Investigating Insulin Resistance in Pediatric Cardiomyopathy - A Pilot Study

Abstract

Children with cardiomyopathy are a vulnerable population and understanding the factors that contribute to cardiac dysfunction are of great importance. At the biochemical level, energy utilization by cardiomyocytes during stress may provide insight into the progression of cardiomyopathy. There is a large body of literature that describes insulin resistance in adults with cardiomyopathy (1,2). Extensive literature on the topic in adult individuals exists however investigation in the pediatric population is sparse. The pathophysiology of disease in children and adolescents is unique. To study the role of insulin resistance in pediatric cardiomyopathy, we measured the homeostasis model assessment-estimated insulin resistance (HOMA-IR) at baseline in pre-pubertal patients (age 13-18 years old; mean 16 years old; n = 8) with either hypertrophic cardiomyopathy (HCM) or dilated cardiomyopathy (DCM). In patients with HCM, greater insulin resistance was positively correlated with greater left ventricular (LV) septal thickness (r = 0.55; p = 0.33; n = 5) and LV posterior wall thickness (r = 0.7; p = 0.19; n = 5) during diastole. As expected, insulin resistance was strongly correlated with BMI (r = 0.84; p = 0.08; n = 5) though greater BMI was not as strongly associated with LV septal thickness (r = 0.59; p = 0.3; n = 5) or posterior wall thickness (r = 0.59; p = 0.3; n = 5). In patients with DCM, insulin resistance was positively correlated with LV end diastolic volume (r = 0.59; p = 0.59; n = 3). Interestingly, there was an observed inverse association between insulin resistance and BMI in DCM (r = -0.85; p = 0.34; n =3). Though our sample population is limited, thus affecting statistical significance, results showed that there was a trend towards greater insulin resistance in patients with poorer cardiac measurements. These findings are consistent with adult literature and the proposition that cardiac dysfunction is an insulin resistant state.