Association of Statin and Antiplatelet Use with Survival in Patients with AAA with and without Concomitant Atherosclerotic Occlusive Disease

Abstract

Statin therapy has been associated with improved clinical outcomes in patients undergoing treatment for vascular disease. Current guidelines do not address statin therapy in isolated abdominal aortic aneurysm (AAA) in the absence of other atherosclerotic cardiovascular disease (ASCVD). This study aims to elucidate effects of statin therapy, either as monotherapy or combined with antiplatelet agents, on the long-term mortality of patients with and without ASCVD who undergo elective AAA repair. A retrospective review was performed on all AAA patients treated electively with endovascular (EVAR) and open aortic repair (OAR) in the Society for Vascular Surgery Vascular Quality Initiative from 2003-2020. Long-term mortality was evaluated based on the presence of statin and antiplatelet medication use at discharge stratified by those with and without a history of ASCVD. Unadjusted survival was estimated by Kaplan Meier methodology. Cox proportional hazards modeling was used to determine mortality risk after adjusting for key factors. A total of 47,012 AAA repairs were selected for analysis: 80.7% EVAR (N=40,153) and 19.3% OAR (N=6,859). EVAR patients on combined statin/antiplatelet (AP) therapy had significantly better survival irrespective of whether they had known ASCVD. In the presence of ASCVD, EVAR patients on statin alone had improved survival compared to those not on a statin (10.9 ± 0.5 vs. 10.5 ± 0.4 years, Log Rank < 0.001), with survival being even greater among those receiving combined statin/AP therapy (12.2 ± 0.2 vs. 10.5 ± 0.4 years, Log Rank < 0.001). In the absence of ASCVD, EVAR patients on statin alone also had better mean survival compared to patients not on a statin (8.7 ± 0.5 vs. 8.4 ± 0.4 years, Log Rank<.001), with higher survival among statin/AP therapy patients (9.4 ± 0.2 years vs. 8.7 ± 0.5 years, Log Rank < 0.001). Comparison of adjusted survival via Cox multivariable regression demonstrated a protective effect of statins (HR=0.737, P=0.04, vs. no medication) and combined statin/AP therapy (HR=0.659, P=0.001, vs no medication) in patients with ASCVD history. A similar protective effect (statin: HR 0.826, P=0.05. Combination statin/AP: HR 0.726, P < 0.001, vs. no medication) was identified in patients without ASCVD history. Within the OAR cohort, statin therapy was not associated with improved survival among patients without ASCVD; however, combined statin/AP therapy had a protective effect for patients with a known ASCVD diagnosis. Based on KM analysis, OAR patients with ASCVD on combined statin/AP therapy had significantly higher mean survival compared to isolated statin therapy (12.7 ± 0.2 vs. 10.3 ± 0.65 years) and no medical therapy (10.5 ± 0.8 years, Log Rank < 0.001). In KM analysis, OAR patients without known ASCVD indications (N=3591) had no significant survival differences based on the presence of combined statin/AP therapy (8.4 ± .07 vs. 8.5 ± .11 years, Log Rank=0 638). Isolated statin therapy and combined statin/AP therapy showed significant survival benefit in all EVAR and OAR patients with ASCVD indications, as well as among EVAR patients without a known ASCVD diagnosis. OAR patients without ASCVD did not have a significant survival benefit from statin therapy, but low numbers in this group may have confounded the findings. Combined statin/AP therapy appears to have significant post-repair survival benefits even in isolated AAA without ASCVD, as demonstrated in post-EVAR patients in this study. Expansion of statin use recommendations within aneurysm treatment guidelines may be warranted.