The Practice Pulse April 2017
Transcatheter aortic valve replacement (tavr): evolutionary or revolutionary, and what does the future hold?
Aortic stenosis in adults can have diverse etiologies. Approximately one in 250 live births is known to have a congenitally bicuspid aortic valve. Bicuspid valves have abnormal flow dynamics and can lead to either stenosis or regurgitation earlier in life than patients who are born with three leaflet valves. Rheumatic fever is a more common cause of aortic valve pathology. Although less prevalent now than it once was in the United States, it remains an etiology of stenotic aortic valves. Calcific aortic stenosis results from mainly solid calcium deposits within the valve cusps, and accounts for the vast majority of aortic stenosis. These patients most commonly present in the sixth, seventh and eighth decades of life.
Patients may develop shortness of breath, angina or chest pain, fatigue, syncope or presyncope, or palpitations as symptoms of aortic valve disease. These symptoms are commonly misunderstood by patients as normal signs of aging. Many patients initially appear asymptomatic, but on closer examination up to 37% will exhibit symptoms when placed under stress.
Perhaps most concerning is that severe aortic stenosis (AS) is a slowly progressing disease process but ultimately can become life-threatening. Often AS has a prolonged latent period during which there is increasing obstruction and myocardial overload without symptoms. In many, the initial presenting symptom may be angina, syncope, or heart failure.
After the onset of symptoms patients may have a survival rate as low as 50% at two years and 20% at five years without aortic valve replacement. A sobering perspective for inoperable patients presenting with severe aortic stenosis with symptoms that do not undergo aortic valve replacement have a five year survival rate as poor as many stage IV metastatic cancers, including breast, lung, colon, prostate, or ovarian.
Prior to the advent of TAVR technology it is estimated by multiple studies that at least 40% of severe aortic stenosis patients were not treated with aortic valve replacement. However, TAVR changes how physicians and patients approach the treatment of severe aortic stenosis.
Who should be considered for TAVR?
There are many characteristics of a TAVR patient. First, the patient must have severe symptomatic native aortic valve stenosis, or a failing bioprosthetic valve. Most patients will have a mortality risk score of 4% or greater. However, many may have additional contributing factors that may make the risk higher than the calculated mortality risk score. Additional factors of advanced age, prior history of stroke, reduced ejection fraction, prior sternal entries making reentry difficult, prior chest radiation or heavily calcified aorta, additional comorbidities, or frailty are also considered.
Evaluation of potential TAVR patients requires a collaborative structural heart team concept to be fully implemented and embraced. This multidisciplinary approach ensures patient centric care and a thorough assessment resulting in a collaborative treatment decision.
TAVR can be performed with just moderate sedation in many patients. More complex patients may required general anesthesia, but can be removed from ventilator support immediately after. The patients often spend only one evening in the hospital following TAVR.
There have been more than 80,000 TAVR implants globally since 2007, spanning more than 60 countries. In the United States the valves have been implanted since 2011 and in four different large US trials that have demonstrated ongoing noninferiority, and in some cases superiority, to the conventional operations.
The advent of TAVR valve technology is one of those rare opportunities that we encounter during our medical career to see an intervention that changes the spectrum of treatment for a disease process. While we all see many treatments throughout our career that are evolutionary, TAVR valve technology is truly revolutionary. This technology has allowed an entire cohort of patients who previously would not have been offered intervention to undergo potentially curative procedures.
Charles T. Klodell, MD
The latest murmurs
“My father recently had a TAVR done at North Florida Regional Hospital. He had been told previously that an open heart surgery would be a very high risk procedure secondary to his severe scoliosis and atypical cardiac anatomy. By postop day one he was walking in the hallways, and had already improved his exercise tolerance. The support by the TAVR team and the staff at North Florida Regional hospital was superb. I would highly recommend them to anyone who is a candidate for an aortic valve replacement.” - Dr. Ann Carr, Neurosurgeon. Daughter of patient.
“The collaborative approach to patient care has allowed our TAVR program to grow quickly. We work extremely hard as a team to optimize our patients’ experience, and our effective team communication helps to ensure we can accomplish the ultimate goal of providing the patient the best care and experience.” - Dr. William Smith, Cardiac Anesthesiologist.
Florida Heart and Lung Institute