Chronic total coronary occlusions and the Occluded Artery Trial. A critical appraisal

The OAT trial and its angiographic substudy TOSCA-2, along with a number of published commentaries, represents examples of over-interpretation of clinical study results. A study that achieved no statistically significant result for any of the study endpoints can only claim to have proven that their null hypothesis cannot be rejected. The lack of power due to a reduction of patient numbers by one third, and an unexpected low event rate, makes it not unlikely that another trial would be able to disprove the null hypothesis. These statistical facts should be accepted by the authors and commentators. Instead, the inconclusive results were interpreted in such a way that they might apply to patient populations which had not been represented in the original trial (like CTOs without prior MI, or with viable myocardium), or for patients who could have been included, such as multivessel high risk patients, but had not been so by the investigators choice. Furthermore, major problems of the study are ignored, such as accepting TIMI 2 flow as a procedural success.