International Circulation: How would you evaluate the value of platelet function testing in the prediction of thrombosis risk and decision of DAPT duration?
　　Dr. Kaul: Platelet function testing (PFT) has modest prognostic ability (ability to predict risk regardless of treatment allocation) but no proven predictive utility (ability to modify risk by therapeutic targeting) as PFT-guided intensification of antiplatelet therapy has failed to demonstrate a treatment benefit.  In my opinion， PFT remains an investigational tool and not ready for prime time clinical practice.
　　International Circulation: It has been reported that genetic polymorphism testing is valuable for the prognosis of genetic individual therapy. Is it necessary to have this for individual DAPT?
　　Dr. Kaul: The prognostic as well predictive utility of genotype testing is even lower compared with PFT. In addition， the low prognostic utility is further compounded by the very low frequency of adverse ischemic events such as stent thrombosis. Thus， when the pretest probability (prevalence) is very low， post-test probability (positive predictive value) is not going to be very high， thereby limiting the clinical utility of both PFT and genotype testing.
　　While genotype is strongly associated with stent thrombosis risk， the discriminating ability is modest and the predictive utility for therapeutic modification of risk remains unproven. Guideline recommendations for use of genotyping are based more on consensus opinion rather than empirical evidence.
　　《国际循环》：你如何评价血小板功能检测在预测血栓形成风险和决策双联抗血小板治疗时间上的价值？
　　Kaul教授：血小板功能检测具有中度的判断预后的能力（即无论分配何种治疗都可以判断预后），但是未被证实具有预测效力（即通过治疗干预该指标可以降低患者风险），因为基于血小板功能检测的强化抗血小板治疗未被证实能够给患者带来治疗益处。在我看来，心血管功能检测当前还是一个研究工具，还不适合在临床实践中应用。
　　《国际循环》：有研究报道，基因多态性检测对于基于遗传学的个体化治疗的预后判断是有价值的。每个接受双联抗血小板治疗的患者是否有必要接受遗传多态性检测？
　　Kaul教授：基因型检测的预后判断价值和预测价值甚至比血小板功能检测还要低。另外，基因型检测较低的预后价值被支架血栓等不良缺血事件发生率非常低进一步复杂化了。因此，检测前可能性（患病率）非常低的情况下，检测后的可能性（阳性预测值）不会非常高，因此限制了血小板功能检测和基因型检测的临床应用。
　　当基因型与支架血栓风险具有强相关关系时，基因型的鉴别力为中等，治疗干预风险的预测能力仍未得到证实。当前指南对基因型检测的推荐更多地是基于共识意见，而不是经验性证据。
　　International Circulation: The duration of DAPT after PCI is still recommended as 12 months by current guidelines. However it has been questioned as some trials confirmed that longer-term treatment may have more benefits while some trials showed no difference between 6 month and 12 month. What are your thoughts on length of treatment?
　　Dr. Kaul: The current evidence base is insufficient to adjudicate the optimal duration of DAPT post-PCI. Most trials that have been performed to address this question are limited by small sample size， lack of rigorous statistical methodology， and lack of ability to address heterogeneity of treatment effect across patient risk， complexity of intervention or stent type categories. Several large methodologically rigorous trials are currently under way that will hopefully provide valid data to reliably guide clinical practice in the near future. Until then， I would recommend a prudent approach of tailoring duration of DAPT to the underlying patient risk， complexity of intervention and the type of DES. For high-risk patients (such as those with diabetes， ACS) undergoing complex PCI (left main disease， multivessel disease， bifurcation lesions)， I would recommend treatment duration longer than 6-12m. For elective noncomplex PCIs with newer generation DES， I might feel comfortable with 3-6months of DAPT.
　　《国际循环》：当前指南仍然推荐PCI后的双联抗血小板治疗时间为12个月。但是，这一推荐受到一些质疑，因为一些研究证实双联抗血小板治疗时间更长可能带来更多的益处，而另一些研究则显示6个月和12个月双联抗血小板治疗的获益没有差异。您怎么看双联抗血小板治疗时间的问题？
　　Kaul教授：当前的证据还不足以让我们确定PCI术后双联抗血小板治疗的最佳治疗时间。大多数尝试回答最佳治疗时间的临床试验意义有限，因为样本量过小、缺乏严格的统计学方法和无法确定患者风险、介入操作复杂程度或支架类型所导致的治疗效应的异质性。几项样本量较大的、采用了严格方法学的研究目前正在进行当中，期望这些研究能够提供有效的数据来可靠地指导不远的未来的临床实践。到那个时候，我们会推荐采取一种审慎的治疗方案，即根据患者潜在的风险、介入治疗的复杂程度和药物洗脱支架的类型个体化地确定双联抗血小板治疗的时间。对于接受了复杂PCI手术（左主干病变、多支病变和分叉病变）的高危患者（例如合并糖尿病或急性冠状动脉综合征），会推荐6～12个月以上的双联抗血小板治疗。对于置入了更新一代药物洗脱支架的非复杂病变择期PCI的患者，我觉得3～6个月的双联抗血小板治疗就足够了。