Abdominal aortic aneurysms (AAAs), or distensions of the aortic artery as it passes through abdomen, aren’t a widely talked about form of cardiovascular disease. But each year, more than 200,000 people in the U.S. are diagnosed with an AAA, and these aneurysms represent the 10th leading cause of death among men over 55.
If an aneurysm ruptures, it sets off massive internal bleeding that leaves patients with a 50/50 chance of death. Even when doctors catch AAAs early, they can only tell patients to wait until the aneurysm gets big enough to risk rupture and then have pre-emptive surgery.
“Right now, we have nothing to offer patients but watchful waiting until the problem progresses to the point that it requires surgical repair,” said Ron Dalman, PhD, chief of vascular surgery at Stanford Hospital.
There are drugs to lower the risk of many forms of cardiovascular disease, but none affect aortic aneurysms.
In a recently published paper, though, Dalman and colleagues hint that doctors may yet be able to offer medications to thwart aneurysms. The paper was the editor’s choice in the July issue of the Journal of Vascular Surgery.
The research began with two questions. Why do people with type 2 diabetes, who have a higher risk of nearly every other form of cardiovascular disease, have a lower risk of AAAs? And why do aneurysms also grow more slowly in diabetics?
“Everything else, coronary disease, peripheral arterial disease, cerebral strokes — all of it is accelerated and amplified in patients with diabetes, except for this particular cardiovascular disease,” Dalman said.
Dalman and colleagues, including visiting scholar Naoki Fujimura, MD, PhD, the first author on the paper, tapped the hospital’s electronic health record research portal, STRIDE, in hopes of getting insight into the paradox.
They identified diabetic patients with an aneurysm that had been measured at least twice, so they could track growth rates. Slower growth was most strongly linked to whether or not the patients took metformin to manage their diabetes. Metformin is the most commonly prescribed medication for type 2 diabetes.
The researchers then gave metformin to mice with AAAs to test their hypothesis. The mice that got metformin developed fewer aneurysms, and the aneurysms grew more slowly.
For early drug research, the paper is particularly promising because metformin has a long and impressive track record of safety. The drug has been used since the 1960s.
“If we could identify an effective therapeutic agent, it could prevent surgery in some patients, or delay it in others, or provide an alternative to surgery in high-risk individuals,” Dalman said, who hopes his research will double-down on advances in AAA care also pioneered at Stanford.
Cameron Scott writes about cardiovascular health at Stanford. His work has also appeared in Mother Jones, SF Weekly and the San Francisco Chronicle.