Energizing Diastole

Myocardial oxygen consumption change predicts left ventricular relaxation improvement in obese humans after weight loss

Obesity adversely affects myocardial metabolism, efficiency, and diastolic function. Our objective was to determine whether weight loss can ameliorate obesity-related myocardial metabolism and efficiency derangements and that these improvements directly relate to improved diastolic function in humans. We studied 30 obese (BMI >30 kg/m2) subjects with positron emission tomography (PET) (myocardial metabolism, blood flow) and echocardiography (structure, function) before and after marked weight loss from gastric bypass surgery (N = 10) or moderate weight loss from diet (N = 20). Baseline BMI, insulin resistance, hemodynamics, left ventricular (LV) mass, systolic function, myocardial oxygen consumption (MVO2), and fatty acid (FA) metabolism were similar between the groups. MVO2/g decreased after diet-induced weight loss (P = 0.009). Total MVO2 decreased after dietary (P = 0.02) and surgical weight loss (P = 0.0006) and was related to decreased BMI (P = 0.006). Total myocardial FA utilization decreased (P = 0.03), and FA oxidation trended lower (P = 0.06) only after surgery. FA esterification and LV efficiency were unchanged. After surgical weight loss, LV mass decreased by 23% (Doppler-derived) E/E' by 33%, and relaxation increased (improved) by 28%. Improved LV relaxation related significantly to decreased BMI, insulin resistance, total MVO2, and LV mass but not FA utilization. Decreased total MVO(2) predicted LV relaxation improvement independent of BMI change (P = 0.02). Weight loss can ameliorate the obesity-related derangements in myocardial metabolism and LV structure and diastolic function. Decreased total MVO2 independently predicted improved LV relaxation, suggesting that myocardial oxygen metabolism may be mechanistically important in determining cardiac relaxation.

D-ribose, a metabolic substrate for congestive heart failure

The incidence of congestive heart failure continues to escalate worldwide, taxing health care systems. Current therapies focus on clinical management. Current accepted regimens have provided some success; however, most patients show progression of their disease. Because of this failure, research continues to explore therapies directed at stabilization of their disease and hopefully to improve the downward spiral. Publications have asserted that the failing heart is energy starved. D-ribose, a naturally occurring pentose carbohydrate and a key component in the adenosine triphosphate (ATP) molecule, has demonstrated an ability to replenish ATP levels and improve diastolic dysfunction following myocardial ischemia, which has been shown to improve the clinical state of patients afflicted with congestive heart failure. D-ribose may provide the necessary metabolic substrate to benefit this energy-deficient state found in heart failure.