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Ann Thorac Surg 1995;59:1204-1209
© 1995 The Society of Thoracic Surgeons

Unoperated Aortic Aneurysm: A Survey of 170 Patients

Departments of Cardiothoracic Surgery, Cardiology and Vascular Surgery, Rigshospitalet, The National University Hospital, Copenhagen, Denmark

Accepted for publication February 7, 1995.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
From 1984 to 1993, 1,053 patients were admitted with aortic aneurysm (AA) and 170 (15%) were not operated on. The most frequent reason for nonoperative management was presumed technical inoperability. Survivals for patients with thoracic, thoracoabdominal, and abdominal AA were comparable. No significant differences in survival for patients with dissecting and nondissecting AA were detected. In all, 132 patients (78%) died and 78 (59%) of them died of rupture. Mean time to rupture was 1,300 ± 8 days. Cumulative 5-year hazard of rupture for the dissecting AA was twice that of the nondissecting (p < 0.001). Hazards of rupture for type A and B dissections were comparable. Diameter of 6 cm or greater was associated with a fivefold increase in cumulative hazard of rupture (p < 0.001). Diameter of AA, incidence of renal failure, and arterial hypertension were predictive of mortality, whereas the first two variables were predictive of rupture. In conclusion, because the majority of patients in all subgroups died of rupture, all patients should be recognized as candidates for surgical treatment. Present data justify aggressive approach to the patient with AA 6 cm or more in diameter and type A dissections. The results suggest that type B dissections may have a more favorable course if operated on, but a prospective, randomized study is necessary to confirm this observation. We believe that older patients and those with a small aneurysm may benefit from early, elective operation.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Decreasing mortality after surgical treatment of thoracic (TAA) [1], thoracoabdominal (T-AAA) [2, 3] and abdominal aortic aneurysm (AAA) [4] inspired this retrospective study about the natural history of unoperated patients. The question is whether improvement in medical care and surveillance influence mortality of the nonoperated patients and whether there are any differences in survival with respect to location of the aneurysm. Considering different etiology of the disease [5] and attitude toward operation, variation in reasons for conservative treatment, early mortality, and late survival can be expected.

This study was undertaken to determine risk factors, causes of death, and survival among nonoperated patients with aortic aneurysm (AA). We analyzed hazard and risk factors for rupture to identify low-risk patients, who eventually might profit from conservative treatment.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
During 1984 to 1993 1,053 patients were admitted with AA and 170 (15%) were not operated on. Fifty-seven patients (34%) had TAA, 53 (31%) had T-AAA, and 60 (35%) had AAA. The mean age of 69 years (range, 32 to 93 years) was similar for the 115 men and 55 women and had the following distribution between groups: 64, 68, and 73 years for TAA, T-AAA, and AAA, respectively (p < 0.05). Corresponding male/female ratios were 1.1, 2.5, and 3.6 (p < 0.01).

An aneurysm was defined as a localized dilatation of the aorta exceeding 150% of the diameter above or below the dilatation or aortic diameter exceeding 150% of normal size related to the age of the patient [6]. Acute traumatic AA was not included in the study. The diagnosis of the AA were established or confirmed by ultrasonography, computed tomographic scan, angiography, or autopsy in all patients. In 17 patients precise diameter of AA was not established before rupture or death. Mean diameter at the recognition of aneurysms was 6.3 cm (range, 4 to 10 cm) and did not differ between the groups. Thirty-six aneurysms (21%) were less than 5 cm in diameter (``small AA'') with the following distribution: 12 TAA, 6 T-AAA, and 18 AAA. An AA that originated and ended above the celiac trunk was considered as TAA, an AA that involved the visceral arteries was termed T-AAA, and AAAs originated beneath the celiac trunk.

Aortic dissection was present in 38 patients (22%): 27 TAA (47%) and 11 T-AAA (21%); none of the AAAs dissected. Stanford type A dissection (involving the ascending aorta) was observed in 18 patients, whereas 20 had Stanford type B dissection originating from the arch in 8 and distal to the left subclavian artery in 12 patients.

Hypertension was recognized in 85 (50%) patients; congestive heart failure (New York Heart Association class II through IV) occurred in 59 (35%); renal failure with urea and creatinine level elevation in 41 (24%); and respiratory insufficiency (forced expiratory volume in 1 second <1.0 L) in 41 patients (24%). Distribution of associated diseases was similar in the three AA groups. At the time of diagnosis 64 patients were free of symptoms, whereas 106 (62%) had symptoms with possible relation to the aneurysm such as chest, abdominal, or back pain. Acute renal dysfunction (anuria or oliguria) was present in 19 patients (11%). None of the patients underwent operation for AA during follow-up.

Mortality data were obtained in all cases from charts, autopsy reports, death certificates, and the Danish Health Care Registry. Survival was analyzed using the Kaplan-Meier method. Hazard of rupture was calculated and the probability was determined from the relationship between the cumulative hazard function and the cumulative distribution [7]. Log-rank test was used to detect differences in survival or hazard between samples. Cox proportional hazard regression was used to identify risk factors predictive of mortality and rupture. Eleven factors were tested: age, sex, associated diseases (as above), anuria at admittance, symptoms related to AA, location of AA, transverse diameter of AA, and dissection. When multiple comparisons were employed, the p level less than 0.01 was considered significant, otherwise, p less than 0.05 was accepted. Descriptive statistics are given as mean with range or percentage in parentheses; results of statistical tests are given as mean ± standard error of the mean.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Table 1 lists the dominant reasons for nonoperative management. Presumed technical inoperability was the most frequent reason, particularly among T-AAAs. Nearly half of the AAA patients were not operated on due to severe associated diseases, whereas small size and advanced age (>70 years) were the dominating reasons among patients with TAA. In many cases, however, multiple factors precluded operation.

View larger version (27K): [in this window] [in a new window]   Fig 1. . Survival curve (Kaplan-Meier) according to aneurysm location. The table lists the number of patients remaining in the study at the relevant point in time. (AAA = abdominal aortic aneurysm; TAA = thoracic aortic aneurysm; T-AAA = thoracoabdominal aortic aneurysm.)

View larger version (25K): [in this window] [in a new window]   Fig 2. . Survival curve (Kaplan-Meier) of patients with dissecting and nondissecting aneurysms. The table lists the number of patients remaining in the study at the relevant point in time.

View larger version (19K): [in this window] [in a new window]   Fig 3. . Survival curve (Kaplan-Meier) of patients with Stanford type A and type B dissection. The table lists the number of patients remaining in the study at the relevant point in time.

View larger version (70K): [in this window] [in a new window]   Fig 4. . Hazard and probability plot: Mean time to rupture is found on the vertical time scale corresponding to 50% point on the horizontal probability scale.

View larger version (69K): [in this window] [in a new window]   Fig 5. . Hazard and probability plot of patients with dissecting and nondissecting aneurysms.

View larger version (70K): [in this window] [in a new window]   Fig 6. . Hazard and probability plot of patients with aneurysms less than 6 cm and 6 cm or more in diameter.

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

Age
In the present study, half of the patients who were not operated on principally due to advanced age died of rupture within 1.5 year. Age has been identified as a risk factor predictive of perioperative and postoperative mortality after T-AAA [3] and AAA [10] repair. However, perioperative (within 30 days) mortality for patients older than 70 years was reported as less than 10% for elective, 23% for acute but nonruptured, and 46% for ruptured AAA. Moreover, after exclusion of the perioperative period, postoperative survival rate for those patients was similar to an age- and sex-matched background population [10]. Thus, older patients presenting with nonruptured AA have about a 50% risk of death due to rupture within 1.5 year if not operated on and a 77% to 90% chance to survive 5 years until death from other causes if operated on.

Diameter
In our material, increasing diameter of the AA was predictive of mortality and rupture in all three AA location groups. Hazard analysis indicated that 66% of the AAs 6 cm or more in diameter will rupture within 5 years if not operated on. However, small aneurysms also may rupture [11], and in the present study 14% of the patients with small AA (<5 cm) died of rupture. On the other hand, large AAs may remain unruptured for years as we found two AAs of more than 6 cm unruptured for at least 5 years. Although T-AAA operation carries a high risk of paraplegia and renal failure, neither the size nor extent of the aneurysm were found to influence perioperative mortality after elective T-AAA or AAA repair [3, 12]. Inclusion of the aortic arch in repair of a TAA is a significant risk factor for perioperative death, although in expert hands mortality may be no more than about 10% [13]. Thus, in our experience, patients with a small aneurysm should be offered elective AA repair without unnecessary delay. Patients with extensive TAA or T-AAA should be referred for operation if there are no other factors limiting survival.

High-Risk Patients
Presently, neither anuria nor patients' subjective symptoms were found to be predictive of survival or rupture in multivariate analysis. Moreover, congestive heart failure did not influence survival. It may be puzzling that hypertension was not predictive of rupture as in the postoperative survival reported by Rizzoli and associates [14], but these results may indicate the importance of appropriate medical management. Postoperative survival rate for high-risk patients with concomitant associated diseases has been reported to be about 35% to 60% [9, 15]. Mortality rate, however, can be reduced by intensified perioperative care. As reported by Whittemore and colleagues [16], a 5-year cumulative survival rate in high-risk patients can be shifted to 84% by maintenance of optimal cardiac performance with careful attention to fluid therapy during the perioperative period. It is difficult to compare such series of patients, but available data indicate that high-risk patients with nonmalignant associated diseases may have a more favorable course if operated on as compared with about a 60% risk of dying within 2 years if not operated on.

Dissections
Most authors presently agree that acute dissections involving the ascending aorta require urgent operation [17, 18]. Debate continues, however, concerning mode of treatment for type B dissections [19, 20]. Controversies are due to discordant results regarding survival. In the present study, although there was a significant difference in survival rate for type A and type B dissections, most of the patients in both groups died within 1 year. Moreover, most of them died of rupture in both groups. In this situation, attention should be paid to individual comparisons of surgical versus nonsurgical treatment, rather than on comparison of type A with type B survivals. As mentioned, most of the patients in our study died within the first years. This finding is in contrast to a preliminary report by Masuda and colleagues [21], who reported 5-year survival rates for type A and B of 34% and 76%, respectively. This discrepancy could originate from race differences, but other reviews of nonoperated dissections from Japan [22] and the United States [19] reported 5-year survival rates of 48% to 64%, which are much closer to our findings. Another problem is a bias in the choice of treatment. Since the 1970s, there has been a tendency to follow up type B dissections conservatively as long as patients are stable and without progress of the dissection [23]. Operation is employed if patients present serious complications [19, 20]. Therefore, it is probable that survival rates for surgically treated patients with type B dissections are, in some centers, worse than for those not operated on. This also can explain the difference in survival between nonoperated type A and type B dissections. Nevertheless, the cumulative 5-year survival rate for patients with dissections of the descending thoracic aorta who were discharged from the hospital after surgical treatment is 70% to 97% [14, 24], thus about 30% to 50% higher than for similar nonoperated patients from our material.

A retrospective review raises controversies regarding the uniformity of populations compared. We are aware that our subpopulations are often different with respect to many predictors. Therefore, comparisons within our material are mainly informative. However, metaanalyses of operated versus nonoperated subgroups with corresponding risk factors minimize the possibility of undefined treatment selection biases and may indicate actuarial trends of treatment.

We conclude that because the majority of patients in all subgroups died of aneurysm rupture, all patients should be recognized as candidates for surgical treatment. The present data justify an aggressive approach to the patient with an aneurysm of 6 or more cm in diameter and type A dissections. The results suggest that type B dissections may have a more favorable course if operated on, but a prospective, randomized study is necessary to confirm this observation. We believe that older patients and those with a small aneurysm may benefit from early, elective operation.

	Acknowledgments

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
We thank Freddy E. E. Vermeulen, MD, at the Department of Cardiothoracic and Cardiovascular Surgery, St. Antonius Hospital, Nieuwegein, the Netherlands, for valuable review of the manuscript.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Presented in part at the Aortic Surgery Symposium IV, New York, NY, April 21–22, 1994.

Address reprint requests to Dr Perko, Department of Cardiothoracic Surgery R, KAS Gentofte, University of Copenhagen, Niels Andersens Ve; 65, DK-2900, Hellerup, Denmark.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Perko, M. J. Articles by Pettersson, G. Search for Related Content PubMed PubMed Citation Articles by Perko, M. J. Articles by Pettersson, G.