NEJM: Do TAVI complications outweigh the benefits?
At ACC.11 in New Orleans, Craig R. Smith, MD, co-principal investigator of the PARTNER trial and chief of the division of cardiothoracic surgery at New York-Presbyterian Hospital/Columbia University Medical Center in New York City, summarized the trial’s findings, which showed that TAVI can improve one-year survival in high-risk patients who are not eligible for surgery.
In the PARTNER A trial, 349 patients were randomized to receive TAVI and 350 patients were randomized to receive aortic valve replacement. Within the transcatheter group, 244 patients were assigned to transfemoral placement and 104 were randomized to transapical placement. While the researchers noted that TAVI improved patients’ quality of life, decreased hospitalizations for aortic stenosis at one-year and improved survival, they also found that patients in tranasapical-placement group had increased rates of CABG, cerebrovascular disease and peripheral vascular disease.
Hartzell V. Schaff, MD, of the Mayo Clinic in Rochester, Minn., expressed reservations about the potential vascular and technical complications connected to the approach, which he published in an accompanying editorial in the latest issue of NEJM. In fact, he wrote that the “avoidance of a sternotomy by transfemoral of transapical aortic-valve implantation appears to come at the price” of some serious complications including an increased risk of embolic stroke and paravalvular leakage.
However, Schaff noted these issues could be remedied by increased operator experience and device refinement. In fact, Schaff said that smaller, more flexible delivery systems should be developed because they could both increase the number of patients eligible for transfemoral insertion and decrease vascular injury.
Smith and colleagues outlined the risk of stroke and transient ischemic attack (TIA) in the TAVI arm within the PARTNER A results. Patients had a 5.5 percent risk of stroke or TIA 30 days post-TAVI. This rate increased to 8.3 percent by one-year. These rates for patients undergoing the surgical approach were nearly half and were 2.4 percent and 4.3 percent, respectively. Schaff called these high rates a “special concern,” and asked how a procedure like TAVI, with neurologic complication rates that were twice of the surgical technique, became so widely adopted.
"What are the mechanisms of stroke and how might these be mitigated?” he asked. These neurologic complications with TAVI vary from zero to 11 percent within single centers and data registries. However, that risk of stroke and TIA in PARTNER are comparable to previous data. Therefore, Schaff noted that “the one-in-20 occurrence of stroke or transient ischemic attack after transcatheter replacement might be considered a complication that comes with the territory in treating elderly patients with multiple coexisting conditions.”
Additionally, Schaff said that the high rates of neurological complications may be reasonable for this specific population of patients who are unable to undergo surgical replacement. However, he noted that “the [PARTNER] findings present a dilemma in balancing the risks of increased neurologic complications against the benefits of avoiding sternotomy and cardiopulmonary bypass.”
Schaff advised that patients enrolled in PARTNER A trial should be evaluated to determine “the durability of the transcatheter prosthesis and to assess the risk of late thromboembolic events.” He offered that inserting prosthesis without removing the diseased valve could predispose thrombus formation.
“Technological refinement of transcatheter valves and adjunctive procedures, such as the use of embolic protection devices, will facilitate transcatheter replacement and may improve outcomes, but these new devices should be evaluated in controlled trials with randomization against current standard techniques,” Schaff concluded.
Smith et al noted that the high number of neurological events occurring in the PARTNER A study was a “concern,” and said that the majority of strokes were procedure-related and embolic. And despite this heightened risk of stroke for the TAVI group, the authors noted that the composite rates of death at 30 days and one-year were similar.
“Future studies will determine whether delivery systems with smaller diameters, procedural changes, or embolic-protection devices can reduce the incidence of stroke after transcatheter replacement,” Smith et al concluded. Additionally, they pushed for RCTs that would look at the TAVI approach in lower-risk aortic stenosis patients.
Results of the PARTNER A trial were also published online June 5 issue in the NEJM.