In patients undergoing thoracic endovascular aortic repair, procedural techniques may influence aortic remodeling and clinical outcomes after intervention.
Researchers conducted a retrospective review using data from 60 patients who underwent thoracic endovascular aortic repair (TEVAR) for treatment of complicated type B acute aortic dissection (n = 29) or chronic aortic dissection (n = 31). Acute dissection was defined as 14 days or less after the onset of symptoms, and chronic dissection was defined as at least 14 days from symptom onset. The mean age of the cohort was 69 years, and 40 patients were men. The minimum follow-up for each case was 3 years.
The goal of the study was to “retrospectively evaluate the procedural factors that may affect morphological changes of type B [acute aortic dissection] and [chronic aortic dissection] after TEVAR, as well as endoleak development and clinical outcome,” the researchers wrote.
The researchers used CT to assess true lumen, false lumen and total aortic short-axis diameters. They also analyzed six procedural factors in relation to aortic remodeling and outcomes: balloon dilation after stent graft deployment; covering of the left subclavian artery; embolization of the left subclavian artery; length of covered thoracic aorta; number of stent grafts implanted; and stent graft oversizing.
One hundred stent grafts were implanted from November 2009 to January 2011 (Thoracic Excluder Graft, W.L. Gore & Associates; Talent LPS, Medtronic; Valiant-Captivia, Medtronic; Zenith TX, Cook Medical; Relay, Bolton Medical). Clinical success was achieved in all patients with chronic dissection and 93.1% with aortic dissection. Endoleak occurred in 28% of patients, including two type I and six type II leaks in the acute dissection group and one type I and eight type II leaks in the chronic dissection group.
Among patients with acute dissection, true lumen diameter increased over time after treatment, from a mean of 20.4 mm to 28 mm at 36 months (P = .02), whereas false lumen diameter decreased from 9.1 mm to 5 mm (P = .01). The total maximum diameter of the aorta did not change at or below the level of the stent graft, but did increase above the graft, from 31.5 mm to 35.5 mm (P = .05). Among patients in with chronic dissection, the researchers observed no significant changes in true lumen, false lumen or total aortic diameter at all levels. The data revealed a correlation between the decreased false lumen diameter observed in the acute dissection group with increased false lumen thrombosis compared with the chronic dissection group (95% vs. 70%; P < .01).
Intentional occlusion of the left subclavian artery was performed in 48% of the acute dissection group and 61% of the chronic dissection group. Results of univariate analyses indicated a protective effect from left subclavian artery embolization against endoleaks among patients with acute dissection (P = .04), but not those with chronic dissection (P = .39). Multivariate analysis yielded no associations between covering or embolization of the left subclavian artery and major adverse events, death or aortic remodeling.
Sixty-two percent of patients in the aortic dissection group and 58% in the chronic dissection group had stent graft dilation. The researchers observed no significant associations between stent graft dilation and the rate of endoleak in either group. At 36 months, dilation was associated with improved false lumen thrombosis in the acute dissection group, according to univariate analysis (P = .031); however, dilation did not influence risk for major adverse events or endoleak, according to multivariate analysis (P = .754). In addition, there was no association between stent graft dilation and major adverse events, endoleak or false lumen thrombosis in the chronic dissection group.
“Aortic remodeling after TEVAR can be associated with the characteristics of the dissection and the procedural technique,” the researchers concluded. “According to the type of aortic dissection, different techniques such as postdilation, embolization of the [left subclavian artery] and distal extension of the stent graft may be considered.” – by Adam Taliercio
Disclosure: One researcher reports serving as a consultant and on the scientific advisory board for Bard, and receiving honoraria from Boston Scientific, Cook Medical, Marvao Medical, Medtronic, Optimed and Straub Medical.