Limitations
The randomized participants in this trial were included because the cardiologist believed coronary instrumentation with the pressure wire was feasible, but this decision is subjective and some patients may not have been included due to operator preference. Even though some features of severe coronary disease were exclusion criteria (e.g. a severely calcified coronary artery), some patients with severe coronary disease were still included supporting generalizability of the trial findings. For example, 6.6% of the participants were referred for CABG; 19% of the participants underwent angiography five or more days from the index episode of myocardial ischaemia. This time interval is explained by clinical service pressures that delayed access to the catheter laboratory in some of the hospitals in this trial.
Most of the participants in our trial received clopidogrel whereas ticagrelor, which improves cardiovascular outcomes in ACS patients compared with clopidogrel, is now recommended in NSTEMI patients. We have reported the cardiologists' visual interpretation of the angiogram as actually performed in the study participants. A quantitative coronary analysis by blinded observers is currently on-going.
Our study was designed (but not powered) to assess between-group differences in health outcomes. There are too few cardiac events to draw firm conclusions and the prognostic significance of FFR-guided management in patients with optimal dual anti-platelet therapy should be further assessed in a larger trial with longer-term follow-up.