Post-TAVI inflammatory response stronger with self-expandable vs balloon valves

The use of self-expandable valves (SEV) for transcatheter aortic valve implantation (TAVI) triggers a more robust inflammatory response relative to balloon-expandable valves (BEV), according to a recent study.

“We observed an acute increase in leukocytes and their subpopulations, and consequently, increased neutrophil-to-lymphocyte ratio (NLR) after TAVI. This response was also found to be associated with a worse 30-day outcome. SEV is associated with more leukocytosis, more lymphopaenia, and a higher NLR,” the researchers said.

A total of 348 consecutive patients (mean age 81.75±6.8 years, 57.2 percent women) who underwent TAVI for severe symptomatic aortic stenosis were included. Most (n=228) received SEVs. Baseline demographic, clinical, medication, procedural, echocardiographic, and serum characteristics were comparable between the SEV and BEV groups.

Following TAVI, there were significant and acute changes in total white blood cell (WBC) counts, as well as in the subpopulation of neutrophils, lymphocytes (p<0.0001 for all), and monocytes (p=0.004). In turn, NLR likewise showed significant acute fluctuations (p<0.0001 for all). Such changes were observed at 24 and 72 hours post-TAVI but dropped back to normal by 6 months. [PLoS One 2021;doi:10.1371/journal.pone.0258963]

Comparing between expandable device types showed that SEV was associated with a greater inflammatory response than BEV, as demonstrated by significantly higher WBC (10.442±3.859 vs 9.451±3.197 K/uL; p=0.016) and neutrophil (8.564±3.751 vs 7.552±3.068 K/uL; p=0.012) levels.

In contrast, lymphocyte counts (p=0.353) and NLR (p=0.411) were comparable between the BEV and SEV groups. These significant differences in inflammatory response also seem to have limited clinical impact. Thirty-day outcomes were all comparable between the BEV and SEV groups, including mortality (p=0.271), bleeding (p=0.786), major vascular complications (p=0.884), stroke (p=0.774), myocardial infarction (p=0.663), acute kidney injury (p=0.441), and arrhythmia (p=0.385).

Moreover, Kaplan-Meier curves showed that 10-year mortality estimates between the expandable device groups were likewise statistically similar (p=0.949).

“To the best of our knowledge, we are the first to describe a difference between the two leading TAVI valve systems that impose different mechanical stresses on the vessel wall and have different cusp origins,” the researchers said. “The underlying explanation can be ascribed to the differences in the delivery systems.”

In particular, the material that makes up the frame and leaflet components of SEV could trigger more potent inflammatory responses than those in BEV. In addition, the physical trauma induced by implantation could also contribute to such inflammatory response.

“These observations should be further pursued in larger studies as it may have a potentially detrimental effect on the long-term durability of these biological valves,” the researchers added.