Oxidation-Reduction Potential in Patients undergoing Transcatheter or Surgical Aortic Valve Replacement

Abstract

Background: Aortic valve stenosis has gained increasingly more importance due to its high prevalence in elderly people. More than two decades ago, transcatheter aortic valve replacement emerged for patients who were denied surgery, and its noninferiority has been demonstrated in numerous studies. Oxidative stress has generated great interest because of its sensitivity to cell damage and the possibility of offering early hints of clinical outcomes. The aim of the present study was to investigate whether there is a significant difference between transcatheter (TAVR) or surgical aortic valve replacement (SAVR) in terms of the changes in oxidation-reduction potential (ORP) and antioxidant capacity. Therefore, we investigated perioperative oxidative stress levels and their influence on clinical outcomes.

Methods: A total of 72 patients (50% TAVR versus 50% SAVR) were included in the present study. Static oxidation-reduction potential (sORP) and antioxidant capacity were measured using the RedoxSys™ Diagnostic System (Luoxis Diagnostics, USA) in serum samples drawn before and after surgery, as well as on the first postoperative day. In addition, clinical data were obtained to evaluate the clinical outcome of each case.

Results: TAVR patients had higher preoperative sORP levels compared to the SAVR patients and more severe comorbidities. Unlike the TAVR cohort, patients in the SAVR group showed a significant difference in sORP from the pre- to postoperative levels. Capacity demonstrated higher preoperative levels in the SAVR cohort and also a greater difference postoperatively compared to the TAVR cohort. Regression analysis revealed a significant correlation between pre- and postoperative capacity levels (r = -0.9931, p < 0.0001), providing a method of predicting postoperative capacity levels by knowing the preoperative levels. According to the multivariable analysis, both sORP and antioxidant capacity are dependent on time point, baseline value, and type of surgery, with the largest variations observed for time effect and surgery method.

Conclusion: A high preoperative sORP level correlated to more severe illness in the TAVR patients. As the TAVR patients did not show significant differences in their preoperative levels, we assume that there was a smaller production of oxidative agents during TAVR due to the less invasive nature of the procedure. Baseline values and development of antioxidant capacity values strengthen this hypothesis. The significant correlation of pre- and postoperative capacity levels might allow high risk patients to be detected more easily and might provide more adequate and individualized therapy preoperatively. This trial is registered with clinicaltrials.gov, identifier: NCT 02488876.

Figure 1

A STROBE flowchart demonstrating patient recruitment.

Figure 2

Boxplot of sORP in mV at all time points (categorical presentation is on the x-axis: T1, T2, and T3), categorized by surgery methods (SAVR versus TAVR). Note that the baseline sORP in the TAVR cohort is significantly higher compared to that of the SAVR group.

Figure 3

Boxplot of sORP differences at T2 compared with T3 and baseline T1 (i.e., T2-T1, T3-T1), in mV (the categorical presentation is on the x-axis), stratified by the surgery method (SAVR versus TAVR). The reference line at 0 indicates the increase or decrease in contrast to baseline (T1).

Figure 4

A boxplot of the antioxidant capacity in µC at all investigated time points (the categorical presentation is on the x-axis: T1, T2, and T3) stratified by surgery method (SAVR versus TAVR) and truncated at 1.0 µC for better illustration of the data distribution. Only 6 capacity measurements were observed above 1.0 µC: 2 measurements in the SAVR group with values < 2.0 µC each at T1 and T2; 2 measurements in TAVR: 2.72 µC at T1 and 3.37 µC at T2.

Figure 5

A boxplot of sORP in mV at all time points (categorical presentation on x-axis: T1, T2, and T3) stratified by sex (male versus female).

Figure 6

A boxplot of sORP in mV at all time points (the categorical presentation is on the x-axis: T1, T2, and T3), stratified by the status of acute kidney injury (AKI) at the corresponding time point.