Contrary to common beliefs, stainless steel may not be the most inert substance. A new study has found that stainless steel coronary stents may trigger allergic reactions to substances such as nickel, molybdenum, or chromium, which are released. These allergic reactions may be a major factor in causing in-stent restenosis.
- The researchers looked at 131 patients (avg. age 62 years) with coronary stainless-steel stents who underwent angiography for suspected restenosis. The average time since the stents were inserted was about 6 months.
- All patients underwent allergy skin tests for nickel, chromate, molybdenum, manganese, and small stainless-steel plates.
- In-stent restenosis (50% diameter stenosis) occurred in 89 patients.
- All ten patients with positive patch-test results had restenosis (4 had positive reactions to molybdenum and 7 patients had positive reactions to nickel)
The authors conclude that "Allergic reactions to nickel and molybdenum released from stents may be one of the triggering mechanisms for in-stent restenosis."
Lancet 2000; 356: 1895-1897