Left ventricular non-compaction in patients with β-thalassemia: structural remodeling or cardiomyopathy?

Abstract

In the era of the modern imaging techniques, cardiac magnetic resonance (CMR) has become the key component to confirm or rule out left ventricular non-compaction cardiomyopathy (LVNC), as echocardiography cannot always allow proper visualization of the apex and apical segments [1]. Although initially described and recognized as a rare entity in the general population, after the first report of LVNC in identical twins with β-thalassemia major [2], more and more studies aimed to explore the prevalence and evolution of LVNC in this setting. In this issue of Internal and Emergency Medicine, Bonamini and co-authors [3] add certain interesting findings to the growing literature on the prevalence and the disease progression of the LVNC in patients with β-thalassemia. In this elegant study, in a 7-year period, 560 patients with thalassemia major or intermedia underwent assessment of left ventricle structure, dimensions, and systolic function with CMR, as this diagnostic tool is utilized to this population to evaluate heart iron load and cardiac function. For the assessment of the presence of LVNC, the modified Petersen and the Jacquier methods were applied and the cases which fulfilled the following three criteria were considered positive: (i) diastolic Mnon-compacted/Mtotal percentage > 25%, (ii) diastolic Mnon-compacted/BSA > 15 g/m2 and (iii) diastolic non-compacted/compacted myocardium ratio of > 2.5 in at least one of the segments, excluding the apical. According to the above-mentioned criteria, a diagnosis of LVNC was determined in 44 patients (7.9%). Interestingly, intracardiac thrombi were not detected with CMR in none of the 560 patients. Moreover, no relationship was found between splenectomy, iron chelation therapy and hematological parameters (serum ferritin and total hemoglobin) with the presence of LVNC, while T2*, time for the evaluation of cardiac and liver siderosis, similarly did not depict any significant difference between β-thalassemia patients with and without LVNC. It should be also emphasized that no adverse events occurred in patients with thalassemia and LVNC during follow-up. In line with this observation, no further dilatation of the left ventricle or significant differences of its systolic function or LVNC mass changes were detected by CMR overtime. The main finding of the present study consists of the high prevalence of LVNC in β-thalassemia patients, which was 7.9%. This rate is pretty higher as compared with previous reports from echocardiographic studies in the general adult population where the relevant prevalence was between 0.014 and 1.3% [4]. However, a prevalence as high as 13.2% has been reported previously with CMR studies this time, although as it was mentioned by the authors themselves an overestimation could have accounted for this finding [5]. Concerning the methodology applied in the work of Bonamini and co-authors, the study population underwent CMR assessment in the context of a regular control program in a population of patients with β-thalassemia. Nevertheless, some patients may have been selected for measurement based on pre-existing cardiac risk factors. If such factors are potentially linked to LVNC occurrence, this may offer a plausible explanation for the high prevalence of LVNC depicted in this study. One of the major strengths of this observational study consists of the high number of thalassemia patients included, namely 560, which is the highest recorded for this disorder. It should be also mentioned that the stringent CMR methodology adopted enhances its accuracy. Visual analysis and measurements of CMR parameters were performed by experienced operators. For instance, a more restrictive modification of the original criterion or the ratio of noncompacted to compacted myocardium during the diastole from 2.3 to 2.5 was used [1]. In addition, the criterion of diastolic Mnon-compacted/BSA > 15 g/m2, which was proposed * George Lazaros [email protected]