Heart rate reduction as a marker to optimize carvedilol treatment and enhance myocardial recovery in pediatric dilated cardiomyopathy

Introduction: An elevated heart rate is associated with an increased risk of death or cardiac transplant in children with dilated cardiomyopathy (DCM). Whether heart rate is a clinical marker to address therapy, is poorly investigated in children.Aim: To investigate the relationship between heart rate reduction (HRR) and left ventricular ejection fraction (LVEF) in DCM, treated with carvedilol.Methods: This is a multi center retrospective analysis conducted on all children with DCM (aged < 18 years) between 2013 and 2020, with LVEF < 40% and treated with carvedilol. Carvedilol was up titrated to the maximal tolerated dose or to 1 mg/kg/day. Echocardiographic data on left ventricular function and dimension were collected. The relationship between HRR and LVEF, left ventricular end-diastolic (LVEDd) and end-systolic diameter (LVESd) was assessed before and after HRR with carvedilol, using regression analysis.Results: 100 patients were enrolled (M: 51%; age 7 & PLUSMN; 8 years). The mean LVEF was 30.2 & PLUSMN; 10% before treatment and 43.7 & PLUSMN; 9.6% after treatment, at the maximum therapeutic dose (p < 0.0001). There was a positive relationship between HRR and increase in LVEF (R (2) = 0.06, p = 0.014). A HRR of > 20% correlated with an improvement in LVEF > 13%. At 3 years follow up, HRR demonstrated a significant reduction of LVESd (R2 = 0.1, p = 0.003) LVEDd (R2 = 0.07, p = 0.008) and LVEF recovery up to 15% (p < 0.0001). No deaths or heart transplant occurred during follow-up.Conclusion: This study demonstrates that HRR is safe and improvement in LVEF is related to the degree of HRR. The magnitude of LVEF improvement was enhanced by a major reduction in HR. It provides evidence that HRR could be used as a clinical marker to treat HF in children.