Correspondence
Small Abdominal Aortic Aneurysms
N Engl J Med 2002; 347:1112-1115October 3, 2002
- Article
To the Editor:
Two randomized trials reported by Lederle et al.1 and the United Kingdom Small Aneurysm Trial Participants2 (May 9 issue) revealed that early surgery in patients with small abdominal aortic aneurysms can only be expected to have a benefit if the risk of surgery is considerably smaller than the risk of spontaneous rupture. Operative mortality rates in these studies ranged from 2.7 to 5.5 percent, and the annual risk of a spontaneous rupture was 0.6 percent in one study and ranged from 1.6 to 3.2 percent in the other.
The decision about whether to perform early surgery or to institute surveillance should be made on an individual basis, after an evaluation of the perioperative risk. In a group of 661 patients (mean age, 67 years; 532 of them men) who underwent elective abdominal aortic surgery in our institution between 1991 and 2000, the perioperative mortality was 9.1 percent (mortality from cardiac causes, 4.1 percent). Patients without chronic pulmonary disease or cardiac risk factors — including angina, myocardial infarction, diabetes mellitus, heart failure, stroke, and renal failure — represent a population at low risk for operative death. Patients with one or more cardiac risk factors were further stratified according to the absence or presence and extent of myocardial ischemia, as determined by dobutamine echocardiography (Figure 1Figure 1
Estimate of the Perioperative Risk of Death from Noncardiac and Cardiac Causes.). Patients without stress-induced ischemia had a low-to-intermediate perioperative risk, despite the presence of clinical risk factors.In view of these data, we suggest that risk assessment and modification be undertaken for each patient. This process includes the identification of risk factors, an objective evaluation of myocardial ischemia, and the administration of proper perioperative medical therapy (beta-blockers) or coronary revascularization.
2 ReferencesMiklos D. Kertai, M.D.
Eric Boersma, Ph.D.
Don Poldermans, M.D.
Erasmus Medical Center, 3015GD Rotterdam, the Netherlands
poldermans@hlkd.azr. nl 1
Lederle FA ,Wilson SE ,Johnson GR , et al. Immediate repair compared with surveillance of small abdominal aortic aneurysms. N Engl J Med 2002;346:1437-1444
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The United Kingdom Small Aneurysm Trial Participants
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To the Editor:
The articles by Lederle et al. and the United Kingdom Small Aneurysm Trial Participants both suggest that aneurysms can be followed carefully until their diameter reaches 5.5 cm. If perioperative mortality is high, and if patients are more likely to die from other causes than from the aneurysm in the several subsequent years, then the conservative strategy will look even better. The older a patient is, the more likely it is that these two conditions will be met. The mean age in both trials was less than 70 years. Can the authors make any more specific recommendations about how older age should affect the decision to repair electively abdominal aortic aneurysms that are discovered incidentally?
Thomas E. Finucane, M.D.
Johns Hopkins University, Baltimore, MD 21224
tfinuc@jhmi.edu To the Editor:
In their controlled, randomized study, Lederle et al. found that long-term mortality did not differ between the surveillance group and the immediate-surgery group. The authors conclude that these data “support a policy of reserving elective repair for abdominal aortic aneurysms at least 5.5 cm in diameter.” Given the fact that an accumulated 70 percent of the surveillance group underwent repair by the end of the study — and more strikingly, that half of this population required surgery by three and a half years — we find this conclusion remarkable.
If the majority of patients will need surgery anyway, why follow them until they do? Why subject patients to the anxiety, expense, and inconvenience of being scanned for a period of years instead of just fixing the problem and being done with it? As long as operative mortality is under 2 percent, surveillance provides no advantage beyond repeated confirmation of the natural history.
Caution must be exercised in applying the results of clinical trials to clinical practice. Women, who are known to have a higher rate of rupture for aneurysms of a given size,1 made up less than 1 percent of the study population. In cases in which computed tomographic scanning is indicated, the expense of watchful waiting in terms both of dollars and exposure to radiation is high. Mortality among patients who do not comply with surveillance was not studied, and such noncompliance could be disastrous.
This study shows that surveillance is equivalent to immediate surgery with respect to long-term mortality under highly controlled conditions. Whether it is effective clinical practice is another matter entirely.
1 ReferencesCharles C. Miller, III, Ph.D.
Tam T. Huynh, M.D.
Hazim J. Safi, M.D.
University of Texas Medical School, Houston, TX 77030
charles.c. miller@uth. tmc. edu 1
Brown LC ,Powell JT . Risk factors for aneurysm rupture in patients kept under ultrasound surveillance. Ann Surg 1999;230:289-296
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To the Editor:
The results of the study by Lederle et al. confirming the conclusions of the United Kingdom Small Aneurysm Trial will undoubtedly have a striking influence on the management of small abdominal aortic aneurysms. However, we wonder about the advisability of generalizing the final recommendation — that small abdominal aortic aneurysms should be observed until they reach at least 5.5 cm in diameter and that repair should be avoided unless they expand rapidly or symptoms develop.
The safety of ultrasonographic surveillance is dependent on meticulous follow-up that is unlikely to be achievable in routine practice outside a controlled trial. It is no surprise that Valentine et al.1 report, in a program based on watchful waiting involving 101 veterans with small abdominal aortic aneurysms, that 32 percent did not comply with the follow-up, missing at least three consecutive appointments and accounting for a rate of aneurysm rupture of 13 percent in 34 months. The selected patients enrolled in the study by Lederle et al. were not high-risk patients and were therefore presumably most likely to benefit from elective repair. In practice, many good candidates for repair become poor candidates during the period of watchful waiting, as congestive heart failure develops, chronic obstructive pulmonary disease worsens, or other problems occur.1-3
Moreover, the fact that 61.6 percent of patients in the surveillance group underwent repair within 4.9 years confirms that the issue of aneurysm repair for such patients with a good life expectancy is a matter of when rather than if. Given the relatively low risk of rupture for small abdominal aortic aneurysms, for early repair to be recommended, the perioperative outcome has to be outstanding and consistent with the situation reported in the trial.
3 ReferencesEnzo Ballotta, M.D.
Antonio Toniato, M.D.
Università degli Studi di Padova, 35128 Padua, Italy
enzo.ballotta@unipd. it 1
Valentine RJ ,Decaprio JD ,Castillo JM ,Modrall JG ,Jackson MR ,Clagett GP . Watchful waiting in cases of small abdominal aortic aneurysms -- appropriate for all patients? J Vasc Surg 2000;32:441-450
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Katz DA ,Littenberg B ,Cronenwett JL . Management of small abdominal aortic aneurysms: early surgery vs watchful waiting. JAMA 1992;268:2678-2686
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Nicholls SC ,Gardner JB ,Meissner MH ,Johansen HK . Rupture in small abdominal aortic aneurysms. J Vasc Surg 1998;28:884-888
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Author/Editor Response
The authors reply:
To the Editor: Because more than half of our surveillance group underwent aneurysm repair, Miller et al. and Ballotta and Toniato question our conclusion that elective repair should be reserved for abdominal aortic aneurysms of 5.5 cm or larger. Any operative threshold based on the diameter of the aneurysm (such as 5.5 cm) will eventually be crossed in many patients whose aneurysms are smaller at the outset. Lowering the threshold would result in the same scenario, in which abdominal aortic aneurysms in many patients eventually reach the new threshold; this logic would lead to repeated lowering of the threshold and ultimately to the repair of all abdominal aortic aneurysms. If all small abdominal aortic aneurysms (which are common and have a low risk of rupture) were repaired, the number of operative deaths as a result would probably greatly exceed the number of rupture-related deaths prevented. The 5.5-cm threshold has been shown in two randomized trials to result in a safe reduction of the number of operations performed (by an estimated 20 percent in our study), and we see no advantage to changing it. Surveillance with ultrasonography is adequate and inexpensive and does not require exposure to radiation. The assertion by Ballotta and Toniato that operative mortality will increase when surgery is deferred is not supported by our findings.
The most important consideration in applying our results to clinical practice is that higher operative mortality in other settings or groups of patients may be an indication for raising the threshold for elective repair beyond 5.5 cm, as implied by the letters from Finucane and Kertai et al. Our trial data do not support precise recommendations for patients who differ from the trial patients, although we have reported rupture rates among patients with large abdominal aortic aneurysms and high operative risk elsewhere.1 Women are not well represented in our study, but there is more evidence for increased operative mortality among women2-4 than there is for a higher rate of rupture,5 making it difficult to justify a lower threshold in women.
As noted by Miller et al. and Ballotta and Toniato, compliance with follow-up imaging is extremely important, but the optimal management of aneurysms in noncompliant patients remains unclear. The conclusions of the study by Valentine et al. (cited by Ballotta and Toniato) are based on only three episodes of rupture, and the operative mortality for elective repair in that study was 8 percent — which again makes it difficult to justify a lower threshold for repair. Physicians who wish to individualize patient care should be aware that there is no group of patients for whom elective repair of abdominal aortic aneurysms that are less than 5.5 cm has been shown to be beneficial.
Recently obtained medical records have allowed our outcomes committee to reclassify one death of a patient in the surveillance group in our study as a rupture-related death (so that the risk of such death is now 0.7 percent per year), and five deaths (two in the immediate-repair group and three in the surveillance group) have been classified as indirectly due to aneurysm repair (including the one following the repair of a ventral hernia that was mentioned in the article). There have thus been 19 deaths related to abdominal aortic aneurysm in each group (relative risk in the surveillance group, 1.03; 95 percent confidence interval, 0.54 to 1.94).
5 ReferencesFrank A. Lederle, M.D.
Veterans Affairs Medical Center, Minneapolis, MN 55417
frank.lederle@med. va. gov for the Aneurysm Detection and Management Veterans Affairs Cooperative Study Group
1
Lederle FA ,Johnson GR ,Wilson SE , et al. Rupture rate of large abdominal aortic aneurysms in patients refusing or unfit for elective repair. JAMA 2002;287:2968-2972
CrossRef | Web of Science | Medline2
Katz DJ ,Stanley JC ,Zelenock GB . Gender differences in abdominal aortic aneurysm prevalence, treatment, and outcome. J Vasc Surg 1997;25:561-568
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Wen SW ,Simunovic M ,Williams JI ,Johnston KW ,Naylor CD . Hospital volume, calendar age, and short term outcomes in patients undergoing repair of abdominal aortic aneurysms: the Ontario experience, 1988-92. J Epidemiol Community Health 1996;50:207-213
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Manheim LM ,Sohn MW ,Feinglass J ,Ujiki M ,Parker MA ,Pearce WH . Hospital vascular surgery volume and procedure mortality rates in California, 1982-1994. J Vasc Surg 1998;28:45-58
CrossRef | Web of Science | Medline5
Brown LC ,Powell JT . Risk factors for aneurysm rupture in patients kept under ultrasound surveillance. Ann Surg 1999;230:289-296
CrossRef | Web of Science | Medline
To the Editor:
The increasing importance of patients' involvement in decision making makes high-quality evidence and honesty essential. First, as Kertai and colleagues note, in the “real world,” operative mortality rates for elective aneurysm repair are likely to be as high as 8 to 9 percent — 1 in 12 patients will die as the result of prophylactic elective surgery.1 Second, the safety of surveillance for small aneurysms has been demonstrated in the two trials recently reported in the Journal and in the care of patients with aneurysms detected through screening studies.2 The study mentioned by Ballotta and Toniato was very small. Third, there is currently no prospectively validated method of risk assessment for patients undergoing open aneurysm repair, although the revised Goldman Cardiac Risk Index holds promise.3 In the United Kingdom Small Aneurysm Trial, with its pragmatic approach to preoperative assessment, physiological age appeared to be more important than chronologic age: poor renal and lung function were the most important predictors of postoperative mortality.4 Fourth, neither the study by Lederle et al. nor ours identified a subgroup of patients, defined according to age or aneurysm diameter, who benefited from early surgery.
Given the rapid advances in endovascular repair and pharmacology, why not wait safely, with the potential for a less invasive method of management later, rather than take a 1-in-12 chance of death now? Cost-conscious health economies are also likely to support this approach.5 The focus should now be on advancing endovascular technology, so that a higher proportion of patients with aneurysms of 5.5 cm or more in diameter can undergo endovascular correction with low operative mortality and assured durability.
5 ReferencesJanet Powell, Ph.D., M.D.
Tony Brady, M.Sc.
Roger Greenhalgh, M.D.
University Hospitals of Coventry and Warwickshire, Coventry CV2 2DX, United Kingdom
janet.powell@wh-tr. wmids. nhs. uk for the United Kingdom Small Aneurysm Trial Participants
1
Thompson RW . Detection and management of small aortic aneurysms. N Engl J Med 2002;346:1484-1486
Full Text | Web of Science | Medline2
Scott RAP ,Wilson NM ,Ashton HA ,Kay DN . Influence of screening on the incidence of ruptured abdominal aortic aneurysm: 5-year results of a randomized controlled study. Br J Surg 1995;82:1066-1070
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Karkos CD ,Thomson GJ ,Hughes R ,Hollis S ,Hill JC ,Mukhopadhyay US . Prediction of cardiac risk before abdominal aortic reconstruction: comparison of a revised Goldman Cardiac Risk Index and radioisotope ejection fraction. J Vasc Surg 2002;35:943-949
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Brady AR ,Fowkes FG ,Greenhalgh RM ,Powell JT ,Ruckley CV ,Thomson SG . Risk factors for postoperative death following elective surgical repair of abdominal aortic aneurysm: results from the UK Small Aneurysm Trial. Br J Surg 2000;87:742-749
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UK Small Aneurysm Trial Participants
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- Citing Articles (3)
Citing Articles
1
Shinji Takai, Denan Jin, Mizuo Miyazaki. (2011) Targets of chymase inhibitors. Expert Opinion on Therapeutic Targets1-9
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Nao Inoue, Michiko Muramatsu, Denan Jin, Shinji Takai, Tetsuya Hayashi, Hiroshi Katayama, Yasushi Kitaura, Hiroshi Tamai, Mizuo Miyazaki. (2009) Effects of chymase inhibitor on angiotensin II-induced abdominal aortic aneurysm development in apolipoprotein E-deficient mice. Atherosclerosis 204:2, 359-364
CrossRef3
Nao Inoue, Michiko Muramatsu, Denan Jin, Shinji Takai, Tetsuya Hayashi, Hiroshi Katayama, Yasushi Kitaura, Hiroshi Tamai, Mizuo Miyazaki. (2009) Involvement of Vascular Angiotensin II-Forming Enzymes in the Progression of Aortic Abdominal Aneurysms in Angiotensin II- Infused ApoE-Deficient Mice. Journal of Atherosclerosis and Thrombosis 16:3, 164-171
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