate injection]; FA utilization/gram = FA oxidation/gram + esterification/gram. Total fatty acid utilization was calculated by multiplying the fatty acid utilization rate by left ventricular weight.

  • Total Myocardial Fatty Acid (FA) Oxidation [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    The evening before an imaging study, all participants were given a meal containing 12 kcal/kg adjusted body weight (=ideal body weight + ((actual body weight-ideal body weight) x 0.25)). Participants fasted until their imaging studies were completed. Myocardial fatty acid utilization was measured using positron emission tomography (PET) after injecting 1-^11C-palmitate. Total fatty acid oxidation was calculated by multiplying the fatty acid oxidation rate by left ventricular weight.


Secondary Outcome Measures:
  • Left Ventricular (LV) Relaxation (E') [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    Immediately following MVO2 measurement, complete two-dimensional, M-mode, and Doppler echocardiographic studies were performed using second harmonic imaging. Left ventricular relaxation (E') was measured at the lateral annulus. All reported measurements represent the average of three consecutive cardiac cycles. A single investigator blinded to all clinical parameters evaluated all echocardiograms.

  • Septal Ratio (E/E') [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    Immediately following MVO2 measurement, complete two-dimensional, M-mode, and Doppler echocardiographic studies were performed using second harmonic imaging. The early diastolic (E) velocity was measured, left ventricular relaxation (E') was measured at the lateral mitral annulus, and the E/E'(septal) ratio was calculated. All reported measurements represent the average of three consecutive cardiac cycles. A single investigator blinded to all clinical parameters evaluated all echocardiograms. The normal septal ratio from the lateral mitral annulus is <5, a ratio from 5 to 10 is indeterminate, and a ratio of >10 indicates elevated left atrial pressure.

  • Left Ventricular (LV) Mass [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    Immediately following MVO2 measurement, complete two-dimensional, M-mode, and Doppler echocardiographic study were performed using second harmonic imaging. Left ventricular (LV) mass was measured using the area-length method. All reported measurements represent the average of three consecutive cardiac cycles. A single investigator blinded to all clinical parameters evaluated all echocardiograms.

  • Mean Heart Rate [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    Heart rate was measured at scheduled physical examinations.

  • Mean Arterial Pressure [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    Mean arterial pressure was measured at scheduled physical examinations.

  • Mean Body Mass Index [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    Participant weight and height was measured at scheduled physical examinations. Body mass index was calculated as participant body weight in kilograms divided by their height in meters squared.

  • Mean Total Serum Cholesterol and Triglycerides [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    Blood testing was conducted at scheduled times during the study. Serum cholesterol and triglycerides were measured by the enzymatic method (Roche Diagnostics).

  • Mean Homeostasis Model Assessment of Insulin Resistance [ Time Frame: Measured at baseline, 16 months after gastric bypass surgery-induced weight loss, and 8 months after diet-induced weight loss ]
    The homeostasis model assessment of insulin resistance (HOMA) was used to calculate insulin resistance using the first AM, fasting glucose and insulin levels. Plasma insulin levels were measured by radioimmunoassay, and glucose levels were measured by automated hexokinase assay. A HOMA score of <3 represents normal insulin resistance, a score between 3 and 5 moderate insulin resistance, and a score of 5 or higher represents severe insulin resistance.


Enrollment: 51
Study Start Date: June 2003
Study Completion Date: June 2014
Primary Completion Date: June 2014 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Diet
Participants who received counseling and instruction about weight loss through diet and exercise
Behavioral: Diet
Participants attended 20 group behavioral modification sessions led by a behaviorist, a registered dietician, and a physical therapist. The meal plans ranged from 1200 to 1500 kilocalories per day, depending on subject sex and BMI, and were designed to achieve ≤1% body weight loss/week. Participants completed daily food records, and were taught a variety of weight management skills. The exercise component included strength, flexibility, balance, and endurance instruction, gradually increasing to 30 minutes of exercise 5 days/week.
Experimental: Gastric bypass surgery
Participants who received gastric bypass surgery
Procedure: Gastric bypass surgery
The same surgeon performed all bypass procedures using standard techniques. A small (~20 ml) proximal gastric pouch was created by stapling the stomach, and a 75-cm Roux-en-Y limb was constructed by transecting the jejunum distal to the ligament of Treitz, and creating a jejunojejunostomy 75 cm distal to the transection.

Detailed Description:
This was a prospective, interventional study in obese adults ages 21 to 50 years of age to determine whether weight loss could improve obesity-related myocardial metabolism and efficiency. Two different mechanisms of weight loss were studied: diet and exercise and gastric bypass surgery. Positron emission tomography (PET) was used to quantitate myocardial oxygen consumption (MVO2) and myocardial fatty acid (FA) metabolism. Echocardiography with tissue Doppler imaging was used to quantify cardiac structure, systolic and diastolic function (left ventricular (LV) relaxation (E') and septal ratio (E/E')).
  Eligibility

Ages Eligible for Study:   21 Years to 50 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Body mass index (BMI) > 30 kg/m^2
  • Sedentary lifestyle

Exclusion Criteria:

  • Body weight >159 kg
  • Insulin-requiring diabetes
  • Heart failure
  • History of coronary artery disease
  • Chest pain
  • Untreated sleep apnea
  • Being an active smoker
  • Pregnant, lactating, or postmenopausal
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00572624

Locations
United States, Missouri
Washington University Medical School
Saint Louis, Missouri, United States, 63110
Sponsors and Collaborators
Washington University School of Medicine
National Heart, Lung, and Blood Institute (NHLBI)
Investigators
Principal Investigator: Robert Gropler, MD Washington University Medical School
  More Information

Publications:
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Washington University School of Medicine
ClinicalTrials.gov Identifier: NCT00572624     History of Changes
Other Study ID Numbers: 05-0523 (201105066)
P01HL013851-43 ( U.S. NIH Grant/Contract )
Study First Received: December 12, 2007
Results First Received: December 11, 2014
Last Updated: May 8, 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

Keywords provided by Washington University School of Medicine:
Heart Metabolism
Obesity
Weight loss
Gastric bypass surgery
Diet and exercise

Additional relevant MeSH terms:
Weight Loss
Body Weight Changes
Body Weight
Signs and Symptoms

ClinicalTrials.gov processed this record on September 21, 2017