A recent study led by the Cleveland Clinic Foundation and involving colleagues from other major U.S. academic institutions sought to determine if aspirin use might be linked with the progression and clinical outcomes of AAAs.
The cohort study of 3,435 adults indicated that aspirin use was associated with slower progression of AAAs, especially in male participants and nonsmokers. “Aspirin use was not associated with all-cause mortality, major bleeding, or composite of aneurysm dissection, rupture, or repair at 10 years,” the authors reported in the Journal of the American Medical Association Network Open.
The researchers concluded that their findings “suggest that in patients with abdominal aortic aneurysm, the use of aspirin to slow aneurysm progression may be warranted.”
Preclinical studies have suggested a potential role for aspirin in slowing AAA progression and preventing rupture, according to the report, but evidence on the clinical benefit of aspirin in AAA from human studies has been lacking.
That led to the investigation of the association of aspirin use with aneurysm progression and long-term clinical outcomes in patients with AAA. Defined as the clinical outcomes were time-to-first occurrence of all-cause mortality, major bleeding, or a composite of dissection, rupture, and repair.
The retrospective, single-center cohort study involved adult patients with at least two available vascular ultrasounds at the Cleveland Clinic; excluded were patients with a history of aneurysm repair, dissection, or rupture. Participants had a mean age of 73.7 years, and most (77.5%) were male. The majority (89%) were white, with 7.4% black patients and 3.4% Asian, Hispanic, American Indian, or Pacific Islander patients. Most (63%) were verified to be taking aspirin by prescription. Follow-up continued for 10 years, and data were analyzed from May 2022 to July 2023.
The results indicated that patients taking aspirin had a slower mean (SD) annualized change in aneurysm diameter (2.8 [3.0] vs. 3.8 [4.2] mm per year; P = .001) and lower odds of having rapid aneurysm progression compared with patients not taking aspirin (adjusted odds ratio, 0.64; 95% CI, 0.49-0.89; P = .002). At 10 years, aspirin use was not associated with:
• Risk of all-cause mortality (adjusted HR [aHR], 0.92; 95% CI, 0.79-1.07; P = .32)
• Major bleeding (aHR, 0.88; 95% CI, 0.76-1.03; P = .12)
• Composite outcome (aHR, 1.16; 95% CI, 0.93-1.45; P = .09).
“In this retrospective study of a clinical cohort of 3,435 patients with objectively measured changes in aortic aneurysm growth, aspirin use was significantly associated with slower progression of AAA with a favorable safety profile,” the researchers pointed out.
Background information in the article noted that despite its substantial risk of surgical mortality, guidelines currently recommend elective AAA repair if the diameter reaches 5.5 cm for symptomatic AAA or in cases of rapidly expanding AAA.
“Currently identified risk factors for AAA development and progression include age, male sex, hypertension, and smoking, with smoking being the most impactful modifiable risk factor,” the authors wrote. “Risk factor control is currently the best available form of prevention for patients with AAA; thus, there is an unmet need for medical therapies to slow the progression of AAA. Pharmacotherapy with β-blockers, angiotensin-converting enzyme inhibitors, doxycycline, and azithromycin have all failed to show benefit in limiting AAA progression or decreasing risk of rupture.” Metformin is also being studied as a potential therapy that is associated with reduced AAA progression.
The researchers advised that preclinical studies have shown that biomechanical platelet activation in a disturbed flow environment common to AAA is a pathophysiologic mechanism driving AAA development and growth, in addition to intramural thrombus formation. Antiplatelet therapy was shown to reduce the intramural thrombi formation and aneurysm inflammatory response, decreasing the risk of rupture in animal models.
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