Original title: Short vs. Long Term Duration of Dual Antiplatelet Therapy in Patients treated for InstentRestenosis. A PRODIGY Trial substudy. Reference: Gianluca Campo el al. J Am CollCardiol, article in press.

In the study PRODIGY (Prolonging Dual Antiplatelet Treatment After Grading Stent- Induced Intimal Hyperplasia) we found that the 24 months ratio of dual antiaggregation was not more effective in reducing the composite of death, myocardial infarction or stroke, in the other hand, bleeding increased significantly compared to the 6 months ratio. Patients receiving a second procedure showing in-stent restenosis are a subgroup at particular risk of ischemic complications so the present study evaluated whether the overall results of PRODIGY are valid as well for patients with in-stent restenosis.

 The PRODIGY study randomized 1970 patients who had angioplasty and were plan to receive 6 months versus 24 months of double antiaggregation with aspirin and clopidogrel. Of these, 96 patients had restenosis at the time of inclusion and another 128 developed during the course of the study. For those that developed restenosis during the study, monitoring was restarted when the second angioplasty for another 24 months and were assigned to the same conditions as the original. The primary end point was a composite of death from any cause, nonfatal stroke or heart attack 24 months. The total population was 224 patients with in-stent restenosis, of which 114 received 6 months dual antiaggregation and 110 received 24 months. No significant differences in baseline characteristics of the two groups were observed. At the end of follow-up, 19 patients in the 6-month ratio versus 8 patients in the 24 months had shown the primary end point (p = 0.02). The estimated Kaplan-Meier events were 16.7 % for the short rate versus 7.3 % for the extended ratio (p = 0.034). Most events occurred after the first 6 months, when short ratio group had discontinued clopidogrel. Analyzing each element of the primary end point separately, lower mortality was observed in the group with 24 months of dual antiaggregation (3.5 % versus 10.5 %, P = 0.04) and a trend towards minor stroke (3% versus 8%, p = 0.07). In this sub-study in bleeding complications were similar between the two groups, unlike the overall result of PRODIGY.

Conclusion

Patients receiving a new angioplasty as a result of stent restenosis could benefit from a more prolonged administration of aspirin plus clopidogrel.

Editorial comment

The results of this in-stent restenosis sub study are opposed to the overall PRODIGY both safety and efficacy. The increased efficiency could be explained; since there is evidence that patients with in-stent restenosis have an increased risk of ischemic events. However, it is more difficult to explain why bleeding complications did not follow the same line as the main study. Since there was no formal estimate of the number of patients needed stent restenosis to show differences, these data should only be hypothesis generating. Finally, the PRODIGY study used clopidogrel so these data cannot be transferred to other antiaggregation as prasugrel or ticagrelor.

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