Study of Four Aortic Root Procedures Finds All to Be Safe, Durable

Four common aortic root procedures — valve preservation, composite graft with mechanical valve, composite graft with biological valve, and allograft — offer excellent long-term survival and good durability for patients with aneurysms. So finds a large Cleveland Clinic study presented today at the 95th Annual Meeting of the American Association for Thoracic Surgery that compared outcomes of the four surgical strategies.

“Valve-preserving and allograft procedures produced the lowest gradients but tended to result in late regurgitation,” says lead study author Lars G. Svensson, MD, PhD, Chairman of Cleveland Clinic’s Sydell and Arnold Miller Family Heart & Vascular Institute. “Despite such tradeoffs, we recommend valve-preserving procedures for young patients when possible, while composite bioprostheses are reasonable for the elderly.”

Aortic root procedures: Knowns and unknowns

Valve-preserving aortic root procedures have become increasingly popular, with good results lasting longer than 10 years. The authors previously showed that reimplantation for tricuspid aortic valves and repair of bicuspid valves resulted in superior durability over time, compared with biologic composite valves.

Additionally, newer techniques for bicuspid valve repair, including higher commissure implantation, have resulted in a low risk of death (0.47 percent) and stroke (0.25 percent) and better long-term durability. However, how these procedures compared with mechanical composite grafts or allografts was unknown.

Study design

The study examined the outcomes of 957 patients who underwent nonemergent aortic root surgery for aneurysms at Cleveland Clinic between January 1995 and January 2011. In each case, the choice of procedure was determined by the surgeon in consultation with the patient.

End points were as follows:

• In-hospital postoperative morbidity and mortality
• Aortic valve function over time
• Left ventricular reverse remodeling
• Aortic reoperations
• Short- and long-term mortality

Patient characteristics by procedure type

Patients who underwent a valve-preserving procedure tended to be younger and to have lower rates of regurgitation, stenosis and left ventricular dysfunction. They had large aneurysms but were less likely to have a bicuspid valve, valve calcification or heart failure.

Patients who received a biologic composite graft tended to be older and more symptomatic and to have more ventricular hypertrophy.

Over the course of the study, valve-preserving and biologic composite graft procedures increased in number, mechanical composite graft procedures declined, and allograft procedures remained stable.

Patient outcomes

Across the overall study population, aortic root surgery resulted in a 0.73 percent in-hospital mortality rate and a 1.4 percent stroke rate. Rates of death and stroke were similar among procedure types. There were no in-hospital deaths among patients receiving valve-preserving procedures.

Valve-preserving and allograft procedures produced lower early mean gradients than composite grafts with either biologic or mechanical valves. “The net result was that left ventricular remodeling was most successful with valve preservation,” says Dr. Svensson.

Aortic valve regurgitation increased over time, particularly in the valve-preservation and allograft groups. More regurgitation was seen following composite graft replacement with a mechanical valve than with a biologic valve. Although valve-related complications were not fully examined, valve-preserving procedures and allografts were less likely to cause bleeding, hemorrhage and endocarditis.

Freedom from reoperation varied by strategy and by early vs. late reoperation. The risk of early reoperation was highest with valve preservation and lowest with allograft replacement. The risk of late reoperation was highest with allograft replacement and lowest with composite mechanical graft replacement and valve preservation.

“The downside of valve preservation was early risk of reoperation, although this was specifically related to the remodeling of bicuspid valves,” notes Dr. Svensson. “Reimplantation of tricuspid aortic valves provided excellent results.”

Recommendations for practice

Based on these findings, the team of Cleveland Clinic researchers recommends the following aortic root procedures for different types of aneurysms and patients:

• Valve preservation by reimplantation for tricuspid nonstenotic aortic valves
• Valve preservation by remodeling for bicuspid nonstenotic valves
• Composite graft replacement with a mechanical valve for young patients with a stenotic aortic valve
• Composite graft replacement with a biologic valve for elderly patients with a stenotic aortic valve
• Allograft root and ascending aorta replacement with coronary reimplantation for patients with endocarditis — and perhaps for elderly patients with a small aortic annulus

“With the exception of cases of endocarditis, we continue to advocate valve preservation and biologic composite grafts as preferable to allografts,” Dr. Svensson says.