Effect of Anti-Hypertensive Medication History on Arteriovenous Fistula Maturation Outcomes

Influence of renin-angiotensin system blockades on vascular access survival in patients on maintenance hemodialysis

INTRODUCTION

Results on the association between the use of renin-angiotensin system blockades (RASBs) and vascular access-related outcomes are inconsistent. We aimed to compare vascular access-related outcomes according to the use of RASBs in hemodialysis patients.

METHODS

This study used data from a national hemodialysis quality assessment program of the Republic of Korea (n = 54,903). Group 1 was not prescribed any blood pressure-lowering drugs (n = 28,521). Group 2 was prescribed other blood pressure-lowering agents except for RASBs (n = 9571). Group 3 was prescribed RASBs (n = 16,811). Vascular access-related outcomes were classified into intervention-free survival (IFS), thrombosis-free survival (TFS), and vascular access survival (VAS).

RESULTS

No significant difference in the three access survival rates was identified among the three groups. The multivariate Cox regression analyses indicated that Group 3 had better outcomes in IFS and TFS than Group 1. The numbers of angioplasties performed were significantly greater in Group 1 than in the other two groups. The numbers of thrombectomies performed were significantly the lowest in Group 3 among all the groups.

CONCLUSIONS

Our study revealed different results according to types of access survival in univariate or multivariate analyses. The association of RASBs with favorable outcomes in vascular access remains unclear.

Effects of cardiovascular medications on primary patency of hemodialysis arteriovenous fistula

While the patency of vascular access is essential for hemodialysis patients, optimal pharmaceutical treatment to maintain arteriovenous fistula (AVF) patency remains lacking. As cardiovascular diseases are highly prevalent in patients with end-stage renal disease, various cardiovascular medications have also been used to maintain AVF patency. However, previous studies revealed inconsistent therapeutic effects and a comprehensive evaluation of this issue is needed. The present retrospective, longitudinal cohort study included patients receiving successful AVF creation. The evaluated cardiovascular medications included antiplatelet agents, antihypertensive agents, nitrates and nitrites, statins, dipyridamole, and pentoxifylline. The outcome was AVF primary patency. All laboratory data and medication profiles were recorded at baseline and followed at 3-month interval, until the end of the 2-year study period. Cox proportional regression model with time-dependent covariates was used to evaluate the risk for AVF patency loss. A total of 349 patients were included in the present study, in which 57% were men and the mean age was 65 ± 14 years. Among the included patients, 40% used antiplatelet agents, 27% used dipyridamole and 36% used statins at baseline. Of all the evaluated cardiovascular medications, only dipyridamole showed significant association with a higher risk for loss of AVF patency. To evaluate the effect of combination of antiplatelet agents and dipyridamole, the patients were classified into four groups, I: combine use of antiplatelet agents and dipyridamole, II: antiplatelet only, III: dipyridamole only; IV: none of both were used. Of the four groups, group IV exhibited highest AVF patency (52.4%), which was followed by group III (42.7%), group II (40%), and group I (28.6%), respectively. Compared with group IV, only group I showed a significantly higher risk for AVF patency loss. None of the cardiovascular medications evaluated in the present study showed a beneficial effect on AVF patency. Furthermore, dipyridamole showed an association with a higher risk of AVF patency loss. We do not suggest a beneficial effect of dipyridamole on maintaining AVF patency, particularly in combination with antiplatelet agents.

A double-blind, randomized, placebo-controlled pilot trial to evaluate safety and efficacy of vorapaxar on arteriovenous fistula maturation

BACKGROUND

Protease-activated receptor-1 antagonism by vorapaxar could facilitate arteriovenous fistula maturation but may increase bleeding risk.

OBJECTIVE

The primary objective of the Vorapaxar Study for Maturation of arteriovenous fistula for Hemodialysis Access (VorapAccess) was to determine if vorapaxar improves arteriovenous fistula functional maturation in patients with end-stage renal disease.

METHODS

VorapAccess was a randomized, placebo-controlled, double-blind pilot trial comparing 2.5 mg vorapaxar per day with placebo for twelve weeks starting on day two after arteriovenous fistula creation. The primary outcome was time to functional maturation defined as successful cannulation for six hemodialysis sessions within three weeks. The planned sample size was 50 participants. The study was terminated early after withdrawal of planned financial support. Given the small number of randomized patients, we performed descriptive analyses without inference testing.

RESULTS

A total of 13 participants were randomly allocated study drug (six vorapaxar and seven placebo). The median age was 56 years and seven participants (54%) were female. The median (minimum-maximum) days to functional maturation were 169 (77-287) days in the vorapaxar group and 145 (48-198) days in the placebo group. Six of the 13 (46%) participants had arteriovenous fistula functional maturation within 180 days; two of six (33%) in the vorapaxar group and four of seven (57%) in the placebo group. There was one bleeding event in the placebo group.

CONCLUSION

Fewer than half of participants had functional maturation within 180 days after surgery, suggesting a major need for agents or strategies that enhance arteriovenous fistula maturation.

Outcomes of initial hemodialysis vascular access in patients initiating dialysis with a tunneled catheter

BACKGROUND

Our aim was to determine factors that influence time to removal of tunneled hemodialysis catheter (THC), probability of repeat vascular access creation, and time to repeat vascular access.

METHODS

The Optum Clinformatics Data Mart claims database was queried from 2011 to 2017 for patients who initiated hemodialysis with a THC. Time from initial arteriovenous fistula (AVF)/graft (AVG) to THC removal and time to repeat AVF/AVG were analyzed using Cox proportional hazards. The likelihood of repeat AVF/AVG was analyzed using logistic regression.

RESULTS

A total of 8941 vascular access met the inclusion criteria: 6913 (77%) AVF and 2028 (23%) AVG. Median follow-up was 595 days among AVF patients (range, 1-2543 days) and 579 days among AVG patients (range, 1-2529 days). Patients undergoing AVF were younger, more likely to be male, of white race, and obese. Patients undergoing AVF were also slightly less likely to have diabetes, cardiac arrhythmia, congestive heart failure, and peripheral vascular disease than patients undergoing AVG. At 90 days and at 180 days after index access creation, significantly more patients who underwent index AVG had their THC removed compared with patients who underwent index AVF. By day 365, 78% of patients in both AVF and AVG had their THC removed. A total of 2550 (28.5%) patients underwent a repeat vascular access creation during the follow-up period: 30% of index AVF and 24% of index AVG. At 90 days, 180 days, and 365 days, significantly more patients in the index AVF group underwent a repeat vascular access creation than those in the index AVG group. Multivariate analysis demonstrated a significant interaction between vascular access type and age ≥70 years (P < .001) for time to THC removal, likelihood of repeat vascular access, and time to repeat vascular access. In the age <70 group, patients who underwent AVG were 60% more likely to have a shorter time to THC, had a 50.4% lower odds of repeat vascular access, and were 47% more likely to have a longer time to repeat vascular access compared with patients who underwent index AVF. In the age ≥70 group, patients who underwent AVG were 98% more likely to have a shorter time to THC removal, had 69.7% lower odds of repeat vascular access, and were 66% more likely to have a longer time to repeat vascular access.

CONCLUSIONS

Creation of AVG vs AVF significantly decreases the time to THC removal in dialysis-dependent patients, with a larger difference in patients aged ≥70 vs <70. Initial AVG was associated with lower odds of repeat vascular access and longer time to repeat vascular access. These results suggest that the dictum of "fistula first" is not appropriate for all patient populations and supports judicious use of AVG in achieving the more recent shift toward "catheter last."