NATIONAL HARBOR, MD. – Acute kidney injury (AKI), a potentially modifiable risk factor in some cases, predicts increased mortality within the first year after transcatheter aortic valve transplantation (TAVR), according to an analysis of a U.S. registry presented at CRT 2020 sponsored by MedStar Heart & Vascular Institute.
“After adjustment, there are higher rates of all-cause mortality regardless of the severity of AKI,” reported Howard M. Julien, MD, of the University of Pennsylvania, Philadelphia.
Relative to the absence of AKI (stage 0), the hazard ratio for death at 1 year was more than threefold greater (HR, 3.26), even for those with stage 1 AKI. When unadjusted for covariates, it remained more than twice as high (HR, 2.67; P less than .001), Dr. Julien reported.
For stage 3 AKI, the unadjusted risk was more than nine times higher and remained roughly seven times greater after adjustment (HR, 7.04; P less than .001). Stage 2 AKI was linked with an adjusted risk of about the same magnitude.
Drawn from the National Cardiovascular TAVR Registry, which is maintained jointly by the Society of Thoracic Surgeons and the American College of Cardiology, data were analyzed on more than 100,000 TAVRs performed during 2012-2018. A subset of TAVRs performed between January 2016 and June 2018 served as a source of trends in what Dr. Julien described as the “modern era” of this procedure.
The incidence of AKI overall was about 10%, but rates were higher at the earliest time point in the analysis and fell modestly over the study period for all three stages. In a logistic regression analysis, the factors associated with the greatest odds ratio of developing AKI in patients following TAVR were conversion to open heart surgery (OR, 10.84, P less than .001), nonfemoral access (OR, 2.33; P less than .001), anemia (OR, 1.90; P less than .001), general versus moderate sedation (OR, 1.62; P less than .001), diabetes (OR, 1.61; P less than .001), and cardiogenic shock within 24 hours (OR, 1.60; P less than .023).
Other factors with a significant but lower relative risk association with AKI included a high contrast volume (OR, 1.004; P less than .001), use of a self-expanding valve (HR, 1.22; P = .009), severe lung disease (OR, 1.21; P = .043) and prior peripheral artery disease (HR, 1.20; P = .043).
“The message from these data is that there appears to be a cluster of patients who are unstable at the time of their procedure and are more likely to develop the most severe forms of AKI,” Dr. Julien reported.
The higher rate of AKI in patients who have diabetes is “not surprising,” but several of the factors associated with AKI are potentially modifiable. This includes choices in regard to sedation and arterial access. The value of modifying the amount of contrast is less clear, because the volume of contrast was no longer significant after an adjustment with multivariate analysis.
In fact, all of these factors require validation. Dr. Julien warned that neither the cause of AKI nor its temporal relationship to TAVR could be consistently determined from the registry data. In addition, retrospective analyses always include the potential for unrecognized residual confounders.
Still, these data are useful for drawing attention to the fact that AKI is a common complication of TAVR and one that is associated with adverse outcomes, including reduced survival at 1 year.
“The factors taken from these data might be useful to help identify patients who are at risk of the most severe forms of AKI and, hopefully, lead to prevention strategies that take these characteristics into consideration,” Dr. Julien said.
Dr. Julien reported no potential financial conflicts of interest.