Study Suggests TEVAR May Benefit Some Patients With Uncomplicated Acute Type B Aortic Dissection

 

November 29, 2016—Findings from a single-center, retrospective study that sought to determine the predictors of intervention and mortality in patients with uncomplicated acute type B aortic dissection (uATBAD) were published by Hunter M. Ray, MD, et al in the Journal of Vascular Surgery (JVS; 2016;64:1560–1568).

Patients with uATBAD have historically been managed with medical therapy, but recent studies suggest that high-risk patients may benefit from thoracic endovascular aortic repair (TEVAR).

The investigators concluded that patients with the following high-risk criteria may benefit from TEVAR: (1) aortic diameter > 44 mm; (2) age > 60 years on admission; and (3) a false lumen (FL) diameter > 22 mm and maximum aortic diameter > 44 mm on admission. More studies are needed to further define patients at highest risk and, thus, most likely to benefit from early intervention, advised the investigators in JVS.

Ali Azizzadeh, MD, the study’s lead investigator, commented to Endovascular Today, “The historical in-hospital mortality rate for patients with uATBAD in our series was 1.9%, while the 5-year survival for that cohort with medical therapy was 76.6%. In other words, close to 1 in 4 patients with uATBAD are dying during follow-up with medical therapy alone. This leaves a significant opportunity for improvement in care with newer modalities such as TEVAR. This series confirms that patients with dilated aortas on presentation may benefit from prophylactic TEVAR.” Dr. Azizzadeh is Professor and Chief, Division of Vascular and Endovascular Surgery at the University of Texas Health Science Center at Houston in Houston, Texas.

For the study, the investigators reviewed all patients admitted with uATBAD from 2000 to 2014, and those with CTA imaging were included. Using multiplanar reconstruction, a specialized cardiovascular radiologist obtained double orthogonal oblique measurements. Maximum aortic diameter, proximal descending thoracic aorta FL diameter, and area were recorded. Outcomes, including the need for intervention and mortality, were tracked over time. Data were analyzed by stratified Kaplan-Meier and multiple Cox regression analysis using SAS v 9.4 (SAS Institute, Inc.).

During the study period, 294 patients with uATBAD were admitted, and 156 had admission CTA available for analysis (mean age, 60.6 years [± 13.6 years]; 60% were male). Average follow-up was 3.7 years (interquartile range, 2.1–6.9 years).

A stratified analysis demonstrated the most sensitive cutoff for mortality was aortic diameter > 44 mm (P < .01), which appeared to be a threshold effect with minimal additional information added by finer size stratification. FL diameter did not predict mortality (P = .36), while intervention-free survival appeared to decrease over the range of diameters from 35 to 44 mm (P < .01).

FL diameter > 22 mm was associated with decreased intervention-free survival (P < .04). Age > 60 years on admission also demonstrated decreased survival compared with those aged ≤ 60 years (P < .01).

Diameter > 44 mm persisted as a risk factor for mortality (hazard ratio [HR], 8.6; P < .01) after adjustment for diabetes (HR, 6.7; P < .01), age (HR, 1.06 per year; P < .01), history of stroke (HR, 5.4; P < .01), connective tissue disorder (HR, 2.3; P < .01), and syncope on admission (HR, 9.5; P < .04).

The 1-, 5-, and 10-year intervention rates for patients with admission aortic diameter > 44 mm were 18.8%, 29.5%, and 50.3%, respectively, compared with 4.8%, 13.3%, and 13.3% in patients with aortic diameter ≤ 44 mm (P < .01), reported the investigators in JVS.

In an accompanying editorial by Richard P. Cambria, MD, and Mark F. Conrad, MD, of Massachusetts General Hospital in Boston, Massachusetts (JVS; 2016;64:1558–1559), they stated that the present study is an important one, with data consistent with their own single-center study. Drs. Cambria and Dr. Conrad noted that although the investigators acknowledged problems with retrospective studies, the current analysis may reflect referral bias and the study endpoint may lack precision. However, Drs. Cambria and Conrad concluded, “Irrespective of such limitations, the Houston data verifies the intuitively logical proposition that dilated aortas are more likely to develop, and require interval treatment for, aneurysm of chronic dissection etiology."

 

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