Stephen J.LurieMD, PhD, Senior EditorIndividualAuthorJody W.ZylkeMD, Contributing EditorIndividualAuthor
To the Editor: Dr Magid and colleagues1 found lower mortality rates in patients with acute myocardial infarction treated with primary angioplasty than those treated with thrombolysis at hospitals with high or intermediate volumes of primary angioplasty.
However, 2 points require closer examination. The first is the lack of data on hospital length of stay. Since the end point was in-hospital mortality, the procedure with earlier discharge (usually primary angioplasty) clearly has the advantage of reducing the time for detecting in-hospital events. The second point is the timing of thrombolysis. It is well known that for each hour of delay, the absolute risk reduction for death decreases by 0.16%.2 This source of possible confounding could be addressed by comparing the outcomes of patients who were admitted within 1 and 2 hours of symptom onset and received thrombolysis.
Mariotto A. Outcomes of Angioplasty vs Thrombolysis by Hospital Angioplasty Volume. JAMA. 2001;285(13):1701-1702. doi:10.1001/jama.285.13.1701