Aims This single centre observational study looks into the incidence of intestinal malrotation in the population with left or right atrial isomerism; and at practice regarding screening for malrotation and intervention on asymptomatic patients.

Methods A prospective cardiac database identified all patients with a diagnosis of left or right atrial isomerism born between 01/01/2001–01/10/2016. Details of their symptoms, imaging, investigation and surgical intervention were then retrospectively obtained from the patient electronic records.

Results Over the 16 year study period, 33 patients with isomerism were identified. Of these, 11 were found to have intestinal malrotation, which was seen in 32% of patients with right atrial isomerism and 36% with left atrial isomerism. 39% of female patients were affected in comparison to 27% of male patients.

16/33 patients had a barium meal to assess intestinal rotation; of which 7/16 patients showed symptoms and so were ‘investigated’; whereas 9/16 were asymptomatic and were ‘screened’. The incidence of malrotation was 71% in the investigated symptomatic group and 68% in the screened asymptomatic group.

From the whole cohort, 9/33 had gastrointestinal symptoms consistent with malrotation; and subsequently 5/9 had malrotation on imaging. Malrotation was picked up via screening in 6/24 of the asymptomatic group; although not all asymptomatic patients were screened. There is no significant difference in incidence of malrotation between symptomatic and asymptomatic patients (p=0.12) using Fisher’s exact test to compare the two groups.

Conclusions There are comparable rates of malrotation in both left and right atrial isomerism. From the data obtained in this study, the presence or absence of gastrointestinal symptoms cannot be used to determine the presence of underlying malrotation.

Although not all malrotation will require surgical intervention, it seems that further investigation and routine screening for intestinal malrotation could be justified.