Transcatheter Aortic Valve Implantation: State of the Art

In the last century, medical innovation has revolutionized human lives and the management of medical diseases. Conditions which were once considered untreatable are now managed and even cured. Consequently, life expectancy has dramatically increased. The aging population brings about new challenges and pathologies that must be addressed with different approaches. As the body ages, so does the heart, bringing aortic stenosis to the forefront of valvular heart disease. It is estimated that 4.6% of patients over the age of 75 years old suffer from aortic stenosis (Nkomo et al., 2006). Traditionally, there were three modalities of treatment: conservative medical management, balloon valvuloplasty, and surgical aortic valve replacement (AVR). Long considered to be the gold-standard for aortic valve stenosis, surgical intervention provided a functional valve with acceptable mortality rates. However, the risks of surgical intervention increase dramatically depending on a patient’s comorbidities. Accordingly, high-risk patients were often relegated to medical management or balloon valvuloplasty. Conservative management has yielded extremely disappointing results. Patients who underwent balloon valvuloplasty in conjunction with medical treatment had a 44-37.2% mortality rate within a year. In addition, conservative management is associated with a high rate of restenosis. Medical management alone resulted in an unacceptable 25% mortality in one year (Nkomo et al., 2006; Ben-Dor et al., 2010). Despite these staggering statistics, the Euro Heart Survey suggested that approximately 30% of patients suffering from severe aortic stenosis were not treated with surgical intervention (Lung et al., 2003). A significant portion of these patients are refused surgery because they are deemed to have elevated surgical risks. Considering the natural history of the pathology, patients who were refused for surgery suffer considerable morbidity and mortality. Even with maximum medical therapy, the future for these patients appeared bleak. Fortunately, the advent of transcatheter aortic valve implantation (TAVI), has led to new options for non-surgical candidates. As early as 1965, an article describing a cathetermounted valve replacement for temporary relief of aortic insufficiency in an animal (Davies H., 1965). After more than three decades of development, Cribier et al. (2002) successfully implanted a percutaneous prosthetic heart valve in a 57-year-old man. The patient, who was moribund due to numerous medical conditions, showed significant clinical and echocardiographic improvement after the valve had been implanted. Although he eventually