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The Immediate Cause of Death After Surgical Repair of Acute Type A Aortic Dissection: Evidence From the Canadian Thoracic Aortic Collaborative (CTAC)
R Scott McClure, MD1, Maral Ouzounian, MD2, Munir Boodhwani, MD3, Ismail El-Hamamsy, MD4, Michael W. Chu, MD5, Zlatko Pozeg, MD6, Francois Dagenais, MD7, Jehangir J. Appoo, MD1.
1University of Calgary, Calgary, AB, Canada, 2University of Toronto, Toronto, ON, Canada, 3University of Ottawa, Ottawa, ON, Canada, 4University of Montreal, Montreal, QC, Canada, 5Western University, London, ON, Canada, 6University of Manitoba, Winnipeg, MB, Canada, 7Laval University, Quebec City, QC, Canada.
OBJECTIVES: Surgery confers the best chance at survival in acute type A dissection (ATAD), yet mortality remains high. Perioperative risk factors that predict mortality are described but data on the actual cause of death are sparse. This study aims to characterize the inciting event causing death during surgical repair of ATAD.
METHODS: Nine centres within the Canadian Thoracic Aortic Collaborative participated in the study. All patients who died in the perioperative period following surgical repair for ATAD between January 2007 and December 2013 were included. Baseline characteristics, intraoperative variables and postoperative complications were reviewed. An attending cardiac surgeon at each site verified the data and determined the cause of death, which was classified into 1 of 7 pre-determined categories (stroke, hemorrhage, cardiac, other organ ischemia, multiorgan failure, sepsis, or other). Clinical and operative variables were analyzed with respect to the inciting cause of death to delineate potential modifiable factors for mortality.
RESULTS: For 692 patients, 123 deaths were reviewed (mortality rate = 17.8%). Mean age was 65. Etiology of death was: cardiac 25%, stroke 22%, hemorrhage 22%, multiorgan failure 12%, other organ ischemia 11%, sepsis 4% and varied other causes 4%. Presenting clinical status was tamponade 27%, focal neurological injury 26%, limb ischemia 13% and known visceral ischemia 7%. Neurologic injury at presentation was a predictor of stroke as the inciting cause of death (p=0.04). As well, limb ischemia was a predictor for organ ischemia as the inciting cause of death (p=0.004). A similar association between shock, tamponade or cardiopulmonary bypass time with cardiac death was not identified. For patients without a stroke at presentation, 17% still died of stroke. Of the 123 deaths, 31% had a postoperative stroke, 26% required dialysis, 20% required re-exploration for bleeding and 7% had paraplegia.
CONCLUSIONS: Operative mortality in Canada for ATAD is similar to contemporary worldwide registry data. 70% of deaths following surgery for ATAD arise from postoperative stroke, hemorrhage, or cardiac dysfunction. Novel surgical, hybrid and endovascular strategies should target these 3 areas in an effort to improve outcomes. A further understanding of the mechanisms of stroke in this population is needed.
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