But late loss is only part of the terminology in describing the outcomes of vascular interventions. For instance, the implantation of a stent-graft will first provide an acute gain in lumen diameter. In other words, there is an immediate gain in lumen size because the implanted stent opens up the vessel. However, over time, the body's inflammatory immune response (described below in the "Causes" section) reacts to the stent-graft via smooth muscle proliferation, etc., which literally pushes the stent-graft back, narrowing the vessel and "losing" at least a percentage of what was previously "gained", or late loss.