Syncope in acute aortic dissection: diagnostic, prognostic, and clinical implications.

BACKGROUND: Syncope is a well-recognized symptom of acute aortic dissection, often indicating the development of dangerous complications such as cardiac tamponade.

SUBJECTS AND METHODS: We identified consecutive patients with acute aortic dissection at 18 referral centers in six countries. Data on key clinical findings and outcomes were collected via extensive questionnaires. Multiple logistic regression models were used to determine the association between syncope and in-hospital mortality, adjusting for demographic characteristics, dissection type, comorbid conditions, and complications (e.g., cardiac tamponade).

RESULTS: Syncope was reported in 96 (13%) of 728 patients. Patients with syncope were more likely to die in the hospital (34% [n = 33 deaths]) than were those without syncope (23% [144/632], P = 0.01). They were also more likely to have cardiac tamponade (28% [n = 27] vs. 8% [n = 49], P <0.001), stroke (18% [n = 17] vs. 4% [n = 27], P <0.001), and other neurologic deficits (25% [n = 24] vs. 14% [n = 88], P = 0.005). After multivariate adjustment, clinical factors independently associated with the occurrence of syncope included a proximal dissection (odds ratio [OR] = 5.5; 95% confidence interval [CI]: 2.5 to 12; P <0.001), cardiac tamponade (OR = 3.1; 95% CI: 1.7 to 5.4; P <0.001), and stroke (OR = 3.5; 95% CI: 1.7 to 7.2; P = 0.001). There was a significant association between in-hospital death and syncope after adjustment for demographic characteristics alone (OR = 2.0; 95% CI: 1.2 to 3.5; P = 0.01), but not after adjustment for dissection type, comorbid conditions, and complications.

CONCLUSION: Patients with dissections complicated by cardiac tamponade or stroke are significantly more likely to present with syncope. If these complications are excluded, syncope alone does not appear to increase the risk of death independently.