CHICAGO – Endovascular repair of thoracic aortic aneurysms confers an immediate but short-lived survival advantage over open repair that completely disappears and then reverses 4.5 years after intervention, a study showed.
After 4.5 years, patients who underwent open repair of a thoracic aortic aneurysm had better survival than patients who underwent endovascular thoracic aneurysm repair, based on a propensity-score adjusted analysis of more than 3,000 Medicare patients.
Mitchel L. Zoler/Frontline Medical News
Dr. Justin M. Schaffer
The findings also showed a striking interhospital variability among U.S. centers performing thoracic aortic aneurysm (TAA) repair that influenced patient survival by 50%. The tertile of hospitals with the best survival outcomes collectively had a 50% reduced rate of deaths during follow-up, compared with all other hospitals, Dr. Justin M. Schaffer said at the American Heart Association scientific sessions.
“Simply by picking the right hospital, patients could reduce their mortality by half. That is pretty amazing,” said Dr. Schaffer, a cardiothoracic surgeon at Stanford (Calif.) University.
Perhaps even more notable than this undefined hospital effect was the pattern of mortality effects associated with open TAA repair, compared with thoracic endovascular aortic repair (TEVAR). For these analyses, Dr. Schaffer and his associates focused on the 1,037 Medicare beneficiaries who underwent open repair of an isolated, nonruptured TAA during 1999-2011, and 2,010 similar patients treated with TEVAR during the same period. It was relatively uncommon for patients to need repair for a TAA that was neither ruptured nor presented with another cardiac problem. This subgroup constituted 19% of all open TAA repairs on Medicare patients during those years, and 25% of all TEVARs performed.
Comparison of the TEVAR and open repair patients showed that those who underwent TEVAR were older and had consistently higher prevalence rates of a long list of comorbidities, including diabetes, chronic kidney disease, atrial fibrillation, and heart failure. The two populations also showed substantial differences for several other potential confounders. To adjust for all these, the researchers used a form of propensity scoring to balance the variability between the TEVAR and open surgery subgroups.
After adjustment, the mortality analysis showed that immediately following TEVAR, patients had a large mortality advantage, but that this immediately began to diminish such that by about 6 months after the procedure, the instantaneous advantage from TEVAR reached zero and then began tilting toward an advantage from open surgery.
Because of TEVAR’s sizable early lead the cumulative mortality numbers took awhile to reflect this. When tallied at 12 months after the procedure, cumulative survival in the TEVAR group stood at 85%, and 75% among the open surgery patients, a statistically significant advantage for TEVAR for 1-year survival.
But at 4.5 years after the procedure, the cumulative mortality rate in the TEVAR group caught up to that in the open surgery group, and following that, the TEVAR patients had a higher cumulative mortality. At 5-year follow-up, cumulative survival was 56% in the open surgery group and 55% in the TEVAR group, a statistically significant difference, Dr. Schaffer reported.
“There is a clear trade-off” between the two repair options, he said. “If a patient’s expected survival [following surgery] is limited, then TEVAR is reasonable, and if the anatomy also makes it feasible,” he said. “But for healthier patients with better expected survival, open repair is more complete, more durable, and superior.”
Although the analysis has not yet identified the clinical factors that contribute to worse survival after TEVAR, “it appears to be a higher reintervention rate,” based on preliminary assessments of the data, Dr. Schaffer said.
The analysis also showed other factors that significantly linked with mortality among all patients, regardless of whether they underwent TEVAR or open surgery. In addition to showing significant incremental risk effects from each of a range of comorbidities, the results showed that over the period 1999-2011, patients had a progressive, relative reduction of 6% fewer deaths each year, and that centers with the highest repair volumes produced 11% fewer deaths, compared with medium-volume hospitals.
Dr. Schaffer said he had no relevant financial disclosures.
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