Surgical intervention criteria for thoracic aortic aneurysms: A study of growth rates and complications

Background. Evidence regarding the behavior of thoracic aortic aneurysm (TA A) is limited. This study reviews our ongoing efforts to understand the fac tors influencing aortic growth rates and the complications of rupture and d issection in order to define scientifically sound criteria for surgical int ervention. Methods. Data from 370 patients with TAA treated at Yale University School of Medicine from January 1985 to Tune 1997 were analyzed. This computerized data base included 1063 imaging studies (magnetic resonance imaging, compu ted tomography, and echocardiography). Results. The mean size of the thoracic aorta in these patients at initial p resentation was 5.2 cm (range 3.5-10). The mean growth rate was 0.10 cm/yea r. Median size at the time of rupture or dissection was 5.9 cm for ascendin g and 7.2 cm for descending aneurysms. The incidence of dissection or ruptu re increased with aneurysm size. Multivariable regression analysis to isola te risk factors for acute dissection or rupture revealed that size greater than or equal to 6.0 cm increased the probability of these devastating comp lications by 25.2% for ascending aneurysms (p = 0.006 compared with aneurys ms 4.0-4.9 cm). For descending aneurysms greater than or equal to 7.0 cm, r isk of dissection or rupture was increased by 37.3% (p = 0.031). Conclusions. If the median size at time of dissection or rupture had been u sed as the indication for intervention, half the patients would have suffer ed a devastating complication before surgery. Accordingly, a criterion lowe r than the median is appropriate. We recommend 5.5 cm as an acceptable size for elective resection of ascending aortic aneurysms because this operatio n can be performed with relatively low mortality. For aneurysms of the desc ending aorta, where perioperative complications are greater and the median size at the time of complication is larger, we recommend intervention at 6. 5 cm. (C) 1999 by The Society of Thoracic Surgeons.