Changes in referral practice, workload, and operative mortality after establishment of an endovascular abdominal aortic aneurysm program

Risk stratification and outcomes of transluminal endografting for abdominal aortic aneurysm: 7-year experience and long-term follow-up

PURPOSE

To determine early and late outcomes of transluminal endografting (TE) in patients with abdominal aortic aneurysm (AAA), stratified by predicted risk of procedure-related mortality with conventional operation.

MATERIALS AND METHODS

A retrospective study was conducted in consecutive risk-stratified AAA patients undergoing TE at a not-for-profit cardiovascular referral center from March 1994 through November 2000 with follow-up through February 2001. With use of conventional risk strata (0 = low, 1 = minimal, 2 = moderate, and 3 = high), predicted procedure-related mortalities were 0%-1% in stratum 0 (n = 40), 1%-3% in stratum 1 (n = 118), 3%-8% in stratum 2 (n = 116), and 8%-30% in stratum 3 (n = 31). Main outcome measures were: (i) TE procedural success, (ii) procedure-related mortality, (iii) major nonfatal complications, (iv) composite adverse outcome (ii + iii), (v) length of stay (LOS), (vi) freedom from AAA rupture, (vii) late survival, (viii) late complications, and (ix) endoleaks and their classification and management.

RESULTS

Women were significantly less likely than men to qualify for and undergo endografting: 24 of 91 (26.4%) women underwent TE, compared to 281 of 684 (41.1%) men. Of 305 attempted TE procedures, 291 (95.4%) were successful, four (1.3%) were urgently converted to open repair, and 10 (3.3%) were aborted. Procedure-related mortalities occurred in eight cases (2.6%) overall and one of 40 (2.5%), one of 118 (0.8%), four of 116 (3.4%), and two of 31 (6.5%) cases for risk strata 0-3, respectively. Perioperative survivors were significantly younger than nonsurvivors (74.3 y +/- 9 vs 81.6 y +/- 5.1; P =.0087). Forty-six patients (15.1%) had major complications. Composite adverse outcome was worse for patients in stratum 3 than those in stratum 1 (P =.0296) and those in strata 0, 1, and 2 combined (P =.026). Procedure-related mortality declined with institutional experience, from 4% among the first 100 patients undergoing TE to 1% among the last 105. For strata 0-3, median LOS were 2, 3, 3, and 4 days, respectively. Seventy patients (22.9%) had 75 endoleaks, of which 30 necessitated additional procedures, 17 self-resolved, and 22 were untreated as of March 1, 2001. Five patients with endoleak died of unrelated causes. One late-onset type IA endoleak (26 mo) resulted in the only AAA rupture and death in the follow-up period among the 291 patients who underwent successful transluminal endograft implantation. Actuarial survival rates at 1 year after TE were 90.3% +/- 1.9% for the overall study group and 97.5% +/- 2.5%, 94% +/- 2.5%, 86.9% +/- 3.3%, and 81.3% +/- 7.7% for risk strata 0-3, respectively. At 5 years, overall actuarial survival was 69.6% +/- 6.1%. Thirty-eight late deaths were attributable to post-TE AAA rupture (n = 1), AAA rupture late after failed TE with no further treatment (n = 1), other cardiovascular disorders (n = 7), cancer (n = 15), other causes (n = 10), and unknown causes (n = 4). Late deaths occurred in risk strata 0-3 at the following rates: two of 40 (5%), 10 of 118 (8.5%), 16 of 116 (13.8%), and 10 of 31 (32.3%), respectively (stratum 0 vs stratum 3, P =.0017; stratum 1 vs stratum 3, P =.003).

CONCLUSIONS

TE is safe and confers durable protection against AAA rupture in treated populations. Still, protection is not absolute in patients with endoleaks, because late AAA enlargement and even rupture can occur. Given current knowledge, technology, and practice, careful patient selection and close surveillance of patients after implantation of transluminal endografts is essential.

Portsmouth POSSUM models for abdominal aortic aneurysm surgery

BACKGROUND

The Portsmouth Physiological and Operative Severity Score for enUmeration of Mortality and morbidity (P-POSSUM) equation permits comparative audit that allows for differences in case mix. The methodology has previously been shown accurately to model general surgical and vascular surgical patients. Patients with a ruptured abdominal aortic aneurysm (AAA) are, however, very different from elective patients and it may be hypothesized that they require their own specific risk model.

METHODS

POSSUM data on 444 (213 emergency, 231 elective) admissions for AAA surgery between August 1993 and July 2000 were analysed using the P-POSSUM equation for general surgery and the P-POSSUM equations developed for vascular surgery.

RESULTS

All equations successfully modelled the elective aneurysms but failed to fit the emergency aneurysms, and the elective and emergency aneurysms combined. This suggested that admission method (not a POSSUM data item) is an important factor for patients with AAA. However, with these data it was not possible to generate a model, including admission method, that successfully modelled the combined elective and emergency data. The 213 emergency aneurysm repairs were divided into two groups by operation date. The first 106 (training set) were used to form logistic regression models following the P-POSSUM methodology. These models were found successfully to fit the remaining 107 records (test set) on prospective application (chi2 = 4.50, 4 d.f., P = 0.345).

CONCLUSION

Ruptured AAAs appear to be different from elective AAAs and other vascular cases and require their own risk model.

Mortality rates following endovascular repair of abdominal aortic aneurysms

PURPOSE

To present the perioperative and late mortality following endovascular repair (EVR) of abdominal aortic aneurysms (AAAs).

METHODS

Data were collected prospectively on 221 patients undergoing AAA EVR over a 4-year period (median 5-month follow-up). Patients were classified preoperatively as high risk with at least 1 of these features: serum creatinine > 150 micromol/L, ischemic heart disease or poor left ventricular function, respiratory function < 50% of predicted normal, ruptured or symptomatic AAA, contraindication to or failed open repair, and age > 80 years.

RESULTS

One hundred forty (63.3%) patients were classified as high risk, the most common criterion being cardiac disease (n = 96, 68.6%). There were 25 (11.3%) deaths in the 30-day perioperative period, 22 (15.7%) in the high-risk group compared to 3 (3.7%) in the acceptable-risk group (p = 0.02). The most common causes of perioperative death were multisystem organ failure and myocardial infarction. A further 21 (9.5%) late deaths occurred, 16 (11.4%) in the high-risk group and 5 (6.2%) in the acceptable-risk group (p > 0.1).

CONCLUSIONS

The mortality of patients at acceptable risk undergoing EVR compares with the best published series for conventional open AAA repair. The perioperative and late mortality in the high-risk patients are substantially higher.

Physiological comparison of open and endovascular aneurysm repair

BACKGROUND

This prospective study compared morbidity and mortality rates following conventional and endovascular abdominal aortic aneurysm (AAA) repair using a physiological scoring system.

METHODS

Between December 1994 and November 1997, 104 elective open aneurysm repairs and 49 endovascular aneurysm repairs were performed. These patient cohorts were compared using the Portsmouth predictor equation (P-POSSUM) scoring system. Data collected prospectively from patient notes were used to obtain physiological and operative severity scores which were analysed to compare expected and observed mortality and morbidity rates.

RESULTS

There were three deaths (6 per cent) in the endovascular AAA repair group and 17 (16 per cent) in the conventional aneurysm repair group, whereas the P-POSSUM formulae predicted mortality rates of 8 and 19 per cent respectively. Although the mean physiological scores were similar for both groups (endovascular 20.8 versus conventional 20.1), the operative severity score was significantly greater in the conventional group (26.3 versus 19.7; P < 0.001).

CONCLUSION

In this study open aortic aneurysm repair had a higher operative severity than endovascular repair, which was reflected in the increased mortality rate.