Absorbable Coronary Stents Show Potential

Permanent metallic coronary stents limit restenosis after angioplasty by immediately holding back intimal flaps and by preventing late vessel recoil. However, such stents may provoke an excessive healing response, which contributes to restenosis. Stents coated with antiproliferative drugs counteract intimal proliferation but are associated with delayed healing and late stent thrombosis. Therefore, the prospect of a temporary stent that works for a few months and then disappears without a trace is exciting indeed. In a manufacturer-sponsored, multicenter trial, 63 patients (mean age, 61) with single, new lesions in native coronary arteries received biodegradable magnesium stents after pre-dilatation by balloon catheter. Patients were followed up with coronary angiography and intravascular ultrasound at 4 months and with clinical assessment at 6 and 12 months.

Device and procedural success was achieved in all 63 patients; 71 stents were deployed in target lesions without acute adverse events. During the first 4 months, 24% of patients required clinically driven target-lesion revascularization (TLR), and 48% of patients developed angiographic restenosis. Ultrasound findings indicated that the restenosis was a combined effect of negative remodeling (shrinking attributed to too-rapid stent absorption) and neointimal tissue formation. By 12 months, an additional 3% of patients had required TLR, but none had experienced thrombosis or MI, and none had died.