Nevertheless, we did not believe that such a design would have been feasible given the accumulating evidence from retrospective studies. Patients and their providers may have been unlikely to sign up in a trial that included a group in which patients would not receive trastuzumab. Some clinicians and investigators might have argued for a trial of trastuzumab alone versus trastuzumab plus chemotherapy, but there are limited data indicating that trastuzumab by itself is an effective strategy.19-21 Instead, we chosen a regimen of trastuzumab plus chemotherapy that might be associated with fewer toxic effects compared to the established regimens for patients with an increased risk of recurrence.The PCI procedures were performed according to the standards of treatment at each site, and only devices approved by the Drug and Food Administration were used. Study Participants We recruited individuals who were undergoing diagnostic catheterization for known or suspected coronary artery disease at hospitals without on-site cardiac surgery. To participate in MASS COMM, each medical center that didn’t have on-site cardiac medical procedures was necessary to have approval from the Massachusetts Division of Public Health and to meet minimum requirements for the amounts of PCI methods performed at the website and by the participating operators. The requirements for participation and for the amounts of PCI procedures performed at a healthcare facility and by the operators are detailed in Tables S1 and S2 in the Supplementary Appendix.