Controversy Over Study Questioning EVAR Safety

A study on the potential risks of endovascular repair of abdominal aortic aneurysms used outside the guidelines has caused controversy. The analysis, published in Circulation, found a high incidence of aneurysm sac enlargement after stenting, which the authors tied to an increased risk of aneurysm rupture.

In an accompanying editorial, Dr. Richard P. Cambria contrasted the authors' results with the demonstrated safety of EVAR as seen in clinical trials and practice, and he proposed several trial-related factors to explain the discrepancy.

In the study, Dr. Andres Schanzer of the University of Massachusetts, and his colleagues at the Harvard School of Public Health, Boston, and the Cleveland Clinic Foundation conducted a retrospective analysis of EVAR patients in M2S Inc.'s database.

M2S served as the core imaging laboratory for several large aneurysm management trials and provides these services to public and private academic hospitals globally. The study population consisted of 10,228 patients who underwent EVAR for AAA repair in 1999-2008, and who had a baseline CT scan before EVAR and at least one follow-up CT scan. The patients were primarily men (84.1%) with a mean age of 73.9 years.

Dr. Cambria

They concluded that the majority of patients receiving endovascular repair for an aortic abdominal aneurysm failed to meet criteria for intervention as opposed to surveillance, and that more than 58% of these patients failed to meet conservative criteria for device use based on manufacturer instructions, according to a retrospective database study.

In addition, at 5 years post EVAR, 41% of the patients showed aneurysm sac enlargement, an outcome that the researchers considered a surrogate for potential aneurysm rupture, according to their report now published in print in the June 21 issue of Circulation.

The online "ahead-of-print edition" was summarized in the May Vascular Specialist (Vol 7 No.3 p.1).

In an editorial commentary on the article titled "Endovascular Repair of Abdominal Aortic Aneurysms: No Cause for Alarm," Dr. Richard P. Cambria, current president of the Society for Vascular Surgery, presents a critique of several of the points raised by Dr. Schanzer and his colleagues and comes to the overall conclusion that "The concerns raised in the Schanzer et al. report are, in a sense, legitimate, yet the preponderance of evidence has verified the clinical efficacy of EVAR" (Circulation 2011; 123:2782-3). For example, a large longitudinal study of EVAR in Medicare beneficiaries showed late AAA rupture after EVAR to be a rare event (1.8% at 4 years).

Dr. Cambria took issue with several key points in the article.

Perhaps the most import was the fact that the "alarmingly high" incidence of post-EVAR sac enlargement (17% at 3 years and 41% at 5 years) seen by Dr. Schanzer's group was dramatically higher than seen in other studies and went in the face of a "surfeit of literature encompassing single center cohort studies, registries/trials, and even randomized trials of EVAR verses open repair for AAA," all of which have verified the clinical effectiveness of EVAR.

Dr. Cambria pointed out that in his own group only 8% of sequentially imaged post-EVAR patients demonstrated sac enlargement at 3 years, and in the Eurostar registry, the figure was in the 10% range. In addition, in device-specific trials the rate of sac enlargement ranged from 5% to 12%.

In addition, the significance of sac enlargement after EVAR in the absence of endoleak has been doubted because of a lack of correlation with clinically significant outcomes.

Dr. Cambria indicated that the probable reason for the much higher overall incidence of sac enlargement seen by the authors as compared to the literature is due to an inherent selection bias caused by the study considering only those patients whose surgeons sought further information post-EVAR using an expensive computed tomography scan, typically only obtained when there is some question about the technical results of the EVAR. "Accordingly the denominator in the Schantzer et al. study is unknown, and herein lies the explanation for their AAA sac enlargement data."

With regard to the high incidence of EVAR performed outside the recommended instructions for use (IFU) reported by the authors, Dr. Cambria indicated that the binary nature in which they addressed the question (as liberal or conservative applications) "tends to overestimate the number of procedures performed outside of IFU." Dr. Cambria also stated that in high-risk (for open repair) patients, surgeons "frequently and intentionally compromise on IFU guidelines simply because that is appropriate clinical decision-making."

In addition, "although a general recommendation to adhere to IFU considerations in EVAR is appropriate, favorable results have been achieved when less stringent criteria are applied in accordance with individual patient considerations."

The issue of inappropriate treatment with EVAR of patients with AAA size under the 5.5 cm threshold was also addressed.

"In my view... the article's tone is overly harsh in its implication that the 60% of EVAR patients treated with AAAs less than or equal to 5.5 cm were incorrectly managed." He pointed out that Society for Vascular Surgery guidelines specifically indicate that a variety of clinical and/or anatomic features (not to mention patient preference) clearly influence the decision to proceed with treatment "particularly for AAAs in the 5.0-cm to 5.5-cm range."

He also pointed out that larger AAAs are less likely to be anatomically suitable for EVAR.

Dr. Schanzen and his colleagues reported that they had no disclosures.

Dr. Cambria reported receiving research support in the context of participation in clinical trials from W.L. Gore, Cook, and Medtronic.

A study on the potential risks of endovascular repair of abdominal aortic aneurysms used outside the guidelines has caused controversy. The analysis, published in Circulation, found a high incidence of aneurysm sac enlargement after stenting, which the authors tied to an increased risk of aneurysm rupture.

In an accompanying editorial, Dr. Richard P. Cambria contrasted the authors' results with the demonstrated safety of EVAR as seen in clinical trials and practice, and he proposed several trial-related factors to explain the discrepancy.

In the study, Dr. Andres Schanzer of the University of Massachusetts, and his colleagues at the Harvard School of Public Health, Boston, and the Cleveland Clinic Foundation conducted a retrospective analysis of EVAR patients in M2S Inc.'s database.

M2S served as the core imaging laboratory for several large aneurysm management trials and provides these services to public and private academic hospitals globally. The study population consisted of 10,228 patients who underwent EVAR for AAA repair in 1999-2008, and who had a baseline CT scan before EVAR and at least one follow-up CT scan. The patients were primarily men (84.1%) with a mean age of 73.9 years.

Dr. Cambria

They concluded that the majority of patients receiving endovascular repair for an aortic abdominal aneurysm failed to meet criteria for intervention as opposed to surveillance, and that more than 58% of these patients failed to meet conservative criteria for device use based on manufacturer instructions, according to a retrospective database study.

In addition, at 5 years post EVAR, 41% of the patients showed aneurysm sac enlargement, an outcome that the researchers considered a surrogate for potential aneurysm rupture, according to their report now published in print in the June 21 issue of Circulation.

The online "ahead-of-print edition" was summarized in the May Vascular Specialist (Vol 7 No.3 p.1).

In an editorial commentary on the article titled "Endovascular Repair of Abdominal Aortic Aneurysms: No Cause for Alarm," Dr. Richard P. Cambria, current president of the Society for Vascular Surgery, presents a critique of several of the points raised by Dr. Schanzer and his colleagues and comes to the overall conclusion that "The concerns raised in the Schanzer et al. report are, in a sense, legitimate, yet the preponderance of evidence has verified the clinical efficacy of EVAR" (Circulation 2011; 123:2782-3). For example, a large longitudinal study of EVAR in Medicare beneficiaries showed late AAA rupture after EVAR to be a rare event (1.8% at 4 years).

Dr. Cambria took issue with several key points in the article.

Perhaps the most import was the fact that the "alarmingly high" incidence of post-EVAR sac enlargement (17% at 3 years and 41% at 5 years) seen by Dr. Schanzer's group was dramatically higher than seen in other studies and went in the face of a "surfeit of literature encompassing single center cohort studies, registries/trials, and even randomized trials of EVAR verses open repair for AAA," all of which have verified the clinical effectiveness of EVAR.

Dr. Cambria pointed out that in his own group only 8% of sequentially imaged post-EVAR patients demonstrated sac enlargement at 3 years, and in the Eurostar registry, the figure was in the 10% range. In addition, in device-specific trials the rate of sac enlargement ranged from 5% to 12%.

In addition, the significance of sac enlargement after EVAR in the absence of endoleak has been doubted because of a lack of correlation with clinically significant outcomes.

Dr. Cambria indicated that the probable reason for the much higher overall incidence of sac enlargement seen by the authors as compared to the literature is due to an inherent selection bias caused by the study considering only those patients whose surgeons sought further information post-EVAR using an expensive computed tomography scan, typically only obtained when there is some question about the technical results of the EVAR. "Accordingly the denominator in the Schantzer et al. study is unknown, and herein lies the explanation for their AAA sac enlargement data."

With regard to the high incidence of EVAR performed outside the recommended instructions for use (IFU) reported by the authors, Dr. Cambria indicated that the binary nature in which they addressed the question (as liberal or conservative applications) "tends to overestimate the number of procedures performed outside of IFU." Dr. Cambria also stated that in high-risk (for open repair) patients, surgeons "frequently and intentionally compromise on IFU guidelines simply because that is appropriate clinical decision-making."

In addition, "although a general recommendation to adhere to IFU considerations in EVAR is appropriate, favorable results have been achieved when less stringent criteria are applied in accordance with individual patient considerations."

The issue of inappropriate treatment with EVAR of patients with AAA size under the 5.5 cm threshold was also addressed.

"In my view... the article's tone is overly harsh in its implication that the 60% of EVAR patients treated with AAAs less than or equal to 5.5 cm were incorrectly managed." He pointed out that Society for Vascular Surgery guidelines specifically indicate that a variety of clinical and/or anatomic features (not to mention patient preference) clearly influence the decision to proceed with treatment "particularly for AAAs in the 5.0-cm to 5.5-cm range."

He also pointed out that larger AAAs are less likely to be anatomically suitable for EVAR.

Dr. Schanzen and his colleagues reported that they had no disclosures.

Dr. Cambria reported receiving research support in the context of participation in clinical trials from W.L. Gore, Cook, and Medtronic.

A study on the potential risks of endovascular repair of abdominal aortic aneurysms used outside the guidelines has caused controversy. The analysis, published in Circulation, found a high incidence of aneurysm sac enlargement after stenting, which the authors tied to an increased risk of aneurysm rupture.

In an accompanying editorial, Dr. Richard P. Cambria contrasted the authors' results with the demonstrated safety of EVAR as seen in clinical trials and practice, and he proposed several trial-related factors to explain the discrepancy.

In the study, Dr. Andres Schanzer of the University of Massachusetts, and his colleagues at the Harvard School of Public Health, Boston, and the Cleveland Clinic Foundation conducted a retrospective analysis of EVAR patients in M2S Inc.'s database.

M2S served as the core imaging laboratory for several large aneurysm management trials and provides these services to public and private academic hospitals globally. The study population consisted of 10,228 patients who underwent EVAR for AAA repair in 1999-2008, and who had a baseline CT scan before EVAR and at least one follow-up CT scan. The patients were primarily men (84.1%) with a mean age of 73.9 years.

Dr. Cambria

They concluded that the majority of patients receiving endovascular repair for an aortic abdominal aneurysm failed to meet criteria for intervention as opposed to surveillance, and that more than 58% of these patients failed to meet conservative criteria for device use based on manufacturer instructions, according to a retrospective database study.

In addition, at 5 years post EVAR, 41% of the patients showed aneurysm sac enlargement, an outcome that the researchers considered a surrogate for potential aneurysm rupture, according to their report now published in print in the June 21 issue of Circulation.

The online "ahead-of-print edition" was summarized in the May Vascular Specialist (Vol 7 No.3 p.1).

In an editorial commentary on the article titled "Endovascular Repair of Abdominal Aortic Aneurysms: No Cause for Alarm," Dr. Richard P. Cambria, current president of the Society for Vascular Surgery, presents a critique of several of the points raised by Dr. Schanzer and his colleagues and comes to the overall conclusion that "The concerns raised in the Schanzer et al. report are, in a sense, legitimate, yet the preponderance of evidence has verified the clinical efficacy of EVAR" (Circulation 2011; 123:2782-3). For example, a large longitudinal study of EVAR in Medicare beneficiaries showed late AAA rupture after EVAR to be a rare event (1.8% at 4 years).

Dr. Cambria took issue with several key points in the article.

Perhaps the most import was the fact that the "alarmingly high" incidence of post-EVAR sac enlargement (17% at 3 years and 41% at 5 years) seen by Dr. Schanzer's group was dramatically higher than seen in other studies and went in the face of a "surfeit of literature encompassing single center cohort studies, registries/trials, and even randomized trials of EVAR verses open repair for AAA," all of which have verified the clinical effectiveness of EVAR.

Dr. Cambria pointed out that in his own group only 8% of sequentially imaged post-EVAR patients demonstrated sac enlargement at 3 years, and in the Eurostar registry, the figure was in the 10% range. In addition, in device-specific trials the rate of sac enlargement ranged from 5% to 12%.

In addition, the significance of sac enlargement after EVAR in the absence of endoleak has been doubted because of a lack of correlation with clinically significant outcomes.

Dr. Cambria indicated that the probable reason for the much higher overall incidence of sac enlargement seen by the authors as compared to the literature is due to an inherent selection bias caused by the study considering only those patients whose surgeons sought further information post-EVAR using an expensive computed tomography scan, typically only obtained when there is some question about the technical results of the EVAR. "Accordingly the denominator in the Schantzer et al. study is unknown, and herein lies the explanation for their AAA sac enlargement data."

With regard to the high incidence of EVAR performed outside the recommended instructions for use (IFU) reported by the authors, Dr. Cambria indicated that the binary nature in which they addressed the question (as liberal or conservative applications) "tends to overestimate the number of procedures performed outside of IFU." Dr. Cambria also stated that in high-risk (for open repair) patients, surgeons "frequently and intentionally compromise on IFU guidelines simply because that is appropriate clinical decision-making."

In addition, "although a general recommendation to adhere to IFU considerations in EVAR is appropriate, favorable results have been achieved when less stringent criteria are applied in accordance with individual patient considerations."

The issue of inappropriate treatment with EVAR of patients with AAA size under the 5.5 cm threshold was also addressed.

"In my view... the article's tone is overly harsh in its implication that the 60% of EVAR patients treated with AAAs less than or equal to 5.5 cm were incorrectly managed." He pointed out that Society for Vascular Surgery guidelines specifically indicate that a variety of clinical and/or anatomic features (not to mention patient preference) clearly influence the decision to proceed with treatment "particularly for AAAs in the 5.0-cm to 5.5-cm range."

He also pointed out that larger AAAs are less likely to be anatomically suitable for EVAR.

Dr. Schanzen and his colleagues reported that they had no disclosures.

Dr. Cambria reported receiving research support in the context of participation in clinical trials from W.L. Gore, Cook, and Medtronic.