Need to clarify Thrombolysis In Myocardial Ischemia (TIMI) scale scoring method in the Penumbra Pivotal Stroke Trial.

Stroke welcomes Letters to the Editor and will publish them, if suitable, as space permits. They should not exceed 750 words (including references) and may be subject to editing or abridgment. Please submit letters in duplicate, typed double-spaced. Include a fax number for the corresponding author and a completed copyright transfer agreement form (available online at To the Editor: We congratulate the Penumbra Investigators on the successful completion of the Penumbra Pivotal Stroke Trial. 1 The addition of the Penumbra System to the therapeutic armamentarium is an important advance in acute stroke care. A major defect of the report is the investigators do not specify how they measured the primary trial outcome, angiographic revascularization. They state without further elaboration that the core laboratory used the Thrombolysis In Myocardial Ischemia (TIMI) scale to assess revascularization. However, the TIMI scale was developed for the myocardial circulation and cannot be applied in the more complex cervicocephalic arterial tree without the creation of additional operational rules. A recent review found no fewer than 7 different operationalized versions of the TIMI scale being used across different stroke trials. 2 The Stroke Therapy Academic Industry Roundtable (STAIR) has for this reason recommended abandonment of the TIMI in future cere-bral revascularization clinical trials and use of one or more of the more transparent and uniformly applicable scales that have been developed for the brain. 3 For past studies that did use the TIMI, like the Penumbra Pivotal Trial, it is absolutely essential that the idiosyncratic rules used by the trial core laboratory to apply the TIMI to the brain circulation be specified in full, as was done in the reporting of the Mechanical Embolus Removal in Cerebral Ischemia (MERCI), Multi-MERCI, and Interventional Management of Stroke IMS 1 and 2 trials. 4 – 6 It is difficult to determine whether the reported higher recan-alization rate in the Penumbra Trial compared with the MERCI, Multi-MERCI, IMS 1, and IMS 2 trials is an artifact of different angiographic scoring methods or a genuine difference in device technical efficacy. The similar clinical outcomes of the Penum-bra patients and the MERCI/Multi-MERCI patients suggest that, when scored with the same method, the actual revascularization rates likely were similar. To complete their trial report, the Penumbra trialists should provide a full specification of how they applied the TIMI scale to their cerebral angiograms. If the scoring method did indeed differ in the Penumbra trial …