NEW YORK – While overall guidelines for aortic repair surgery have not changed significantly in the past 5 years, guidelines for the timing of surgery in patients with bicuspid aortic valves and enlarged aortas have undergone some updating in an attempt to clear up disparities in different guidelines on when to operate on those patients.
Lars G. Svensson, MD, PhD, chairman of the Cleveland Clinic Heart and Vascular Institute, coauthor of the clarification statement by the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines (J Thorac Cardiovasc Surg. 2016;151:959-66), reported on the guidelines clarification at the meeting sponsored by the American Association for Thoracic Surgery. He noted that five different clinical guidelines between 2010 and 2014 recommended five different size thresholds for prophylactic aortic root or ascending aortic surgery in the setting of bicuspid aortic valve (BAV), ranging from 4 cm to greater than 5.5 cm. “This created a bit of a quandary and controversy between different guidelines and time periods,” he said.
Dr. Lars G. Svensson
Dr. Svensson and Loren Hiratzka, MD, medical director of cardiac surgery for TriHealth in Cincinnati, and their colleagues drafted the guideline clarification that makes the following recommendations for aortic root and ascending aorta repair or replacement when patients have BAV (strength of recommendation):
• Surgery is indicated to replace the aortic root or ascending aorta in asymptomatic patients with BAV if the diameter of the aortic root or ascending aorta is 5.5 cm or greater (Class 1).
• Surgical repair is indicated for asymptomatic patients with BAV if the root or ascending aorta diameter is 5 cm or greater in two scenarios: if the patient has an additional risk factor for dissection, such as family history or excessive aortic growth rate; or if the patient is a low surgical risk and has access to an experienced surgeon at a high-volume center (Class IIa).
The guideline update also addresses BAV in patients with Turner syndrome. The 2010 joint guidelines of 10 societies left some questions with regard to surgery in these patients, Dr. Svensson said. The established guidelines included a Class IIb recommendation for imaging of the heart and aorta to help determine the aorta risk in patients with Turner syndrome who had additional risk factors, including BAV, aortic coarctation and/or hypertension, or were planning a pregnancy.
The updated guideline includes Class IIa recommendation that in short-statured patients with Turner syndrome and BAV, measurement of the aortic root or ascending aorta diameter may not predict the dissection risk as well as aortic diameter index greater than 2.5 cm/m2. The updated recommendations also draw on one study that reported that in patients with BAV, a maximum aortic cross-sectional area-to-height ratio of 10 cm2/m or greater was also predictive of aortic dissection. (Ann Thorac Surg. 2015;100:1666-73)
The updated recommendations for open surgery for ascending aortic aneurysm include separate valve and ascending aortic replacement in patients without significant aortic root dilatation or in elderly patients, or in younger patients with minimal dilatation who have aortic valve disease; and excision of the sinuses of Valsalva with a modified David reimplantation when technically feasible in patients with connective tissue disease and others with dilatation of the aortic root and sinuses. For patients in whom the latter procedure is not feasible, root replacement with valved graft conduit would be indicated, Dr. Svensson said.
Dr. Svensson also reported on recent studies that validated recommendations in established guidelines.
Studies of circulatory arrest practices in aortic arch surgery as prescribed by established guidelines showed confirmatory results, he said. “The one point I would make about circulatory arrest is that we found in a fairly large study of 1,352 circulatory arrest patients that we reduced the risk of stroke by 40% when we used the axillary artery with a side a graft,” he said (Ann Thorac Surg. 2004;78:1274-84). His own institution’s clinical trial of 121 patients who received antegrade or retrograde brain perfusion showed rates of 0.8% for each stroke and operative death, he said (J Thorac Cardiovasc Surg. 2015;150:1140-7).
“What was also of interest there was no difference in outcomes with antegrade vs. retrograde brain profusion,” he said. “I think protection of the brain is pretty good if you follow the fundamental principles of brain protection.”
He also reported on a recent study at his institution that documented the benefits of intrathecal papaverine (IP) for spinal cord protection during descending open and endovascular aortic repairs. In 398 aortic repairs from 2001-2009, the rates of spinal cord injury were 23% in the non-IP group vs. 7% in the IP group (P = .07) in a matched cohort.