Background: Clinical outcomes after stent placement in patients with a history of metal allergy remain incompletely understood. We performed a single-center retrospective study to evaluate such outcomes.
Methods and results: Twenty-nine allergic patients who underwent coronary stent implantation were compared with a nonallergic group (n=250) matched for demographics and a propensity score for allergy to metal. Hypersensitivity to nickel was reported in 26 of 29 and chromium in 9 of 29. Patch testing performed in 11 of 29 patients was positive in all. Comparing allergy versus control subjects, there were no differences in number of segments treated (1.4±0.7 versus 1.5±0.7), stents placed (1.7±1.1 versus 1.6±0.9), and frequency of drug-eluting stent usage (52% versus 60%). In-hospital death (0% versus 0%), myocardial infarction (MI, 4% versus 3%, P=0.27), and 30-day death (3% versus 0%, P=0.53) and MI (3% versus 4%, P=0.71) were statistically similar. There were no differences in 4-year death (12% versus 13%), target lesion revascularization (TLR, 13 versus 17%, P=0.54), or death/MI/TLR (24% versus 34%, P=0.20). Clinically driven repeat angiography in 12 of 29 allergy patients revealed binary restenosis rates of 27% in bare metal stents and 0% in drug-eluting stents, with mean diameter in-stent restenosis of 36% and 8%, respectively. There was no change in circulating eosinophil and lymphocyte counts after stenting in the allergy group (0.19-0.20, P=0.67, and 1.90-1.79, P=0.59, respectively).
Conclusions: A history of metal allergy was not associated with adverse early or late outcomes in this single-center study.