Aortic Dissection in BAV Patients: The IRAD Experience and Beyond

Eduardo Bossone, MD, Ph.D, FESC, FACC Cardiology Division - Heart Dept.

University of Salerno, Italy

I have no financial relationships to disclose.

Erbel R. ESC Guidelines on the Diagnosis and Treatment of Aortic Diseases. EHJ 2014.. Michelena et al.JAMA.2011; 306:1104-1112.- Michelena H et al. Circulation.2014;129:2691-2704.

Davies RR et al.Ann Thorac Surg 2007;83:1338–1344.- Ando M et al.Cardiovasc Surg 1998;6:629–634.

• BAV is the most common congenital cardiac defect, with a prevalence at birth of 1–2%. Males

are more often affected than females, with the ratio ranging from 2:1 to 4:1. • Cumulative incidence of 6% of Type A AD in untreated patients with BAV and aortic dilation

over a mean follow-up of 65 months has been reported. However in the current era of early preventive surgery this is difficult to assess. There are no reliable historical data.

• The prevalence of BAV ranges from 2–9% in Type A AD and 3% in Type B AD, both only slightly higher than the prevalence of BAV in the general population (1–2%).

Background

Mackram F Eleid et al. Heart 2013;99:1668–1674

Michelena H et al. Circulation.2014;129:2691-2704

Risk of Aortic Surgery After Definite Bicuspid Aortic Valve Diagnosis

Michelena et al.JAMA.2011; 306:1104-1112

Kaplan-Meier risk of AVR and aorta surgery (all causes) 25 years after definitive diagnosis of BAV. After 25 years of follow-up, the risk of undergoing AVR doubles that of aortic surgery.

IRAD represents an investigational collaboration that has collected information on unselected consecutive cases of AAD from 30 aortic referral centers in 10 countries since January 1, 1996. Patients with AAD were identified either prospectively at presentation or retrospectively by searching hospital discharge diagnosis records and/or surgery, pathology, and imaging databases. Diagnosis was based on imaging, surgical visualization, or on autopsy. Patients’ data were collected using standardized forms entered into an online database maintained at the University of Michigan and reviewed for face validity and completeness.

International Registry of Acute Aortic Dissections

http://www.iradonline.org/irad.html

Aortic Diameter ≥5.5 cm Is Not a Good Predictor of Type A Aortic Dissection

Distribution of aortic size at time of presentation with acute type A aortic dissection (cm)

Pape L A et al. Circulation. 2007;116:1120-1127

Shaded bars indicate 59% of patients with diameters< 5.5 cm.

•Patients with Marfan Syndrome were excluded from the analysis. •The prevalence of Type A and Type B AAD differed between groups (p<0.001)

Chi-Squares analysis or Fischer’s Exact Test where appropriate was used to compare categorical variables. Continuous variables were analyzed by students t-test or non-parametric test of medians for variables with skewed distributions.

Aortic Diameters: BAV vs TAV

BAV TAV

The dissected aorta in BAV and TAV patients

Limitations and strengths

• Although our findings were significant, reasonable, and consistent with other studies, the total number of BAV patients in

our study was small. As a consequence we were not able to further characterize interesting subgroups of BAV patients such

as those with age <40 years or type B dissection. Aortic diameters were not available prior to dissection for either group.

• Thus, conclusions and implications related to the larger aortic dimension of BAV vs. TAV patients should be taken with

caution: a larger aortic diameter after dissection does not necessarily imply a larger aortic diameter prior to dissection and

it cannot be excluded that altered biomechanical properties of the BAV vessel may have resulted in a greater acute increase

in aortic diameter at the time of aortic wall laceration.

• Nevertheless, other investigators in smaller study populations have already reported the observation of a larger aorta in the

BAV dissected patients, and our registry data appear to confirm this observation

On behalf of IRAD Investigators

Conclusions

• BAV individuals with AAD presented with distinct morphological and clinical characteristics: they were on average 10

years younger than TAV subjects, had less hypertension and diabetes but more known aortic aneurysm and previous

aortic valve replacement surgery.

• The dissected aorta of BAV patients was larger than that of TAV patients at the aortic root, and was more often

associated with aortic valve insufficiency, pericardial effusion and arch vessel involvement.

• Despite its characteristic as a disease of the proximal aorta, 20 patients with BAV presented with type B dissection.

BAV patients with type A AAD underwent more root replacement operations. Despite their younger age, BAV patients

did not enjoy better hospital outcomes.

• Additional research into risk factors for acute dissection in BAV patients, including aortic wall stress, genetic markers,

and novel imaging is warranted to optimize timing of prophylactic aortic resection in this population.

Coarctation of the aorta, systemic hypertension, family history of dissection, or increase in aortic diameter .>.3 mm/year (on repeated measurements using the same imaging technique, measured at the same aortic level, with side-by-side (comparison and confirmed by another technique).