Is close radiographic and clinical control after repair of acute type A aortic dissection really necessary for improved long-term survival?

Abstract

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether radiographic and clinical control after surgery for acute type A aortic dissection (AAD) is needed for improved long-term survival. Altogether, 118 relevant papers were identified using the reported search, of which seven represented the best evidence to answer the question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We conclude that most patients after surgery for AAD remain at risk for dissection-related aortic complications. Late aortic growth is often slow and linear, but the occurrence of major aortic events is unpredictable and can initially present more than a decade postoperatively. Risk factors for rapid late aortic enlargement and reoperations include patent or partially thrombosed false lumen, large aortic size, Marfan syndrome and younger age. Whether performing a more extensive first procedure (e.g. aortic arch replacement±elephant trunk) can be translated into improved outcome and a lower incidence of aorta-related reoperations remains to be elucidated. Aortic reoperation rates range between 10% and >20% within the first 10 years. Optimal systolic blood pressure control (<120 mmHg), including β-blocker therapy, seems to decrease late aortic dilatation and the incidence of aortic reoperations. Close and careful lifelong surveillance of patients after AAD repair including radiographic and clinical controls to evaluate the status of the remaining aorta, and thus to facilitate adaptations of medical therapy and planning of timely reprocedures seems mandatory for improved long-term survival. A suggested timeframe for computed tomographic (CT) imaging after surgery for AAD is before discharge, at six and 12 months postdissection and, if stable, annually thereafter. Patients with large aneurysms (aortic diameter ≥50 mm) should be maintained at radiographic intervals of six months or less. If the thoracic aneurysm is moderate in size and remains stable over time, magnetic resonance imaging instead of CT-scanning is reasonable to minimize the patient's radiation exposure.

1. Introduction

A best evidence topic was constructed according to a structured protocol, which has been fully described [1].

2. Three-part question

In [patients after surgery for acute type A aortic dissection] is [close radiographic and clinical control] necessary compared to [symptom-only based investigations] for improved [long-term survival]?

3. Clinical scenario

A 64-year-old man undergoes emergency surgery for acute type A aortic dissection (AAD). The postoperative course is uneventful. A computed tomographic (CT) scan before discharge shows an unremarkable aortic prosthesis and a patent residual false lumen in the aortic arch and descending aorta. The maximum diameter of the thoracic aorta is 45 mm. You ask yourself how often this patient should undergo radiographic and clinical control to identify early dissection-related aortic complications and to achieve improved long-term survival?

4. Search strategy

Medline 2000–2010 was searched using Pubmed to obtain the relevant papers, with the terms [surgery] AND [acute type A aortic dissection] AND [long-term survival].

5. Search outcome

A total of 118 relevant papers were found, from which seven were selected as representing the best evidence to answer the clinical question (Table 1 ).

6. Results

We reviewed seven studies including clinical and radiographic (mainly CT-scanning) long-term data of 1250 patients after surgery for AAD.

Geirsson et al. [2] analyzed 221 patients after surgery for AAD. Freedom from proximal reoperations was 95.1% and 77.8% at five and 10 years, respectively. Aortic valve resuspension techniques were durable and survival was similar to that after aortic root replacement. Freedom from distal reoperation was 86.5% and 75.4% at five and 10 years, respectively. Patients <45 years, and those with DeBakey type 1 dissection had a higher risk of distal reoperation. In-hospital mortality of reoperation was 18.2% in proximal reoperations, and 31.2% in distal reoperations. Long-term survival was 79.2%, 62.8%, and 46.3% at one, five and 10 years, respectively.

Halstead et al. [3] revealed postsurgery aortic growth rates of 0.8 mm/year (aortic arch) and 1 mm/year (descending aorta). Risk factors for rapid enlargement of the distal aorta were male gender, initial aortic size >40 mm and patency of the false lumen. There was a 17% reoperation rate in 17 years follow-up. One (4%) perioperative death occurred among those reoperations. The sum of deaths caused by aortic rupture, graft infection, and unknown causes represented 40% of late deaths corresponding to a two-fold increase in long-term deaths compared with healthy controls.

Immer et al. [4] found that younger age, female gender, dissection of the supraaortic branches, preoperative malperfusion or persistent patent false lumen were all risk factors for late aortic dilatation. Over a period of 60 months, aortic growth of up to 20 mm was seen in 42.2%, and of more than 20 mm in 17.2%, among whom more than 80% required aortic reoperation. Secondary aortic dilatation occurred in the majority of patients within the first 24 months.

Kimura et al. [5] showed that the aortic growth rate is higher in patients with a residual patent false lumen compared with those with a thrombosed lumen. Freedom from distal aortic reoperation for all hospital survivors was 99%, 97.4% and 89.5% at one, five and 10 years, respectively. Patients within the thrombosed group showed a tendency to fewer distal reoperations compared with the patent group. Actuarial survival with in-hospital deaths was 89.5%, 79.5% and 71.3% at one, five and 10 years, respectively, and was similar in patients with a patent lumen and those with a thrombosed false lumen.

Zierer et al. [6] revealed that Marfan syndrome, non-resected primary tear, absence of postoperative β-blocker therapy, and systolic blood pressure (SBP) of more than 140 mmHg at late follow-up were predictors of late re-operation. Risk factors for aortic growth were aortic diameter, elevated SBP and patent false lumen. Moderate aneurysms (35–49 mm) rarely showed growth at <6-month intervals, whereas aneurysms ≥50 mm demonstrated growth in <6 months. Most important, the timing of the onset of aortic enlargement was unpredictable. Optimal blood pressure control (SBP <120 mmHg) decreased the incidence of secondary aortic dilatation from 34 to 14%, and decreased the incidence of late reoperation from 35 to 8%. Freedom from reoperation at 10 and 15 years was 79% and 75%, respectively, with β-blocker therapy, and 57% and 25%, respectively, without β-blocker therapy.

Fattouch et al. [7] found a reoperation rate of 22.7% in a mean follow-up of 88±44 months. Predictors for aortic reoperation were aortic size >45 mm, patent false lumen and Marfan syndrome. Actuarial survival rates for the entire population were 97.7%, 88.2% and 79.8% at one, five and 10 years, respectively.

Song et al. [8] showed freedom from distal reoperations rates of 94.6%, 78.8% and 66.1% at one, five and 10 years, respectively. They revealed that partial thrombosis compared with completely patent or thrombosed false lumen is a strong predictor of rapid aortic growth, poor long-term survival and aorta-related reoperations. Patients with total arch replacement showed a lower incidence of partial thrombosis in the distal aorta and no aorta-related reoperations. However, the operative mortality of the initial surgery was relatively high with 17.8%. Whether such an aggressive initial approach can be translated into improved outcome remains to be elucidated.

7. Clinical bottom line

Patients after repair of AAD often show persistent dissection of the remaining aorta and subsequently, are at risk for aortic complications. Late aortic growth is often slow and linear, but the occurrence of major aortic events is unpredictable. Aortic reoperation rates range between 10% and more than 20% within the first 10 years. Optimal SBP control (SBP <120 mmHg), including β-blocker therapy, seems to decrease late aortic dilatation and the incidence of aortic reoperations. Whether ATII receptor blockers and ACE inhibitors may lead to additional benefits (e.g. stabilization of the aortic wall) requires further studies [9]. Close and careful surveillance of patients after AAD repair including radiographic and clinical controls to evaluate the status of the remaining aorta, in order to adapt medical therapy and to plan timely reprocedures seems mandatory for improved long-term survival.

References