Abstract
TAVI is now a class I indication across the whole spectrum of surgical risk groups in patients with severe symptomatic aortic stenosis. With the recent data, the indications of TAVI have been expanded to younger and lower surgical risk groups. In India, the number of TAVI procedures is increasing year by year since its first use in 2011. With a prevalence of 7.3% for isolated aortic stenosis, an estimated TAVI-eligible population is roughly about 300,000 people. 1
Lifetime management of a patient with severe aortic stenosis becomes important as this therapy is offered to younger patients with a minimum 10 to 15 years of life expectancy. The hemodynamic performance and durability of the valve are important in treating younger patients. Similarly, the rate of post-TAVI pacemaker implantation, the degree of paravalvular leak (PVL), and facilitating coronary access post-TAVI need to be optimized. To address these issues, transcatheter heart valves (THVs) have evolved greatly in terms of stent frame design, delivery catheter systems, and implantation techniques.
In this issue of the Indian Journal of Clinical Cardiology, Dr. Anoop Agarwal has extensively described the currently available THVs in India with respect to their design and anatomical subsets in which a particular valve suits best. The movement of Make in India has catapulted many Indian manufacturers into the TAVI arena. Myval from Meril Life is the most commonly used valve in India for TAVI. The features that are unique to Myval are the availability of intermediate and extra-large sizes, which allow for the treatment of a large range of annuli sizes, and a single-size large sheath for all valve sizes. The next generation of Myval Octacor shows less fore shortening during deployment due to its unique design and attaining commissural alignment with the octa align technique by crimping over a CrocoDial compass. Due to their shorter stent frame design, balloon expandable valve (BEV) can be used both retrogradely and antegradely, and by non-femoral routes as well. The recently published LANDMARK trial showed that Myval is not inferior to the Medtronic Evolut and Edwards S3 valves. 2 BEV was suitable for mitral and pulmonary valve in-valve procedures.
Hydra is the self-expanding valve by Vascular Innovations from India. The delivery system of self expandable valve (SEV) includes an inline sheath, which improves the deliverability and decreases the sheath size. To facilitate coronary access, the SEV has larger upper row cells (in Evolut, Navitor, and Hydra) and open cells (in Accurate Neo2, along with upper crowns to grasp native leaflets). The orientation of the delivery catheter for self-expanding valves in a particular clock position while introducing them at femoral artery level and orienting certain markers on the valve frame with respect to the aortic root while deploying THV can reduce commissural misalignment. For the Evolut platform, orienting the flush port of the delivery system at 3 o’clock at the femoral site and orienting the hat marker of the valve frame towards the outer curvature or central front of the aorta, and for the Accurate Neo platform, orienting the flush port of the delivery system at 12 o’clock at the femoral site and orienting one of the commissural posts (indicated by a free cell) of the valve frame towards the inner curvature or central back of the aorta can achieve commissural alignment. The depth of implantation can be guided by markers at the lower end of the valve frame in the Evolut and Hydra valves.
The author also describes the preferability of a specific valve based on the anatomy of the aortic valve, aorta, and peripheral vessels. SEV was preferred in the small annulus, TAVR in the SAVR (for better hemodynamics). BEV was preferred in patients with low coronary heights and horizontal aortas when using alternate access and in patients with a high risk of developing a complete heart block. In bicuspid valves and patients with left ventricular outflow tract (LVOT) calcium, the choice of valve has to be balanced between PVL (with SEV) and annular rupture (with BEV). In TAV cases, one should choose the size and type of valve based on coronary risk of obstruction. As most of the anatomical challenges present in a given patient, the physician should choose a valve based on a combination of these but not on a single parameter to get an optimal result with no complications.
The challenges for TAVI in India are to streamline the procedure, reduce the cost of the procedure, and address the question of long-term durability in low-risk young patients. Sahu et al. showed that 60% of TAVI patients in India are less than 60 years of age. 3 A single large center has shown that the incidence of bicuspid aortic valve stenosis is seen in 33% of the patients in India. 4 TAVI in India is performed in younger patients for symptomatic bicuspid severe aortic stenosis as compared to the USA has been our observation. There may be several reasons, including socio-economic issues, life expectancy, and cultural preferences of the patients, as to why TAVI is offered to younger patients in India. Our recommendation is that a heart team should recommend surgical aortic valve replacement as the first choice in younger bicuspid patients. That said, the 2-year results of TAVI in younger bicuspid patients in India have been comparable to the rest of the world. 5 With an aging population and increasing affordability, TAVI in India is set to become one of medicine’s greatest triumphs.