PC038. A Natural History of Acute Type B Aortic Dissections in Northern California

To date, population-based data on the incidence and long-term outcomes of acute type B aortic dissection are limited. This study sought to define the incidence and long-term outcomes of acute type B dissections in a large northern California health care maintenance organization. All patients with health plan membership between January 1, 2008, and December 31, 2015, were retrospectively reviewed with acute type B dissection at the first occurrence (index event). Demographics (age, sex, and race/ethnicity) and clinical information (medical history and Charlson Comorbidity Index) were collected. The primary exposure was the presence or absence of operative intervention (endovascular, open, or hybrid) on index event or during follow-up. The primary outcome was mortality. Trend analysis of incidence by year was assessed using ordinal logistic regression. A multivariable Cox proportional hazards model was used to calculate adjusted hazard ratio and 95% confidence interval for associations between operative intervention and mortality. Among 277 patients identified with acute type B aortic dissections between 2008 and 2015, the mean age was 66 (±14) years, and 166 (59.9%) were male. Incidence of type B dissections remained consistent during the study period, with a range of 11.5 to 20.3 cases per 1,000,000 individuals (P = .3). The mean follow-up was 4.2 (±2.7) years. Overall crude mortality rate was 7.2 per 100 person-years, with 30-day mortality being 6.1%; 1-year, 11.9%; 3-year, 18.1%; 5-year, 23.8%; and 10-year, 30.3%. Fifty-seven (20.6%) patients underwent operative intervention (7 open, 41 endovascular, 9 hybrid). No significant association was detected between operative intervention and overall mortality (hazard ratio, 0.9; 95% confidence interval, 0.5-1.6); however, those with operative management tended to have longer term survival (Fig). During follow-up and among those who died (n = 84), causes of death were cardiac related in 26 (31%), aortic related in 21 (25%), noncardiac in 19 (22.7%), and unknown in 18 (21%). This study of acute type B dissections is one of the largest population-based studies to date with long-term follow-up. Whereas 30-day mortality is lower than previously reported rates, long-term mortality with and without operation remains high. Additional analyses of this data set will be critical to further understand type B dissection management and outcomes.