Abstract
The astonishing, sometimes dismaying, pace with which drug-eluting stents (DES) have made the transition from their bench origins1,2 to proof of principle,3 hypothesis testing,4–6 and now routine clinical practice7 leaves even the least skeptical among us breathless. With each new advance, however, we should not lose sight of the fundamental elements of evidence-based clinical practice: “Does it work?” and “Is it safe?” It is equally astonishing and dismaying to realize the enormous investments in time, money, and sheer hard work that are required to adequately answer these deceptively simple questions. Using the RAVEL trial (Randomized Study with the Sirolimus-Coated Bx Velocity Balloon-Expandable Stent in the Treatment of Patients with de Novo Native Coronary Artery Lesions) as a model, I attempt here to outline the essentials for understanding how answers to these questions are provided, or not provided. See p 1040 As for the first element—“Does it work?”—the following questions must be addressed: What is being measured? With what is it being compared? What is the magnitude of the treatment effect? What is the relationship between time and treatment effect? In the RAVEL trial,4 the primary measure of efficacy was the angiographically assessed late lumen loss at 6 months, and a convincing case was made for the superiority of the sirolimus-eluting stent as compared with the bare metal stent (BMS). A secondary measure of efficacy (the RAVEL study was designed and powered to address the angiographic end point), target lesion revascularization (TLR) rate at 1 year, confirmed the superiority of the DES (sirolimus-eluting stent TLR rate, 0%; BMS TLR rate, 23%) with a treatment effect (ie, difference in the end points) of 23%. Intuition tells us that these 2 measures of efficacy (angiographic and clinical) should be closely correlated, but the degree of association is less …
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