The IRAD classification system for characterizing survival after aortic dissection

Background: The classification of aortic dissection into acute (<14 days from symptom onset) versus chronic (≥14 days) is based on survival estimates of patients treated decades before modern diagnostic and treatment modalities were available. A new classification of aortic dissection in the current era may provide clinicians with a more precise method of characterizing the interaction of time, dissection location, and treatment type with survival. Methods: We developed separate Kaplan-Meier survival curves for Type A and Type B aortic dissection using data from the International Registry of Aortic Dissection (IRAD). Daily survival was stratified based on type of therapy provided: medical therapy alone (medical), nonsurgical intervention plus medical therapy (endovascular), and open surgery plus medical therapy (surgical). The log-rank statistic was used to compare the survival curves of each management type within Type A and Type B aortic dissection. Results: There were 1815 patients included, 67.3% male with mean age 62.0 ± 14.2 years. When survival curves were constructed, 4 distinct time periods were noted: hyperacute (symptom onset to 24 hours), acute (2-7 days), subacute (8-30 days), and chronic (>30 days). Overall survival was progressively lower through the 4 time periods. Conclusions: This IRAD classification system can provide clinicians with a more robust method of characterizing survival after aortic dissection over time than previous methods. This system will be useful for treating patients, counseling patients and families, and studying new diagnostic and treatment methods.