Greater adverse events were associated with both low and high postprocedural aortic valve mean gradient extremes following transcatheter aortic valve implantation (TAVI) for degenerated surgical aortic valve replacement (SAVR) bioprostheses, indicating a complex and nonlinear relationship between gradients and clinical outcomes, according to a recent study published in Circulation: Cardiovascular Interventions.

Riyad Yazan Kherallah, MD, et al., included a total of 12,122 patients (median age 76 years, 91.8% White, 60.1% men) from the STS/ACC TVT Registry who underwent TAVI-in-SAVR from November 2011 to December 2019. The primary outcome was the composite of one-year all-cause mortality, stroke, myocardial infarction or valve reintervention.

Results showed that the primary outcome was most common in patients with aortic valve mean gradient ≥30 mm Hg (13.9%) and <10 mm Hg (12.1%) vs. those with ranges of 10 to 20 mm Hg (7.5%) and 20 to 30 mm Hg (6.5%; p=0.002 for all).

Higher gradients were associated with greater risk of the primary outcome as well as one-year mortality when the mean aortic valve gradient was ≥20 mm Hg (adjusted hazard ratio [HR], 1.02 per mm Hg; p<0.001 and 1.02 per mm Hg; p=0.007, respectively). However, when the mean aortic valve gradient was <20 mm Hg, higher gradients were associated with lower one-year mortality (adjusted HR, 0.98 per mm Hg; p=0.007) with no significant association with the primary composite outcome (adjusted HR, 0.99 per mm Hg; p=0.12).

Study limitations included only one year of follow-up data available through the registry, missing data that required inverse probability weighting methods, and the possibility of residual confounding. In addition, important factors such as type of transcatheter valve, transcatheter valve size, surgical valve type, surgical valve true internal diameter, the presence of preexisting patient prosthesis mismatch, and the use of balloon facture were not accounted for due to lack of data availability.

“The nonlinear relationship between echocardiographic [aortic valve] mean gradients and outcomes illustrates the limitations of using echocardiographic gradients to risk stratify patients postprocedurally…” write the authors. “Further study of factors mediating the relationship between postprocedural gradients and clinical outcomes, including low-flow states, is necessary.”

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention

Keywords: Registries, Transcatheter Aortic Valve Replacement, STS/ACC TVT Registry, National Cardiovascular Data Registries