Comparison Of Mid-term Clinical Outcome Between Patients With Type B Aortic Dissection Treated By Tevar Or Medical Treatment

Background: Aortic dissection results when blood separates the layers ofaortic wall, usually through a tear in the intima, the layer that is in directcontact with the flow of blood. Two classifications of aortic dissection arewidely used: The DeBackey classification, which includes3types (types1to3), and the Stanford classification, which includes2types, A and B.Type Bincludes cases in which the descending thoracic aorta is involved, with orwithout proximal or distal extension. Most early deaths from all types of aorticdissection are due to rupture of the aorta into the pleural cavity or pericardium.Death may also occur due to the obstruction of the origin of the coronaryartery, brachiocephalic artery, or visceral arteries by the dissecting hematoma.Traditional management of patients with aortic dissection includes bothmedical and surgical. Most Stanford type B acute aortic dissections aremanaged medically. However, in complicated type B acute dissection such asthose with rupture, impending rupture, end-organ ischemia, surgery ismandatory, although its outcome is poor. Moreover, aneurismal enlargement inthe chronic phase of dissection is another concern because it necessitates theuse of extended graft replacements for thoracic and abdominal lesions.Surgical results of these procedures have improved markedly, but mortalityand morbidity remain high. In1999, the concept of endovascular stent–graftclosure of the proximal entry tear was introduced as a novel treatment optionfor patients with type B-AD. It is less invasive, and initial results from severalstudies suggest that it may reduce the rates of mortality and morbidity and ithas been gaining space in this field thanks to its less-invasive nature whencompared to surgery, and after the demonstration in the first series of a highincidence of false lumen late thrombosis. TEVAR(Thoracic EndovascularAortic Repair) as an option for patients with type B aortic dissection is considered life-saving, although its role in treating dissection is unknown.Objective: The goal of this study was to describe mid-term survival ofpatients with descending thoracic aortic aneurysms after medical treatmentand endovascular repair (TEVAR).Methods: The study consisted of98patients with type B aortic dissectionfrom our hospital in China from January2001to October2012.The mostcommonly observed comorbidity was hypertension, which was observed in85patients, followed by cerebrovascular disease in6patients, cardiovasculardisease in6patients, diabetes mellitus in5patients. In our study population,no patients were determined to exhibit Marfan’s syndrome or iatrogenicdissection, but2traumatic dissection. In total, there were62patients in theTEVAR group and36patients in the medical therapy group.The TEVARgroup included55men and7women with an average age of49±11years(range:29–78years).And the medical therapy group included31men and5women with an average age of53±11years (range:27–79years). With regardto antihypertensive therapy, patients received β-blockers concurrently withadditionalα-blockers and angiotensin-converting enzyme inhibitors asappropriate. While maintaining adequate urine production, blood pressure wascontrolled with a target systolic blood pressure of120mm Hg. The TEVARwas performed in a laboratory with imaging capabilities that included digitalangiography for catheterization maneuvers. Selection of the stent graft wasbased on careful assessment of the pathology by reconstruction and analysis ofthe diagnostic images. The procedures were always performed under generalanesthesia and controlled hypotension (mean arterial pressure of70mmHg).One hundred IU/kg of unfractionated heparin were administered intravenouslyin each case. Follow-up was obtained by a review of hospital charts and officerecords, in-person office visits, and telephone and letter interviews with thepatients or their families. It was performed at1,3, and12months within thefirst year after the index procedure and yearly thereafter. Adverse events weremonitored throughout the entire study period. Follow-up three-dimensionalCT scanning was scheduled at one,3and6months after the index procedure unless clinical reasons indicated earlier. End points including all-causemortality, aorta-specific mortality, and progression of aortic pathology definedas the combined end point of crossover (to stent graft)/conversion (to openrepair), additional endovascular or open surgery for rupture, malperfusion oraortic expansion.Results: Patients were followed up until November30,2011(minimum,1month; maximum,104months) and no patient was lost to follow-up.TEVARwas successfully in61patients with no death or intra procedural conversion.In8cases the site of sealing was too close to the left subclavian artery originto spare it and the exclusion of the artery was necessary. The chimney graftwas used in6patients, and no late chimney graft–related endoleak. Thesecases with no neurological sequelae or need for revascularization. Endoleakoccurred in5cases, all are type Ⅰ,3was low volume of the leakage, and2marked endoleak was resolved by a second intervention. The in-hospitalmortality of the TEVAR group was4.8%, while the medical treatment groupwas19.4%(P=0.035). During the follow-up no death (30-days) was observedin the TEVAR group but the thirty-day mortality of the medical treatmentgroup was6.9%(P=0.106). The Kaplan-Meier analysis of survival probabilityat5years was61%with medical treatment and95%with TEVAR respectively,there were significant differences between them (P=0.002log-rank test).Conclusion: TEVAR is a safe and effective procedure to treat thoracicaortic aneurysms with improved perioperative and the mid-term results arebetter than medical treatment. There may be a subset of higher-risk patientswith Stanford type-B dissections who could benefit from TEVAR.