Effect of Weight Loss on Myocardial Metabolism and Cardiac Relaxation in Obese Adults
- Conditions
- Obesity
- Interventions
- Behavioral: DietProcedure: Gastric bypass surgery
- Registration Number
- NCT00572624
- Lead Sponsor
- Washington University School of Medicine
- Brief Summary
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.
- 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')).
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 51
- Body mass index (BMI) > 30 kg/m^2
- Sedentary lifestyle
- 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
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description Diet Diet Participants who received counseling and instruction about weight loss through diet and exercise Gastric bypass surgery Gastric bypass surgery Participants who received gastric bypass surgery
- Primary Outcome Measures
Name Time Method Total Myocardial Fatty Acid (FA) Oxidation 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.
Total Myocardial Fatty Acid (FA) Utilization 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 Oxygen Consumption (MVO2) 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.
- Secondary Outcome Measures
Name Time Method Mean Body Mass Index 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 Homeostasis Model Assessment of Insulin Resistance 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.
Mean Heart Rate 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 Total Serum Cholesterol and Triglycerides 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 Arterial Pressure 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.
Left Ventricular (LV) Relaxation (E') 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') 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 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.
Trial Locations
- Locations (1)
Washington University Medical School
🇺🇸Saint Louis, Missouri, United States