Relationship of Symptom-Onset-to-Balloon Time and Door-to-Balloon Time With Mortality in Patients Undergoing Angioplasty for Acute Myocardial Infarction

Abstract

In the treatment of acute myocardial infarction (MI), rapid time to treatment with thrombolytic therapy and rapid achievement of reperfusion of the infarct-related artery with thrombolytic therapy (the "open artery theory") is beneficial.^1-5 Angiographic studies have supported the link between higher 90-minute (but not 180-minute) infarct-related artery patency and improved survival,^4,6 suggesting that small differences in time to achieving reperfusion make clinically important differences in mortality. Primary (or "direct") angioplasty has been found to be a useful means of achieving reperfusion in acute ST-elevation MI compared with thrombolytic therapy in randomized clinical trials.^7-10 However, no mortality benefit of primary angioplasty over thrombolysis was observed in several registries in which the delays in performing primary angioplasty were longer.^11-14 In these studies, the time between hospital arrival and performance of the primary angioplasty, the so-called door-to-balloon time,⁵ was on average between 2 and 3 hours,^11-14 much longer than in the initial clinical trials.^7,8 We hypothesized that, in accord with experimental¹⁵ and clinical studies,^1-5 the more rapidly reperfusion is achieved with primary angioplasty the better the survival, and conversely, that delays in achieving reperfusion would result in higher mortality. Because prior studies of primary angioplasty have involved only 200⁷ to 1300^16-18 patients, it has not been possible to assess reliably the effect of time delays on mortality. We prospectively tested this hypothesis in the Second National Registry of Myocardial Infarction (NRMI-2), which included more than 27,000 patients treated with primary angioplasty. (A list of NRMI-2 investigators and sites is available from the data coordinating center: Ovation Research Group, Highland Park, Ill.)