161 Characterising left ventricular systolic dysfunction in sickle cell disease

Background Sickle cell disease (SCD) is an inherited haemoglobinopathy characterised by recurrent vaso-occlusive crises and chronic haemolytic anaemia. Amongst the cardiac complications related to SCD, left ventricular systolic dysfunction (LVSD) is an uncommon, poorly characterised, but life-threatening complication. Purpose To characterise using cardiac MRI (CMR) the varying phenotypes of LVSD complicating SCD. Methods We conducted a retrospective evaluation of 20 SCD patients with LVSD (LVEF <55%) identified by transthoracic echocardiography (TTE), who were attending a specialist cardiology-haemoglobinopathy clinic between April-December 2023. We excluded patients who had not had a CMR [n=4], with normal LV function on CMR [n=4] and alternative explanation for LVSD [n=1]. We collected demographics, clinical data and imaging data from TTE and CMR, including ventricular dimensions and function, presence of Late Gadolinium Enhancement (LGE) and parametric mapping (T1, T2, T2*). Results The data of 11 patients are shown in tables 1 and 2. We identified 3 different phenotypes of LVSD: non-ischaemic dilated cardiomyopathy (NI-DCM) [n=8], ischaemic dilated cardiomyopathy (I-DCM) [n=2] and iron-overload cardiomyopathy [n=1]. Figure 1 shows CMR imaging of selected patients from each subgroup. Significant co-morbidities in the NI-DCM cohort included hypertension (HTN) (50%) and renal impairment (25%). We identified significant LV dilatation, elevated T1 values and high rates of non-ischaemic LGE in this subgroup. Despite high ferritin levels, there was no cardiac iron overload, however 75% (n=6) had liver iron overload. In the I-DCM cohort, we identified two patients with extensive myocardial infarcts seen on CMR, severe LV dilatation and significant LV impairment but no epicardial coronary artery disease on cardiac CT. Finally, we identified one patient with iron-overload cardiomyopathy (cardiac T2* 7 ms, T1 598 ms) and severe LVSD. She had been on regular top-up transfusions for more than 10 years, with poor chelation compliance. Rapid deterioration of LV function was noted between TTE and CMR dates. Discussion Recognised, common cardiac complications in adults with SCD include LV diastolic dysfunction in the setting of chronic anaemia, usually resulting in LV dilatation and eccentric hypertrophy. Our NI-DCM group may present a late consequence of these pathophysiologic changes, in the setting of HTN and CKD which have previously been reported to be associated with LVSD. Interestingly, we identified significant LV fibrosis (high T1, LGE) which has not been previously reported in SCD. We describe two patients with ischaemic cardiomyopathy with no epicardial coronary disease, likely due to microvascular infarction. One patient succumbed to heart failure 3 years from diagnosis, the other being considered for device therapy. These outcomes highlight the dire consequences of this complication. Finally, we describe a patient with severe LVSD and severe cardiac iron overload. Iron overload cardiomyopathy is exceedingly rare in SCD (<3%), however remains an important consideration in patients with unexplained LVSD in the context of recurrent transfusions and poor compliance with chelation and can result in rapid deterioration and mortality if untreated. Conclusion To our knowledge, this descriptive study is the first one to characterise the aetiology of LVSD in SCD. Despite a small patient cohort, we have identified 3 different phenotypes with NI-DCM being the most common. We emphasise the vital role CMR in phenotyping LVSD in SCD and we believe this study supports the undertaking of prospective studies to further delineate the underlying pathophysiology of these very serious complications of SCD. Conflict of Interest None