Kathryn W. Holmes

Genome-wide association study identifies a susceptibility locus for thoracic aortic aneurysms and aortic dissections spanning FBN1 at 15q21.1

Although thoracic aortic aneurysms and dissections (TAAD) can be inherited as a single-gene disorder, the genetic predisposition in the majority of affected people is poorly understood. In a multistage genome-wide association study (GWAS), we compared 765 individuals who had sporadic TAAD (STAAD) with 874 controls and identified common SNPs at a 15q21.1 locus that were associated with STAAD, with odds ratios of 1.6–1.8 that achieved genome-wide significance. We followed up 107 SNPs associated with STAAD with P < 1 × 10−5 in the region, in two separate STAAD cohorts. The associated SNPs fall into a large region of linkage disequilibrium encompassing FBN1, which encodes fibrillin-1. FBN1 mutations cause Marfan syndrome, whose major cardiovascular complication is TAAD. This study shows that common genetic variants at 15q21.1 that probably act via FBN1 are associated with STAAD, suggesting a common pathogenesis of aortic disease in Marfan syndrome and STAAD.

Efficacy and Safety of Lovastatin Therapy in Adolescent Girls With Heterozygous Familial Hypercholesterolemia

Objective. The present study was designed to evaluate the lipid-altering efficacy, safety, and tolerability of lovastatin treatment in adolescent girls with heterozygous familial hypercholesterolemia. Methods. A total of 54 postmenarchal girls, aged 10 to 17 years, were enrolled in a 24-week, double-blind, randomized, placebo-controlled study. After a 4-week diet/placebo run-in period, patients were randomized to 1 of 2 groups: (1) treatment with diet plus lovastatin 20 mg/day for 4 weeks, followed by diet plus lovastatin 40 mg/day for 20 weeks, or (2) diet plus placebo for 24 weeks. Results. Baseline values of lipids, lipoproteins, and apolipoproteins (apo) were comparable between treatment groups. Lovastatin treatment was efficacious at reducing low-density lipoprotein cholesterol by 23% to 27%, total cholesterol by 17% to 22%, and apo B by 20% to 23% at weeks 4 and 24, respectively. Between-treatment group differences were not statistically significant for triglycerides, very-low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or apo A-I. Lovastatin was generally safe and well tolerated. There were no clinically significant alterations in vital signs (blood pressure and pulse rate), anthropomorphic measurements (height, weight, and BMI), hormone levels (luteinizing hormone, follicle-stimulating hormone, dehydroepiandrosterone sulfate, estradiol, and cortisol), menstrual cycle length, or tests of liver and muscle function. Conclusions. Lovastatin offers an efficacious and well-tolerated treatment option for improving lipid profiles in adolescent girls with familial hypercholesterolemia.

Impact of Image Analysis Methodology on Diagnostic and Surgical Classification of Patients With Thoracic Aortic Aneurysms

BACKGROUND For patients with thoracic aortic aneurysms (TAA), aortic size on imaging is widely used to guide clinical decision making. This study examined the impact of methodological variance on aortic quantification. METHODS We studied enrollees in the National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions. Aortic size on computed tomography was quantified by 2 linear methods; cross-sectional dimensions in axial (AX) and double oblique (DO) plane. Calculated area was compared to planimetry. Established cutoffs (area/height>10 cm2/m, diameter≥5 cm) for prophylactic TAA repair were used to compare surgical eligibility by each method. RESULTS Fifty subjects were studied. Aortic size differed between AX and DO at all locations (p≤0.001), with magnitude greatest at the sinotubular junction (4.8±1.1 vs 4.0±1.0 cm, p<0.001). The difference between AX and DO correlated with aortic angular displacement (r=0.37, p<0.01), which was threefold larger at the sinotubular junction (37±12 degrees) than the ascending aorta (12±5 degrees; p<0.001). At all locations, aortic area calculated using DO yielded smaller differences with planimetry than AX (p<0.05). DO and planimetry yielded equal prevalence (24%) of subjects eligible for prophylactic TAA repair based on area-height cutoff, whereas AX prevalence was higher (44%; p=0.006). Using a linear cutoff, AX yielded over a twofold greater prevalence of surgically eligible subjects (56%) than did DO (24%; p<0.001). CONCLUSIONS Established linear methods for aortic measurement yield different results that impact surgical eligibility. DO yielded improved agreement with planimetry and differed with AX in proportion to aortic geometric obliquity. Findings support DO measurements for imaging evaluation of subjects with TAA.

Heterotaxy syndrome: defining contemporary disease trends.

The purpose of this study was to define a population of visceral heterotaxy and to investigate the incidence of bacterial sepsis in the current era of universal pediatric pneumococcal immunization. Pediatric echocardiography and radiology databases, along with electronic medical records, were searched for patients followed-up since birth between 1999 and 2009 with either asplenia or polysplenia and cardiac anatomy consistent with heterotaxy syndrome. A total of 29 patients were identified. Seven patients (24%) had a total of 8 sepsis events, and 6 patients (86%) developed sepsis while taking appropriately prescribed antibiotic prophylaxis. Of the patients with sepsis, 5 had polysplenia and 2 had asplenia. Sixty-two percent of sepsis events were nosocomially acquired. No cases of pneumococcal sepsis occurred after the introduction of the conjugated pneumococcal vaccination to the pediatric vaccination schedule. Bacterial sepsis was associated with a 44% mortality rate. An unexpected finding in 3 patients with visceral heterotaxy, asplenia, and an interrupted inferior vena cava (IVC) as the only anomaly on echocardiography was associated intestinal malrotation. Children with visceral heterotaxy remain at significant risk of life-threatening bacterial infection. In addition, the finding of interrupted IVC on echocardiography should prompt screening for intestinal malrotation, even in the absence of additional structural heart disease.

The National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC): results from phase I and scientific opportunities in phase II.

BACKGROUND Genetically triggered thoracic aortic conditions (GenTACs) represent an important problem for patients and their families. Accordingly, the National Heart, Lung, and Blood Institute established the first phase of its national GenTAC Registry in 2006. ENROLLMENT AND DIAGNOSES Between 2007 and 2010, 6 enrolling centers established the GenTAC I Registry consisting of 2,046 patients (Marfan syndrome 576 [28.2%], bicuspid aortic valve disease 504 [24.6%], aneurysm or dissection age <50 years 369 [18%], and others). Biologic samples for DNA analyses (white blood cells or saliva) are available in 97%, and stored plasma is available in 60% of enrollees. RESULTS Initial scientific inquiry using the GenTAC Registry has included validation studies of genetic causes for aortic syndromes, potential usefulness of transforming growth factor beta (TGFB) blood levels in Marfan subjects, and current surgical approaches to ascending aortic conditions. FUTURE OPPORTUNITY The second phase of GenTAC will allow biannual follow-up of GenTAC I enrollees for up to 9 years, enrollment of an additional 1,500 subjects, further integration of imaging findings with clinical and genetic data through utilization of an imaging core laboratory, important validation of phenotype-genotype correlations through a phenotyping core laboratory, and integration of a scientific advisory committee to help define the full range and depth of the Registrys scientific capabilities. The registry resources are available to the external scientific community through an application process accessible at https://gentac.rti.org.

Long-term implications of emergency versus elective proximal aortic surgery in patients with Marfan syndrome in the Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions Consortium Registry.

OBJECTIVE Patients with Marfan syndrome with aortic root aneurysms undergo elective aortic root replacement to avoid the life-threatening outcomes of aortic dissection and emergency repair. The long-term implications of failed aortic surveillance leading to acute dissection and emergency repair are poorly defined. We compared the long-term clinical courses of patients with Marfan syndrome who survive emergency versus elective proximal aortic surgery. METHODS The Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions Registry is a National Institutes of Health-funded multicenter database and biorepository that enrolls patients with genetically triggered thoracic aortic aneurysms. Of the 635 patients with Marfan syndrome enrolled as of March 2011, 194 had undergone proximal aortic replacement. Patients were grouped according to emergency (n = 47) or elective (n = 147) status at the time of surgery. RESULTS Patients in the emergency group were more likely to have incomplete proximal aortic resection; 83% of emergency procedures included aortic root replacement, compared with 95% of elective procedures. At long-term follow-up (mean, >6 years), the emergency group had a higher incidence of chronic dissection of the distal aorta and significantly larger diameters in distal aortic segments than elective patients. Patients in the emergency group had undergone more operations (1.31 vs 1.11 procedures/patient; P = .01) and had lower activity scores on a health-related quality of life survey. CONCLUSIONS For patients with Marfan syndrome, failed aortic surveillance and consequent emergency dissection repair have important long-term implications with regard to the status of the distal aorta, need for multiple procedures, and quality of life. These findings emphasize the importance of aortic surveillance and timely elective aortic root aneurysm repair for patients with Marfan syndrome.

The Need for Standardized Methods for Measuring the Aorta Multimodality Core Lab Experience from the GenTAC Registry

OBJECTIVES This study sought to evaluate variability in aortic measurements with multiple imaging modalities in clinical centers by comparing with a standardized measuring protocol implemented in a core laboratory. BACKGROUND In patients with aortic disease, imaging of thoracic aorta plays a major role in risk stratifying individuals for life-threatening complications and in determining timing of surgical intervention. However, standardization of the procedures for performance of aortic measurements is lacking. METHODS To characterize the diversity of methods used in clinical practice, we compared aortic measurements performed by echocardiography, computed tomography (CT), and magnetic resonance imaging (MRI) at the 6 GenTAC (National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions) clinical centers to those performed at the imaging core laboratory in 965 studies. Each center acquired and analyzed their images according to local protocols. The same images were subsequently analyzed blindly by the core laboratory, on the basis of a standardized protocol for all imaging modalities. Paired measurements from clinical centers and core laboratory were compared by mean of differences and intraclass correlation coefficient (ICC). RESULTS For all segments of the ascending aorta, echocardiography showed a higher ICC (0.84 to 0.93) than CT (0.84) and MRI (0.82 to 0.90), with smaller mean of differences. MRI showed higher ICC for the arch and descending aorta (0.91 and 0.93). In a mixed adjusted model, the different imaging modalities and clinical centers were identified as sources of variability between clinical and core laboratory measurements, whereas age groups or diagnosis at enrollment were not. CONCLUSIONS By comparing core laboratory with measurements from clinical centers, our study identified important sources of variability in aortic measurements. Furthermore, our findings with regard to CT and MRI suggest a need for imaging societies to work toward the development of unifying acquisition protocols and common measuring methods.

Aortic Complications Associated With Pregnancy in Marfan Syndrome: The NHLBI National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC)

Background The risk of aortic complications associated with pregnancy in women with Marfan syndrome (MFS) is not fully understood. Methods and Results MFS women participating in the large National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC) were evaluated. Among 184 women with MFS in whom pregnancy information was available, 94 (51%) had a total of 227 pregnancies. Among the women with pregnancies, 10 (10.6%) experienced a pregnancy‐related aortic complication (4 type A and 3 type B dissections, 1 coronary artery dissection, and 2 with significant [≥3 mm] aortic growth). Five of 7 aortic dissections, including all 3 type B, and the coronary dissection (75% of all dissections) occurred in the postpartum period. Only 5 of 8 women with pregnancy‐associated dissection were aware of their MFS diagnosis. The rate of aortic dissection was higher during the pregnancy and postpartum period (5.4 per 100 person‐years vs 0.6 per 100 person‐years of nonpregnancy; rate ratio, 8.4 [95% CI=3.9, 18.4]; P<0.0001). Conclusions Pregnancy in MFS is associated with an increased risk of aortic dissection, both types A and B, particularly in the immediate postpartum period. Lack of knowledge of underlying MFS diagnosis before aortic dissection is a major contributing factor. These findings underscore the need for early diagnosis, prepregnancy risk counseling, and multidisciplinary peripartum management.

GenTAC registry report: Gender differences among individuals with genetically triggered thoracic aortic aneurysm and dissection:

Previous data suggest women are at increased risk of death from aortic dissection. Therefore, we analyzed data from the GenTAC registry, the NIH‐sponsored program that collects information about individuals with genetically triggered thoracic aortic aneurysms and cardiovascular conditions. We performed cross‐sectional analyses in adults with Marfan syndrome (MFS), familial thoracic aortic aneurysm or dissection (FTAAD), bicuspid aortic valve (BAV) with thoracic aortic aneurysm or dissection, and subjects under 50 years of age with thoracic aortic aneurysm or dissection (TAAD <50 years). Women comprised 32% of 1,449 subjects and were 21% of subjects with BAV, 34% with FTAAD, 22% with TAAD <50 years, and 47% with MFS. Thoracic aortic dissections occurred with equal gender frequency yet women with BAV had more extensive dissections. Aortic size was smaller in women but was similar after controlling for BSA. Age at operation for aortic valve dysfunction, aneurysm or dissection did not differ by gender. Multivariate analysis (adjusting for age, BSA, hypertension, study site, diabetes, and subgroup diagnoses) showed that women had fewer total aortic surgeries (OR = 0.65, P < 0.01) and were less likely to receive angiotensin converting enzyme inhibitors (ACEi; OR = 0.68, P < 0.05). As in BAV, other genetically triggered aortic diseases such as FTAAD and TAAD <50 are more common in males. In women, decreased prevalence of aortic operations and less treatment with ACEi may be due to their smaller absolute aortic diameters. Longitudinal studies are needed to determine if women are at higher risk for adverse events.

Trisomy 18 and Complex Congenital Heart Disease: Seeking the Threshold Benefit

A prenatal diagnosis of ductal-dependent, complex congenital heart disease was made in a fetus with trisomy 18. The parents requested that the genetic diagnosis be excluded from all medical and surgical decision-making and that all life-prolonging therapies be made available to their infant. There was conflict among the medical team about what threshold of neonatal benefit could outweigh maternal and neonatal treatment burdens. A prenatal ethics consultation was requested.