Acute Aortic Dissection: Population-Based Incidence Compared with Degenerative Aortic Aneurysm Rupture

Objectives: To ascertain whether acute aortic dissection (AAD) remains the most common aortic catastrophe, as generally believed, and to detect any improvement in outcomes compared with previously reported population-based data. Patients and Methods: We determined the incidence, operative intervention rate, and long-term survival rate of Olmsted County, Minnesota, residents with a clinical diagnosis of AAD initially made between 1980 and 1994. The incidence of degenerative thoracic aortic aneurysm (TAA) rupture was also delineated. We compared these results with other population-based studies of AAD, degenerative TAA, and abdominal aortic aneurysm (AAA) rupture. Results: During a 15-year period, we identified 177 patients with thoracic aortic disease. We focused on 39 patients with AAD (22% of the entire cohort) and 28 with TAA rupture (16%). The annual age- and sex-adjusted incidences were 3.5 per 100,000 persons (95% confidence interval, 2.4-4.6) for AAD and 3.5 per 100,000 persons (95% confidence interval, 2.2-4.9) for TAA rupture. Thirty-three dissections (85%) involved the ascending aorta, whereas 6 (15%) involved only the descending aorta. Nineteen patients (49%) underwent 22 operations for AAD, with a 30-day case fatality rate of 9%. Among all 39 patients with AAD, median survival was only 3 days. Overall 5-year survival for those with AAD improved to 32% compared with only 5% in this community between 1951 and 1980. Conclusions: In other studies, the annual incidences of TAA rupture and AAA rupture are estimated at approximately 3 and 9 per 100,000 persons, respectively. This study indicates that AAD and ruptured degenerative TAA occur with similar frequency but less commonly than ruptured AAA. Although timely recognition and management remain problematic, these new data suggest that recent diagnostic and operative advances are improving long-term survival in AAD.