Response to Letter Regarding Article, “Correlates and Long-Term Outcomes of Angiographically Proven Stent Thrombosis with Sirolimus- and Paclitaxel-Eluting Stents”
We appreciate the letter and comments of Dr Tsai et al regarding correlates of drug-eluting stent (DES) thrombosis. We agree, as stated in our article, that cessation of clopidogrel is not the sole correlate for stent thrombosis.1 We identified chronic renal failure, insulin-treated diabetes, bifurcation lesions, and others as correlates. It is possible that there are other mechanical and biological correlates such as stent malapposition, lack of stent expansion, and resistance to antiplatelet therapy. Clearly, we are experiencing higher rates of thrombosis in DES when compared with metallic stents, and this phenomenon is also seen in patients who are on dual antiplatelet therapy. The rates of healing and reendothelialization seem to vary among patients and drugs, as documented from autopsies and angioscopy studies performed on patients who underwent DES implantation. Some lack healing at 2 years, whereas others reported complete endothelialization at 3 months. The suggestion of clopidogrel resistance is intriguing but not well defined and not yet proven as a correlate in this population. Interestingly, the indications for use of clopidogrel are 3 months for sirolimus- and 6 months for paclitaxel-eluting stents. The observations of late thrombosis seen from 9 to 48 months after implantation are reported more in patients with DES than in those with metallic stents. Whereas the overall reported compliance with clopidogrel is poor throughout the world because of the prohibitive costs and the high rate of side effects such as bleeding, aspirin may play a major role in prevention of stent thrombosis. We reported on a series of subjects who were on aspirin alone at least 1 year after stent implantation and experienced stent thrombosis immediately after cessation of aspirin. Although the utility of testing all patients who receive DES for clopidogrel resistance is not practical and not yet proven, it may be helpful to test for aspirin resistance in those patients who stopped taking clopidogrel and to emphasize the necessity of continuation of aspirin for several years until we learn more about other correlates of stent thrombosis or solve the problem of stent thrombosis with a safer DES.
Kuchulakanti PK, Chu WW, Torguson R, Ohlmann P, Rha SW, Clavijo LC, Kim SW, Bui A, Gevorkian N, Xue Z, Smith K, Fournadjieva J, Suddath WO, Satler LF, Pichard AD, Kent KM, Waksman R. Correlates and long-term outcomes of angiographically proven stent thrombosis with sirolimus- and paclitaxel-eluting stents. Circulation. 2006; 113: 1108–1113.