Asthma May Raise Aortic Rupture Risk

Retail clinicians should inform patients with active asthma that they may be at greater risk for abdominal aortic aneurysm.

While it is already known that both conditions involve inflammation, experts were not previously aware of how these diseases interacted. Now, a new study published inArteriosclerosis, Thrombosis, and Vascular Biologyshows a link between airway disease and abdominal aortic aneurysm.

“Patients with [abdominal aortic aneurysm] should be aware that [their] recent asthma might increase [their] risk of aortic rupture and sudden death. It may be helpful to have more frequent monitoring,” study author Guo-Ping Shi, MSc, DSc, associate professor of medicine at Harvard Medical School and biochemist with Brigham and Women’s Hospital, toldContemporary Clinic. “Further, men over 50 with chronic asthma or other allergic diseases may have a higher risk of developing [abdominal aortic aneurysm] than those without these allergic diseases.”

To arrive at these conclusions, the researchers compared a cohort of nearly 16,000 abdominal aortic aneurysm patients from 1996 to 2012 with patients who did not have asthma.

Major study findings included:

• Patients who had hospital-diagnosed asthma within the past 12 months had a 60% greater risk of aortic rupture.
• Those who had hospital-diagnosed asthma within the past 6 months had a more than 100% greater risk of experiencing aortic rupture.
• Patients who received antiasthmatic drugs (beta-2-adrenergic receptor agonists, anticholinergic agents, inhaled glucocorticoids, or theophylline) had between a 20% to 50% greater risk of aortic rupture than those with no history of prescribed anti-asthmatic treatment.Dr. Shi noted that the risk depended on how recently the patients received the treatment.

In another cohort of men aged 65 to 74 years, those who used bronchodilators to treat asthma or reversible obstructive pulmonary disease faced a 45% greater risk of abdominal aortic aneurysm than those who had never used bronchodilators.

Even after adjusting for comorbidities, patients who were recently diagnosed with asthma had an increased risk of rupture. The researchers found evidence of potential factors such as smoking, hypertension, blood pressure, body mass index, and age being independently associated with the risk of abdominal aortic aneurysm.

Asthma and abdominal aortic aneurysm are both linked to inflammatory cell accumulation in the airway and aortic lesions. In the lungs of a patient with asthma, mast cells release cytokines, proteases, and histamine. Sputum for asthmatic patients also reveals increased neutrophil and eosinophil numbers.

“Although a direct role of eosinophils in [abdominal aortic aneurysm] remains untested, either mast cells or neutrophils promote [abdominal aortic aneurysm] development,” the researchers argued. “Mast cells contribute to [abdominal aortic aneurysm] by releasing cytokines (eg, interleukin 6 and interferon gamma) and proteases (eg, chymase and tryptase) that can activate vascular cells and breakdown the arterial extracellular matrix.”

In addition, neutrophils release proteases that may contribute to arterial wall tissue remodeling, the study authors noted.

“These shared mechanisms likely contribute to crosstalk between these diseases—a hypothesis that merits further investigation,” they concluded.

Abdominal aortic aneurysm affects between 1% and 5% of men aged 50 years or older. Aside from surgery, there are no effective preventive methods or treatments, although ultrasound could potentially be used to monitor size and growth.