Aortic Valve Surgery
Approximately 300,000 patients in the United States have aortic stenosis (narrowing of the aortic heart valve), and about one third of these patients are too sick or too old to undergo surgical replacement. Under the leadership of NewYork-Presbyterian Hospital's Division of Interventional Cardiology and Cardiothoracic Surgery, a new, minimally invasive method of replacing the aortic valve is under study across the U.S. This approach, called transcatheter aortic valve implantation or transcatheter aortic valve replacement (TAVI or TAVR), has shown exciting promise in the landmark PARTNER trial, which studied the safety and efficacy of the Edwards Sapien™ Aortic Valve. According to results released in the fall of 2010 and spring of 2011, transcatheter aortic valve replacement is as good as open surgery in terms of one year survival, and compared to medical management, it improves survival by 20% at one year.
During TAVR, the new aortic valve is implanted without open-heart surgery. In most patients, the new valve is inserted through the groin and advanced to the heart using a specially designed delivery catheter. The valve is positioned and implanted in the heart using x-ray for guidance. With this technique, the aortic valve can be replaced without incisions and without stopping the heart. In patients who can not have catheterization of the femoral artery due to disease in the vessels, the valve can be delivered instead through a small chest incision between the ribs. Because TAVR is done with a less invasive procedure, elderly or frail patients who could not tolerate open surgery may be able to have their aortic valves repaired this way instead.
The multicenter trial of the procedure, known as PARTNER, is one of the most important trials concerning valve disease to take place in decades. Led by Principal Investigators Craig Smith, MD, Chief, Division of Cardiothoracic Surgery and Martin B. Leon, MD, Division of Interventional Cardiology, the trial is largely conducted by faculty at the Heart Valve Center at Columbia University Medical Center, which treats patients with heart valve conditions. Investigators at NewYork-Presbyterian/Columbia include Jeffrey Moses, MD, Susheel Kodali, MD, and Mathew Williams, MD.
Dr. Smith presented the results of one segment of PARTNER (cohort A) to the American College of Cardiology 2011 Scientific Summit in New Orleans April 3, 2011.* This arm of the study found that when compared to open surgery, both TAVI and open surgery were equal in terms of one year survival. Patients who underwent transcatheter aortic valve replacement were at slightly higher risk of stroke and vascular complications, while those undergoing open surgery were at greater risk of major bleeding. "The study shows that the top 5% (high risk) patients with aortic stenosis should probably be treated with TAVI," says Dr. Smith.
The results of cohort A underscore the positive findings of the first phase of the PARTNER trial, cohort B, which were published in late 2010. This phase found that compared with medical therapy (including balloon valvuloplasty), transcatheter aortic valve replacement led to a 20% improvement in survival after one year among patients who were too sick or too old for surgery. "In addition to living longer, patients also felt much better and experienced fewer hospitalizations," says Dr. Kodali, Co-Director, Transcatheter Aortic Valve Program, NewYork-Presbyterian/Columbia Center for Interventional Vascular Therapy.
The highly positive results from both cohorts of the PARTNER trial mean that patients with aortic disease will have a new therapeutic option that works exceedingly well. Dr. Smith said in a statement that transcatheter aortic valve replacement is the most exciting new treatment for aortic stenosis in the past two to three decades.
"We already learned from the previous cohort that TAVR is the standard of care for patients who canít tolerate surgery...this [finding] opens up a new set of patients who may very well benefit as much with TAVR as with the gold standard surgery," said Dr. Smith during his presentation at the ACC.
At this time, transcatheter aortic valves are investigational devices in the US. Future studies will investigate the use of TAVI in lower risk patients. Already approved and on the market in other countries, it is expected that TAVI may gain FDA approval as early as late 2011, at least for patients ineligible for surgery. Because this procedure requires teamwork among cardiologists, surgeons, and imaging experts, it will likely become available initially at high-volume centers of excellence such as NewYork-Presbyterian/Columbia.
*Results of PARTNER cohort A will be published later in 2011.