Cardiomyopathy Due to Propionic Acidemia: Clinical Features and Therapeutic Implication

Abstract

<h3>Purpose</h3> Propionic acidemia (PA) is an organic acidemia caused by an inherited deficiency of the enzyme Propionyl CoA carboxylase. Cardiac involvement as QTc interval prolongation and heart muscle disease, typically as dilated cardiomyopathy, is known. To date, the characteristics of cardiomyopathy (CMP) and its treatment are poorly understood. <b>Aims</b>: define cardiovascular (CV) profile in patients with PA and response to CV therapy. <h3>Methods</h3> Single center retrospective analysis of patients with PA followed at Bambino Gesù Children's Hospital in Rome. Each patient's clinical, CV data (ECG, echocardiogram, cardiac magnetic resonance [MRI], NTproBNP, troponinT) and CV therapy were collected: at the first CV contact, at CMP onset, after 1 year and at last follow-up. Death, CV death, CV involvement, liver transplantation (LT) were considered as clinical outcomes. <h3>Results</h3> 26 patients (20 M) were included. Mean age at PA diagnosis was 83 days and at first CV contact was 8.48 ± 6.4 yrs. Over the time, 42% reported CV manifestation (38.5% CMP), 23% underwent LT, 46% died. Mean age at death was 8 ± 8 years. Mean age at CMP onset was 12 ± 6 years. 1 patient experienced sudden aborted cardiac death (SCD - defibrillated VF) at the age of 7. QTc interval was increased (>460ms) in the 43% (mean QTc 452 ms±43 ms). 8 cardiac MRIs were performed in 7 pts. MRI data showed LV dilation and eccentric remodelling: average indexed telediastolic volume 107 ml/m2; average indexed LV mass 71 g/m2. In no case were significant areas of late myocardial enhancement after contrast medium infusion. Therapeutically, 100% of patients followed for CMP were treated with therapeutic dose of ACE inhibitors, 70% with beta blocker, 80% with antialdosteronic agents, and 30% with ivabradine. After 1 year of treatment, LVEF increased from a mean value of 35.9% (± 11) to 52% (± 2.7; p< 0.05). 3 patients underwent LT for severe LV disfunction. They were all treated with maximal CV therapy before LT. At last follow up, 12 mos from LT for the first patient and 18 mos for the second, LVEF reached 47% and 54% from 35% at baseline. The third patient died at 3 months from LT for pneumonia. <h3>Conclusion</h3> CMP and SCD affect the prognosis of PA, especially in patients without metabolic decompensation. CV therapy can improve cardiac function. LT can be considered also in case of severe impaired LV function, after heart failure treatment has been optimized.