摘要
Background-Observed rates of restenosis after drug-eluting stenting are low(< 10%). Identification of a reliable and powerful angiographic end point will be useful in future trials. Methods and Results-Late loss(postprocedural minimum lumen diameter minus 8-month minimum lumen diameter) was measured in the angiographic cohorts of the SIRIUS(n=703)-and E-SIRIUS(n=308) trials. Two techniques, the standard normal approximation and an optimized power transformation, were used to predict binary angiographic restenosis rates and compare them with observed restenosis rates. The mean instent late loss observed in the SIRIUS trial was 0.17±0.45 mm(sirolimus) versus 1.00±0.70 mm(control). If a normal distribution was assumed, late loss accurately estimated in-stent binary angiographic restenosis for the control arm(predicted 35.4%versus observed 35.4%) but underestimated it in the sirolimus arm(predicted 0.6%versus observed 3.2%). Power transformation improved the reliability of the estimate in the sirolimus arm(predicted 3.2%[CI 1.0%to 6.7%]) with similar improvements in the E-SIRIUS trial(predicted 4.0%[CI 1.2%to 7.0%] versus observed 3.9%). In the sirolimus-eluting stent arm, in-stent late loss correlated better with target-lesion revascularization than in-segment late loss(c-statistic=0.915 versus 0.665). Conclusions-Because distributions of late loss with a low mean are right-skewed, the use of a transformation improves the accuracy of predicting low binary restenosis rates. Late loss is monotonically correlated with the probability of restenosis and yields a more efficient estimate of the restenosis process in the era of lower binary restenosis rates.
Background-Observed rates of restenosis after drug-eluting stenting are low(< 10%). Identification of a reliable and powerful angiographic end point will be useful in future trials. Methods and Results-Late loss(postprocedural minimum lumen diameter minus 8-month minimum lumen diameter) was measured in the angiographic cohorts of the SIRIUS(n=703)-and E-SIRIUS(n=308) trials. Two techniques, the standard normal approximation and an optimized power transformation, were used to predict binary angiographic restenosis rates and compare them with observed restenosis rates. The mean instent late loss observed in the SIRIUS trial was 0.17±0.45 mm(sirolimus) versus 1.00±0.70 mm(control). If a normal distribution was assumed, late loss accurately estimated in-stent binary angiographic restenosis for the control arm(predicted 35.4%versus observed 35.4%) but underestimated it in the sirolimus arm(predicted 0.6%versus observed 3.2%). Power transformation improved the reliability of the estimate in the sirolimus arm(predicted 3.2%[CI 1.0%to 6.7%]) with similar improvements in the E-SIRIUS trial(predicted 4.0%[CI 1.2%to 7.0%] versus observed 3.9%). In the sirolimus-eluting stent arm, in-stent late loss correlated better with target-lesion revascularization than in-segment late loss(c-statistic=0.915 versus 0.665). Conclusions-Because distributions of late loss with a low mean are right-skewed, the use of a transformation improves the accuracy of predicting low binary restenosis rates. Late loss is monotonically correlated with the probability of restenosis and yields a more efficient estimate of the restenosis process in the era of lower binary restenosis rates.
