Applying intravascular ultrasound to optimize the placement of coronary drug-eluting stents

Intravascular ultrasound (IVUS) has provided in the last 2 decades major insights into the pathophysiology of coronary artery disease, and the mechanisms of action of percutaneous revascularization devices, helping the widespread adoption of coronary stents. The introduction of drug-eluting stents (DES) has recently lead to a revolution in the field of interventional cardiology, by virtually eliminating restenosis in selected low-risk lesions and significantly reducing both restenosis and repeat revascularizations in higher risk lesions. At the moment, the role of IVUS in the DES era is not well defined. Clinical studies utilizing IVUS in DES implantation used this technology mainly to evaluate the endpoint of intimal hyperplasia and to study the problem of incomplete apposition. On a theoretical basis, a method able to better evaluate optimal placement of a local drug delivery system should have a high rationale. Despite this sound preamble, no specific investigation has been conducted to evaluate the clinical need and possible advantage of routine IVUS for DES implantation and uncertainty is still present. A major hindrance lays in the low incidence of restenosis in most randomized trials enrolling few selected lesions per patient, as this fact enlarges the number of patients who need to be treated to demonstrate a benefit and casts doubts on the cost effectiveness of a more expensive and time consuming approach. The situation is bound to change when more complex patients and lesions are being treated, a setting associated with a higher event rate even when DES are used. While waiting for a prospective study addressing such issue, we can only rely on indirect evidence to justify and support the usage of IVUS in complex clinical settings with implantation of DES.