Updated Cardiac Description in Loeys Dietz Syndrome. G. L. Oswald1, E. M. Reynolds1, H. C. Dietz1,2, J. P. Habashi3, genTAC consortium investigators 1) Genetics, Johns Hopkins, Baltimore, MD; 2) Howard Hughes Medical Institute, Bethesda, MD; 3) Pediatric Cardiology, Johns Hopkins University, Baltimore, MD.

   Loeys-Dietz syndrome (LDS) is an autosomal dominant connective tissue disorder characterized by a triad of aortic root enlargement with arterial tortuosity, hypertelorism and bifid uvula. In the original description in 2005, an increased prevalence of cardiac features were noted including patent ductus arterioles (PDA), patent foramen ovale (PFO)/atrial septal defect (ASD), bicuspid aortic valve (BAV), and ventricular septal defect (VSD). The purpose of this study was to analyze the 73 patients with LDS with confirmed TGFBR1 or 2 mutations in the GenTAC (National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions) registry, and compare the findings to the 695 patients with a diagnosis of Marfan syndrome (MFS) confirmed by the Ghent criteria. The average age of diagnosis for LDS was 17.1 and 68.5% of patients were diagnosed at an age21 years. In LDS, the prevalence of PDA (11.0%) and PFO/ASD (26.0%) was significantly greater than reported in MFS (0.1%, 2.0%, respectively; p0.0001). The prevalence of BAV was two fold higher in LDS (8.2%) versus MFS (3.9%) and the prevalence of any aortic regurgitation (AR) was also significantly greater (46.6% v. 27.1%; p0.001). Mitral valve prolapse (MVP) was not significantly different between LDS 32.9%) and MFS (26.6%), however the prevalence of greater than trace mitral regurgitation (MR) was greater in MFS (54.0%) as compared to LDS (30.1%; p0.0001. Aortic dimensions prior to any aortic surgery were available in 33 LDS patients and revealed that 91% of LDS patients had an aortic root z score 2 and 79% had a z score3. Furthermore, only 39% had an ascending aortic z score 2 and in only 18%, the z score was 3. No patients had a dilated ascending aorta in the absence of aortic root dilation. Analysis of the GenTAC database confirms the increased prevalence of certain congenital heart lesions in patients with LDS particularly in comparison to MFS. The area of aortic enlargement in LDS, as in MFS, shows a strong predilection for the root. The presence of these abnormalities should raise the consideration of LDS in patients with aortic aneurysm.

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