Aortic valve replacement in patients aged 50 to 69 years: Analysis using Korean National Big Data

Abstract Background The aim of this study was to compare the clinical outcomes and long‐term survival in patients who underwent isolated aortic valve replacement (AVR) with mechanical versus bioprosthetic valves. Methods Patients aged 50–69 years who had undergone AVR from 2002 to 2018 were identified and their characteristics were collected from Korean National Health Information Database formed by the National Health Insurance Service, Republic of Korea. Of the 5792 patients, 1060 patients were excluded due to missing values on characteristics. Of the 4732 study patients, 1945 patients (41.1%) had received bioprosthetic valves (Group B) and 2787 patients (58.9%) had received mechanical valves (Group M). A propensity score‐matched analysis was performed to match 1429 patients in each group. Data on mortality, cardiac mortality, reoperations, cerebrovascular accidents, and bleeding complications were obtained. Results The overall survival rates at 5 and 10 years postoperatively were 87.8% and 75.2% in the matched Group B and 91.2% and 76.7% in the matched Group M, respectively (p = .140). Freedom from cardiac death rates at postoperative 5 and 10 years were 95.6% and 92.4% in the matched Group B and 96.0% and 92.1% in the matched Group M, respectively (p = .540). The cumulative incidence of reoperation was higher in the matched Group B than in the matched Group M (p = .007), and the cumulative incidence of major bleeding was higher in the matched Group M than in the matched Group B (p = .039). Conclusion In patients aged 50–69 years who underwent isolated AVR, the patients who received bioprosthetic valves showed similar cardiac mortality‐free survival and long‐term survival rates to the patients who received mechanical valves.


Aortic valve replacement ([AV]R) is the standard treatment in patients
with severe AV disease, and has shown improvement of survival, quality of life, and left ventricular (LV) function. [1][2][3] The choice of a valve prosthesis used in AVR is a complex and individualized decision which is based on valve-related factors such as valve durability, hemodynamics and reintervention risks, and patient factors, such as lifestyle, preferences, life expectancy, and adherence to medication. 4,5 Of the various factors in making decision of the type of a valve prosthesis, patient's age is one of the most important factors.
Current AVR guidelines from the American Heart Association/ American College of Cardiology states that it is reasonable to choose mechanical prosthesis in patients <50 years of age and biological prosthesis in patients >65 years of age. Either type of prosthesis is considered reasonable in patients 50-65 years of age by individualizing the patient's status and condition. 6 As for the European Society of Cardiology/European Association for Cardio-Thoracic Surgery AVR guidelines, mechanical prosthesis should be considered in patients <60 years of age and biological prosthesis in patients >65 years of age. In patients 60-65 years of age, both types of prosthesis are considered acceptable. 7 Previous studies have compared the long-term survival and clinical outcomes after AVR with mechanical versus bioprosthetic valves in these "middle-aged" patients. [8][9][10][11][12][13][14] Conflicting results, however, have been reported on clinical outcomes and long-term survival.
The aim of the present study was to compare the clinical outcomes and long-term survival in patients who underwent isolated AVR with mechanical versus bioprosthetic valves by analyzing the Korean national big data. cancer, and more aortic regurgitation. After matching, however, there were no differences in demographic data between the matched groups. After matching, all covariates were well balanced between the groups with standardized mean difference ≤10% ( Figure 1 and Table 1). Data on reoperations (redo-AVR), cerebrovascular accidents, and major bleeding complications during the follow-up were collected by using National Health Information Database. Thirty-day mortalities was defined as any death within 30 days of procedure, including deaths after hospital discharge. Cerebrovascular accidents

| Statistical analysis
Statistical analysis was performed with R software, version 3.6.0 (R Foundation for Statistical Computing, Vienna, Austria). Continuous data were expressed as the mean ± standard deviation for normally distributed variables or as medians (interquartile range) for non-normally distributed variables according to the Shapiro-Wilk test, and categoric data were expressed as count (percentage). Comparison between continuous variables were made using the Student t test, and categoric variables were made T A B L E 1 Comparison of Groups B and M before and after propensity score-matching 3 | RESULTS

| Trend in selection of the prostheses
In the 2002, over 80% of isolated AVR was performed using mechanical prostheses in patients aged 50-69 years old. However, the difference between the bioprosthetic and mechanical valves decreased after 2005. In the year of 2017 and 2018, the patients who received AVR using mechanical valves outnumbered the patients who received AVR using bioprosthetic valves (Figure 2).

| Cumulative incidence of reoperation, stroke, and major bleeding
There were 15 reoperations in all population during the study period.
After the propensity score matching, there were 6 reoperations (  p < .001) to be significant predictors of all-cause mortality, and these variables were also statistically significant predictors by multivariable analysis (Table 2B).

| COMMENT
This nationwide, propensity score-matched study compared long-  AVR with mechanical valves compared to those with bioprosthetic valves. 8,[10][11][12][17][18][19] In the present study, there were no differences between the two groups in survival as well as cardiac mortality-free survival. No significant differences were found in overall survival as well as cardiac mortality-free survival between patients who underwent AVR with biological prosthesis and mechanical prosthesis in the present study. The result of the study may have more statistical significance since the study was conducted by using the National big data, and propensity score matching was performed.
Necessity of reoperation and risk of bleeding are major strengths and weaknesses of the two different types of prosthetic valves.
Other studies have revealed mechanical valves to be superior than biological prostheses in terms of reoperation [8][9][10][11][12][13]15,16,18,20 and biological prostheses to be superior in terms of bleeding. 9,11,13,16,20 In the present study, similarly, reoperation was more frequent in patients who underwent AVR with biological prosthesis, and major bleeding event more frequent in patients who underwent AVR with mechanical prosthesis. However, we are careful to draw a conclusion on reoperations because the absolute events were too small and the follow-up period of this study was relatively short compared to the currently known longevity of bioprosthetic valves. Further information after 15 years of follow-up is warranted.
Although the necessity of reoperation and risk of bleeding are the major points that are regarded in selecting the type of prosthesis used in AVR, no significant difference in the survival makes the decision more freely or patient-tailored in selecting the type of prosthesis in patients aged 50-69 years who is undergoing isolated AVR. Abbreviations: CI, confidence interval; HR, hazard ratio.