Abstract Body (Do not enter title and authors here): Background Individuals with 22q11 deletion syndrome have a mutation in the TBX1 gene which is associated with the formation of cardiac outflow tracts. Animal studies have shown that mice with TBX1 gene mutations have smaller left pulmonary arteries compared to wild type mice, defined by a reduced left pulmonary artery (LPA) to right pulmonary artery (RPA) ratio. A single study has shown this translates to humans with 22q11 and structurally normal hearts. We sought to determine if this is also true for patients with congenital heart disease and whether this finding has clinically significant links with reference to the need for increased intervention upon the LPA.
Method We performed a retrospective analysis of patients at our centre who underwent surgical repair of Tetralogy of Fallot, Truncus Arteriosus or Interrupted Aortic Arch between 2007 and 2022, with follow up to 2023. 134 patients were identified and were divided into two groups, those with 22q11 deletion syndrome (19 patients) and the control group (115 patients). The LPA to RPA ratio on initial and most recent echocardiogram, intervention on the LPA at initial surgery and subsequent reintervention on the LPA were compared between the two groups.
Results The 22q11 deletion and control group had a similar mean age at time of study 6.9±3.4 versus 5.9±3.8 years. Tetralogy of Fallot was overrepresented in the control group compared to the 22q11 deletion group (87.8% versus 42.1%). Patients with 22q11 deletion had a reduced LPA to RPA ratio compared to the control group on both the initial (0.84±0.17 versus 1.03±0.18; p<0.001) and most recent (0.76±0.17 versus 1.03±0.27, p=0.002) echocardiogram. Patients with 22q11 were more likely to have intervention on the LPA in their initial surgery compared to the control group (36% versus 8.7%, p = 0.003). There was no statistical differences between rates of LPA reintervention between the 22q11 deletion group and the control group (26% versus 10.7%; p=0.070).
Conclusion Patients with 22q11 deletion syndrome are more likely to have reduced LPA to RPA ratio and need intervention on the LPA at the initial surgery, despite Tetralogy of Fallot (the only of the three lesions known to be associated with LPA stenosis) being over represented in the control group. The most recent echocardiogram showed a reduced LPA to RPA ratio in the 22q11 group, so we suspect that whilst we demonstrated no difference in rates of reintervention, this could change with longer follow up.