Heart failure (HF) with preserved ejection fraction (HFpEF) is a distinct phenotype hallmarked by clinical signs and symptoms of HF coupled with a normal ejection faction (EF ≥ 50%) and evidence of increased left ventricular (LV) pressures and impaired LV filling on echocardiography. HFpEF is highly prevalent, accounting for up to 50% of all patients with HF, and is associated with significant morbidity and mortality. HFpEF is a heterogenous disorder, contributed to by comorbidities that include hypertension, diabetes, obesity, coronary artery disease (CAD), chronic kidney disease (CKD), and specific causes such as cardiac amyloidosis. These chronic conditions complicate the management of HF and have a significant impact on its prognosis. How to generate specific recommendations addressing many of these conditions in the setting of HF is challenging given the current state of the evidence.

Obesity is a growing global concern, and is a common finding in the progression of HFpEF. According to the World Health Organization (WHO), percentage of adult population that is obese in Egypt is 32% which makes it ranks 18th with the highest prevalence of obesity worldwide. Very few studies have been published about the burden of diseases in Egypt in general, and the burden of obesity is even more complex as the impact of obesity is a result of its comorbidities rather than a direct effect. Several studies have provided evidence for the distinct obesity related HFpEF phenotype, and its unique pathophysiology based on the obesity criteria for the European and American population with a body mass index (BMI) greater than 30 kg/m2. Obesity is a commonly occurring comorbidity in patients with HFpEF, and has many deleterious effects on the cardiovascular system, mediated by changes in volume overload, cardiac load, energy substrate utilization, tissue metabolism, and systemic inflammation. However, based on latest heart failure guidelines, evidence gaps and future research directions are needed to assess efficacy and safety of weight loss management and treatment strategies in patients with HF and obesity.

Metformin is a common anti-diabetic drug with both systemic and cardioprotective benefits in addition to its hypoglycaemic effect. At the cellular level metformin activates adenosine monophosphate-activated protein kinase (AMPK) an important regulator of several metabolic pathways resulting in enhanced glucose utilisation, reduction of protein synthesis and improvement of mitochondrial function. Furthermore, metformin has been shown to reduce collagen accumulation and potentially reduce LV hypertrophy and improve diastolic function in the diabetic myocardium. The cardio protection afforded by metformin treatment seems to result from interference with TGF-beta signaling pathway and activation of the AMP-kinase signaling cascade. A recent systematic review and meta regression analysis have shown that metformin treatment was associated with a reduction in mortality in patients with HFpEF. In addition, treatment with metformin of non-diabetic metabolic syndrome patients with diastolic dysfunction, on top of lifestyle counseling, was associated with improved diastolic function. Moreover, some studies have shown that metformin can reduce body weight. However, metformin has not been officially approved as a medicine for weight loss because its effect on different populations remains inconsistent. No studies to date assessed the role of metformin in obese non-diabetic patients with HFpEF Accordingly, investigators aimed to evaluate if metformin can improve diastolic function in non-diabetic obese patients with HFpEF. Investigators also aimed to assess the impact of this therapy in functional capacity, weight loss and health-related quality of life (HRQoL).