BACKGROUND: Aortic dissection type A requires immediate surgery. In general surgery populations, patients operated on during weekends have higher mortality rates compared with patients whose operations occur on weekdays. The weekend effect in aortic dissection type A has not been studied in detail.

METHODS: The Nordic Consortium for Acute Type A Aortic Dissection (NORCAAD) registry includes data for 1,159 patients who underwent type A dissection surgery at 8 Nordic centers during 2005 to 2014. This study is based on data relating to surgery conducted during weekdays versus weekends and starting between 8:00 am and 8:00 pm ("daytime") versus from 8:00 pm to 8:00 am ("nighttime"), as well as time from symptoms, admittance, and diagnosis to surgery. The influence of timing of surgery on the 30-day mortality rate was assessed using logistic regression analysis.

RESULTS: The 30-day mortality was 18% (204 of 1,159), with no difference in mortality between surgery performed on weekdays (17% [150 of 889]) and on weekends (20% [54 of 270], p = 0.45), or during nighttime (19% [87 of 467]) versus daytime (17% [117 of 680], p = 0.54). Time from symptoms to surgery (median 7.0 hours vs 6.5 hours, p = 0.31) did not differ between patients who survived and those who died at 30 days. Multivariable regression analysis of risk factors for 30-day mortality showed no weekend effect (odds ratio, 1.04; 95% confidence interval, 60.67 to 1.60; p = 0.875), but nighttime surgery was a risk factor (odds ratio, 2.43; 95% confidence interval, 1.29 to 4.56; p = 0.006).

CONCLUSIONS: The 30-day mortality in surgical repair of aortic dissection type A was not significantly affected by timing of surgery during weekends versus weekdays. Nighttime surgery seems to predict increased 30-day mortality, after correction for other risk factors.