Editor's Note: This Expert Analysis is part of a series presenting perspectives on major ACC.19 trials. Please follow this link for the companion articles.

Acute aortic dissection (AAD) continues to be one of the most lethal cardiovascular conditions. Effective management requires timely diagnosis and rapid treatment, yet even under ideal circumstances morbidity and mortality remain high. Quality improvement in AAD management has been limited by the emergent nature in which AADs present as well as the low incidence of AAD relative to conditions such as acute coronary syndrome. As such, the International Registry of Acute Aortic Dissection (IRAD) was developed in 1996 to better improve outcomes with AAD.

As a consortium of over 55 large referral centers from 13 countries, IRAD maintains data on approximately 9,000 AAD patients. At ACC.19, Dr. Kim Eagle presented an overview of AAD over the past 25 years on behalf of the IRAD investigators. To describe trends over time, patients were divided into three tertiles. Hypertension, smoking and atherosclerosis were the three most common risk factors, with the frequency of hypertension increasing to 81.5% in the most recent tertile. Most type A dissections were diagnosed by CT scan and surgical management increased significantly to 88.6% in the past five years while the frequency of pre-operative stroke decreased to 3.9%. Importantly, for type A dissection patients, the overall in-hospital mortality in the most current time period decreased significantly to 16.3%. This decrease was driven by a significant decline in the in-hospital mortality rate for surgically managed patients to 13.0%. In-hospital mortality with medical management remained unchanged at 50.7%. Despite an improvement in in-hospital mortality, 5-year post-discharge survival remained unchanged at 88.5% in the most current tertile. Risk factors associated with long-term survival included age ≥70, post-procedural stroke and post-procedural tamponade.

In addition to data on type A aortic dissections, IRAD maintains data on patients presenting with type B aortic dissections. Using a similar analytic approach, the authors demonstrated that over the past 25 years there has been a shift in management trends for type B dissections to less surgical management (6.1%), less medical management (60.7%) and more endovascular management (31.2%). Like type A dissections, there was a significant decline in the in-hospital mortality to 7.4%, however, there was also a decline in 5-year post-discharge survival to 83.7%. Significant risk factors for long-term survival included age ≥70, peri-procedural spinal cord ischemia, peri-procedural renal failure and a history of chronic obstructive pulmonary disease.

The IRAD investigators are to be congratulated for their dedication to creating and maintaining an international collaboration dedicated to AAD over the past 25 years. The data presented by Dr. Eagle and colleagues at ACC.19 provide valuable insights into AAD trends. Importantly, the investigators demonstrate that outcomes with AAD are improving for both type A and B dissections. These findings are likely secondary to improvements in peri-procedural and intra-operative surgical and medical management that have occurred over time. The IRAD data also highlight areas that need continued improvement and further research over the next decade. During the study period, the time from admission to diagnosis of AAD did not changed and remained at nearly 3 hours. Moreover, while surgery for type A dissections increased, the time from admission to surgery remained unchanged at 6 hours in the most current time period. These data highlight the importance and challenge of timely diagnosis in AAD, which is often in the differential diagnosis of more common disorders such as acute coronary syndrome or pulmonary embolism. Also, these data highlight the need for more expeditious surgical intervention. Lee and colleagues examined acute type A dissection outcomes in the Society of Thoracic Surgeons (STS) adult cardiac surgery database from July 2011 to September 2012. Among 1140 centers in the North America reporting to the STS database, only 56% of centers performed one or more acute aortic dissection repair and only 11% performed 10 or more cases, with a median of three cases per center. These data highlight the fact that delays in surgical management may be partially due to access and transportation from referral hospitals to larger cardiac surgical centers. Improvements in diagnostic time and access to surgical care is one major area where quality improvement can occur.

In addition to improvements in access and management of AAD patients, the IRAD data highlight several areas of uncertainty in the field that require additional research. The IRAD investigators reported that 59.2% of patients with a type A dissection had an aortic diameter ≤ 5 cm. With current ACC guidelines recommending aortic replacement at diameters at or above 5.5 cm for most patients, there are clearly factors beyond crude size that influence dissection risk. Better risk prediction either through functional imaging or biomarkers will be necessary to more appropriately identify patients who could benefit from prophylactic aortic surgery. In addition, despite improvements in the in-hospital mortality rate for type A dissections, the long-term survival has not changed. These data highlight the need for ongoing aggressive medical management and longitudinal surveillance imaging for which there is a lack of consensus guidelines.

Outcomes with AAD have improved over the past 25 years; however, there continues to be room for significant improvement in the diagnosis, management and identification of patients at risk. IRAD has done excellent work in describing trends in outcomes and identifying areas for quality improvement initiatives and scientific research. Now we must utilize IRAD data to continue to improve survival for AAD patients.

References

1. Eagle KA. Acute aortic dissection: lessons learned from 9000 patients. American College of Cardiology Scientific Session, New Orleans, LA. March 18, 2019.
2. Lee TC, Kon Z, Cheema FH, et al. Contemporary management and outcomes of acute type A aortic dissection: an analysis of the STS adult cardiac surgery database. J Card Surg 2018;33:7-18.

Keywords: Acute Coronary Syndrome, Acute Kidney Injury, Aneurysm, Dissecting, Aortic Aneurysm, Aorta, Aortic Valve Insufficiency, Aortic Valve, Aortic Valve Stenosis, Arrhythmias, Cardiac, Arterial Pressure, Atherosclerosis, Atrial Appendage, Atrial Fibrillation, Bicuspid, Biomarkers, Cardiac Surgical Procedures, Constriction, Pathologic, Constriction, Pathologic, Conversion to Open Surgery, Coronary Artery Bypass, Coronary Disease, Creatinine, Diagnosis, Differential, Disease-Free Survival, Dilatation, Echocardiography, Endovascular Procedures, Factor VII, Follow-Up Studies, Heart Defects, Congenital, Heart Transplantation, Heart Failure, Heart Valve Diseases, Heart Valve Prosthesis, Heart-Assist Devices, Hemodynamics, Hemorrhage, Hospital Mortality, Hospitalization, Hypertension, Hypertension, Pulmonary, Length of Stay, Liver Diseases, Mitral Valve, Mitral Valve Stenosis, Mitral Valve Insufficiency, Pacemaker, Artificial, Patient Selection, Percutaneous Coronary Intervention, Prospective Studies, Pulmonary Disease, Chronic Obstructive, Pulmonary Embolism, Pulmonary Veins, Pulsatile Flow, Quality Improvement, Quality of Life, Referral and Consultation, Registries, Reoperation, Renal Insufficiency, Research Personnel, Respiratory Insufficiency, Risk Factors, Smoking, Sodium, Spinal Cord Ischemia, Stroke, Stroke Volume, Surgeons, Surgical Instruments, Thrombosis, Tomography, X-Ray Computed, Transcatheter Aortic Valve Replacement, Treatment Outcome, Tricuspid Valve Insufficiency, Ventricular Dysfunction, Left, ACC Annual Scientific Session, ACC19

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