Ann Thorac Surg 2003;75:1781-1784
© 2003 The Society of Thoracic Surgeons
Original article: cardiovascular
Optimal treatment of type B acute aortic dissection: long-term medical follow-up results
Mitsumasa Hata, MD*a,
Motomi Shiono, MDa,
Tatsuya Inoue, MDa,
Akira Sezai, MDa,
Tetsuya Niino, MDa,
Nanao Negishi, MDa,
Yukiyasu Sezai, MDa
a Department of Second Department of Surgery, Nihon University School of Medicine, Tokyo, Japan
Accepted for publication January 6, 2003.
* Address reprint requests to Dr Hata, Second Department of Surgery, Nihon University School of Medicine, 30-1 Ooyaguchi Kamimachi, Itabashi-ku, Tokyo 171-8610, Japan
e-mail: cvshata{at}aol.com
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Abstract
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BACKGROUND: The aim of this study is to assess the long-term outcome of medical treatment and determine recent surgical indications for type B acute aortic dissection.
METHODS: In the last 8 years, 79 patients were admitted to our hospital with type B acute aortic dissection. We medically treated patients at the time of onset, regardless of the aortic diameter and blood patency status in the false lumen. If the maximum diameter of dissected aorta exceeded 60 mm in any stage, early or elective surgery was performed. The mean follow-up duration was 41.2 months. We evaluated operation free rate and actuarial survival rate.
RESULTS: Thirteen patients underwent early or elective operations of the descending aorta. At the time of onset, the maximum aortic diameter of these patients was significantly larger than that of medically managed patients (55.8 ± 4.4 mm vs 44.6 ± 8.2 mm; p = 0.0004). Two patients underwent emergency axillo-femoral bypass for leg ischemia. Of the other 64 patients, who were medically managed, 2 patients had type A dissection develop during follow-up, 3 died during the initial hospital stay (1 from rupture, 1 from bronchial asthma, and 1 from gut ischemia), and 1 died of pneumonia 6 months after onset. Operation free rate was 98.6% at 1 month, 90.0% at 1 year, 78.7% at 3 years, and 69.5% at 8 years. Actuarial survival rate of medically managed patients was 98.4% at 1 month and 93.5% at 8 years.
CONCLUSIONS: Medical treatment of type B acute aortic dissection produced good results. Surgical intervention for type B dissection should be done when the maximum aortic diameter exceeds 60 mm.
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Introduction
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Several investigators have demonstrated that the prognosis of type B acute aortic dissection without fatal complications, such as rupture or vital organ ischemia, was acceptable with medical therapy [1, 2]. However, the long-term results of nonoperative management and indications for surgical intervention for type B aortic dissection in the chronic phase have been variously reported [3–8]. The aim of this study is to assess the long-term acceptability of medical treatment and determine the indications for surgical intervention for type B aortic dissection.
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Patients and methods
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Between June 1994 and June 2002, a total of 79 patients with Stanford type B acute aortic dissection were admitted to our institution. Fifty-one patients (64.6%) were male, and the average age was 64.5 ± 10.1 years (ranged, 33 to 83 years). All patients had a history of hypertension. Three patients (3.8%) had a previous cerebrovascular accident. Four patients (5.1%) had angina pectoris that was medically treated. Six patients (7.6%) had chronic obstructive pulmonary disease. Five patients (6.4%) had Marfan’s syndrome. Forty-seven patients (59.5%) had thrombosed occlusion of the false lumen at the time of onset. In accordance with our treatment protocol (Table 1),
we treated patients nonoperatively at the time of onset, regardless of the diameter of dissected aorta and blood patency status of the false lumen. If the maximum diameter of dissected aorta exceeded 60 mm at the time of onset, surgery was performed within 30 days. All patients received both the tablets of calcium-channel blockers and angiotensin-converting enzyme inhibitors in our outpatient clinic. If the maximum diameter of dissected aorta exceeded 60 mm in the chronic phase, an elective operation was performed. All other patients were medically managed using both drugs (calcium blocker and angiotensin-converting enzyme inhibitor). All patients have been followed-up in our outpatient clinic, and contrast computed tomographic scanning was carried out every 6 months during the follow-up period. Systemic blood pressure was well controlled in all patients, and no patients exhibited refractory hypertension. The mean follow-up duration was 41.2 months (range, 1 to 90 months). The results were expressed as mean ± standard deviation. The difference in the maximum diameter of dissected aorta between the surgical and nonsurgical patients was compared using the Mann–Whitney U test. Statistical significance was defined as a p value of less than 0.05. We evaluated the late mortality and operation free rate with the Kaplan-Meier method. The actuarial survival rate of nonoperative managed patients was also calculated.
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Results
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Two patients (2.6%) underwent emergency axillo-femoral bypass for leg ischemia at the time of onset of type B dissection because they came to the hospital with severe leg pain, cyanosis, paralysis, and pulselessness. Two patients underwent emergency aortic replacement for the complication of type A dissection 6 and 12 months, respectively, after the onset of type B dissection. Elective surgery was carried out in 13 patients (16.5%), including 4 patients with thrombosed occlusion type and 5 patients with Marfan’s syndrome, because the maximum aortic diameter increased to greater than 60 mm (Table 2).
Although all 5 Marfan’s patients also had an enlarged ascending aorta (approximately 50 mm), none were complicated by significant aortic regurgitation.
In the patients undergoing surgical intervention, the maximum diameter of dissected aorta was 55.8 ± 4.4 mm at the time of onset, which had significantly enlarged by the time of operation (68.6 ± 4.1 mm; p = 0.009). The mean duration from the time of onset to surgery was 21.9 ± 13.7 months (range, 1 to 51 months). Four patients had thoracoabdominal aortic replacement, 4 had descending aortic replacement, and 5 had distal arch to the descending aortic replacement. Two patients died of uncontrollable bleeding on the table. One patient died of meningitis 3 months after operation. The operative mortality rate was 15.4%.
The other 64 patients (81.0%) without any surgery for type B dissection or leg ischemia were followed up with medical treatment. Thirty-seven of these patients (59.7%) had thrombosed occlusion of the false lumen, and 16 patients (25.8%) already had an enlarged aorta that was greater than 50 mm at the time of onset. Of those 64 patients, 2 patients underwent emergency ascending aortic replacement for complication of the type A dissection at 6 and 12 months after the onset of type B dissection, respectively. In the other 62 patients, average maximum aortic diameter at the time of onset was 44.6 ± 8.2 mm, which had not changed at the time of this study (44.6 ± 9.2 mm). The maximum diameter of the dissected aorta of the surgically managed patients at the time of onset was significantly larger than that of the medically managed patients (p = 0.0005). One patient died of aortic rupture 3 days after onset, with an aortic diameter of 65 mm at the time of onset. Two patients died of gut ischemia and bronchial asthma within 30 days after the onset. One patient died of respiratory failure 6 months after the onset. The operative free survival rate for 75 patients (excluding 4 patients who died) was 98.6% ± 1.3%, 90.0% ± 3.6%, 78.7% ± 5.0%, and 69.5% ± 6.7% at 1 month, 1 year, 3 years, and 8 years, respectively (Fig 1).
The actuarial survival rate for the 62 medically managed patients was 98.4% ± 1.6% and 93.5% ± 3.1% at 1 month and 8 years, respectively (Fig 2).
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Fig 1. The operative free survival rate for 75 patients excluding 4 patients who died was 98.6% ± 1.3%, 90.0% ± 3.6%, 78.7% ± 5.0%, and 69.5% ± 6.7% at 1 month, 1 year, 3 years, and 8 years, respectively.
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Fig 2. The actuarial survival rate for the 62 medically managed patients was 98.4% ± 1.6% and 93.5% ± 3.1% at 1 month and 8 years, respectively.
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Comment
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It should be kept in mind that many patients with type B dissection had large aneurysms requiring extensive operations [4]. However, the mortality rate of patients undergoing surgical intervention for type B dissection is still very high [5]. Although endovascular stent therapy was developed to treat the acute type B dissection, the clinical criteria of patient selection is still unclear [9]. In particular, in Japan the Ministry of Health and Welfare has not yet approved the thoracic endovascular stent device. Therefore, it has been generally advocated that patients with type B acute aortic dissection without complications (such as rupture or vital organ ischemia) should be treated with hypotensive drugs at the time of onset, and surgical treatment should be carried out only if the aortic diameter becomes enlarged during the follow-up period [6].
When should we employ the surgery for type B dissection? Kato and colleagues [7] suggested that surgery was indicated for type B dissection during the acute phase in patients whose aortic diameter exceeds 40 mm. They demonstrated that a diameter of dissected aorta of 40 mm or more predicted aortic enlargement in the chronic phase, particularly if the false lumen was patent. On the other hand, Bernard and colleagues [10] mentioned that 48% of patients who survived the in-hospital period had a false lumen that had a tendency toward an occlusion at 5 years. Several investigators demonstrated that there was no difference in the annual growth rate between aneurysm with patent false lumen and aneurysm with thrombosed false lumen [4, 5]. In the present study, we medically treated patients at the time of onset, regardless of the diameter of dissected aorta and the blood patency status of false lumen. If the maximum diameter of dissected aorta exceeded 60 mm, surgical intervention was performed. The aortic diameter of less than 50 mm at the time of onset did not tend to enlarge during follow-up period. Iguchi and Tabayashi [5] also described that medical treatment was indicated for all patients with the uncomplicated type B dissection if the diameter of dissected aorta was less than 50 mm and substantial enlargement of dissected aorta was not observed during a short interval. Gysi and colleagues [8] reported that the 30-day mortality rate of type B dissection was lower and death usually occurred later, caused by aortic rupture, extension of dissection, or aneurysms in the descending aorta. Juvonen and colleagues [4] reported that after patients had survived an acute episode of dissection without surgical intervention, an operation for a new chronic type B dissection was usually recommended if the aneurysm exceeded 50 mm in maximum diameter or appeared to be expanding rapidly. These authors reported that the average rate of expansion of the patients undergoing surgery was 4.2 mm (range, 0 to 48 mm/yr). In our present study the average rate of expansion was 7.2 mm (range, 2.7 to 17 mm/yr), excluding 1 patient undergoing surgery 1 month after onset. Juvonen and colleagues [4] also described that rapid expansion may lead to rupture in chronic type B dissections, and the last median descending aortic diameter before rupture was 54 mm.
However, in the present study we treated the patient with medical therapy, even if the maximum aortic diameter exceeded 50 mm at the time of onset. An operative free survival rate at 8 years was approximately 70%. In particular, of our 62 patients who were treated with medical therapy, 16 patients (25%) already had an enlarged aorta exceeding 50 mm at the time of onset. In the patient whose aorta ruptured early, the aortic diameter was 65 mm at the time of onset. The maximum diameter of dissected aorta of the other 15 patients did not change at the time of this study. On the other hand, the aortic diameter of the 13 patients who underwent elective surgery had exceeded 50 mm at the time of onset, and this diameter increased to more than 60 mm at the time of surgery. Five of these patients (38.5%) had Marfan’s syndrome, and examination of the other 8 patients revealed slightly, rapidly increasing aortic diameter during a 2- to 3-year period. In these 13 patients, systemic blood pressure was well controlled, and of course, we took care of these patients quite closely. Therefore, even when the aortic diameter exceeded 60 mm, we did not observe rupture during the follow-up period. Elefteriades and colleagues [3] also reported that current size criterion of the surgery for asymptomatic patients is 65 mm. As previously mentioned, there were 24 patients excluding those who had Marfan’s syndrome, whose dissected aorta exceeded 50 mm at the time of onset in the present study. In 15 of these patients (62.5%), the diameter of dissected aorta did not change during the follow-up period. Therefore, even though the dissected aorta already exceeded 50 mm at the time of onset, medical treatment was effective to prevent further aortic dilatation for more than 50% of the patients. Even if the aortic diameter had increased to more than 60 mm, careful follow-up of the patients was made to prevent aortic rupture. Most of the patients have remained very well in our outpatient clinic.
Genoni and colleagues [11] reported that freedom from subsequent aortic operation was 80% with ß-blockers and 47% with another hypotensive drug. We hesitate to use ß-blockers because some patients had complications with bronchial asthma, heart failure, or respiratory failure during the intensive care unit (ICU) stay. In patients with type B dissection we believe it is important to reduce the mental and physical stress of the patient. Therefore care must be taken to prevent complications related to prolonged bed rest. We usually transfer patients with type B dissection from the ICU to the surgical ward 2 days after onset at which time walking is recommended. We usually discharge these patients after 3 weeks of hospital observation. The long-term survival rate of medically managed patients was 93.5%. This rate demonstrates that medical therapy is quite acceptable; however, we believe it is important to closely follow-up the patient by ourselves in our outpatient clinic.
In conclusion, medical treatment for type B acute aortic dissection showed good results. The most reasonable option for management for patients with acute type B dissection appeared to be a continued strategy of aggressive medical therapy and close observation, unless the patients had uncontrollable back pain or fatal complications such as a rupture or vital organ ischemia. The surgical indication for type B dissection is the detection of a maximum aortic diameter that exceeds 60 mm.
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References
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- Glower D.D., Fann J.I., Speier R.H., et al. Comparison of medical and surgical therapy for uncomplicated descending aortic dissection. Circulation 1990;82(Suppl IV):39-46.
- Wheat M.W. Acute dissecting aneurysms of the aorta: diagnosis and treatment—1979. Am Heart J 1980;99:373-387.[Medline]
- Elefteriades J.A., Lovoulos C.J., Coady M.A., Tellides G., Kopf G.S., Rizzo J.A. Management of descending aortic dissection. Ann Thorac Surg 1999;67:2001-2005.
- Juvonen T., Ergin M.A., Galla J.D., et al. Risk factors for rupture of chronic type B dissections. J Thorac Cardiovasc Surg 1999;117:776-786.[Abstract/Free Full Text]
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- Gysi J., Schaffner T., Mohacsi P., Aeschbacher B., Althaus U., Carrel T. Early and late outcome of operated and non-operated acute dissection of the descending aorta. Eur J Cardio Thorac Surg 1997;11:1163-1170.[Abstract]
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- Genoni M., Paul M., Jenni R., Graves K., Seifert B., Turina M. Chronic ß-blocker therapy improves outcome and reduces treatment costs in chronic type B aortic dissection. Eur J Cardio Thorac Surg 2001;19:606-610.[Abstract/Free Full Text]
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Abstract
Introduction
