Aortic stenosis (a narrowing and hardening of the heart’s aortic valve) is not uncommon among older individuals. It begins without symptoms and progresses for years but, about 50% will die within 2 years once the fitst symptoms develop. The standard approach is to surgically replace the aortic valve which will improve both heart function and survival. Unfortunately, about 30% of symptomatic individuals cannot undergo surgery because of older age, other heart problems or other medical conditions that render surgery too risky.
A new approach is called transcatheter aortic value implantation (TAVI.) In this procedure, a catheter is inserted into the large femoral artery in the groin and run up to the heart. From the catheter, the patient’s valve is opened wide with an inflatable balloon. Then a bioprosthetic value made from bovine pericardium affixed to a stainless steel support frame is deployed into place via another balloon catheter and secured to patient’s own aortic valve base.
A randomized study of 358 patients with aortic stenosis not considered surgical candidates was completed comparing TAVI to standard therapy at 21 medical centers and reported in the New England Journal of Medicine on October 21, 2010. The results were clearly favorable. Standard therapy was noted to not alter the natural history of aortic stenosis with 51% dead in one year. TAVI was superior with improved cardiac symptoms and good hemodynamic performance of the new valve which persisted for at least the first year of follow-up and with 31% dying during that year, a substantial decline in mortality.
But there is never a “free lunch” and TAVI was associated with a 5% risk of serious stroke (compared to 1% in the control group) and multiple vascular complications, the latter apparently related to the requirement for a large catheter placed into the femoral artery. Further MRI studies of patients suggest that many have new perfusion defects of the brain after TAVI suggesting that emboli from the new valve may be rather common.
But all things considered the improvement in symptoms and the reduced death rate (it took only 5 patients treated with TAVI to avoid one death by 1 year) argue that TAVI is now the appropriate therapeutic approach for those with aortic stenosis who cannot otherwise undergo surgery. Hopefully, coming improvements in the device will lead to fewer complications.
The big question – will this become the approach of choice for those who otherwise are candidates for standard surgery for aortic valve replacement?