Background Current guidelines support primary percutaneous coronary intervention (primary PCI) as the first treatment of choice (as opposed to thrombolytic therapy) for patients with acute ST-segment elevation myocardial infarction (STEMI) especially when delivered within 12 hours of symptom onset. We aimed to evaluate the impact of different clinical pathways on reduction of reperfusion delay and subsequent improvement in outcomes in patients with STEMI.Methods From November 2005 to November 2007, 546 consecutive patients with definite STEMI, who upon arrival at the emergency room were triaged to undergo primary PCI, were included. Of them, 271 patients were brought directly to catheterization laboratory (rapid group), and 275 patients were admitted to the coronary care unit (CCU) or cardiac ward first, and then transferred to the catheterization laboratory (non-rapid group). Primary endpoint was door-to-balloon (D28) time, and secondary endpoints included infarct size assessed by peak CK-MB level and rates of major cardiac adverse events (MACE) including death, reinfarction, or target-vessel revascularization during hospitalization and at 30-day clinical follow-up.Results Baseline clinical characteristics, angiographic features and procedural success rates were comparable between the two groups, except that more patients received glycoprotein Ⅱb/Ⅲa receptor inhibitors before angiography (84.0% and 77.1, P=0.042) and had TIMI 3 flow in the culprit vessel at initial angiogram (17.1% and 9.2%, P=0.007) in the non-rapid group. The D2B time was shortened ((108±44) minutes and (138±31) minutes, P <0.0001), and number of patients with D2B time <90 minutes was greater (22.6% and 10.9%, P <0.0001) in the rapid group. The advantages associated with rapid intra-hospital transfer were enhanced if the patients presented to the hospital at regular hours. Peak CK-MB level was significantly reduced in the rapid group. In-hospital mortality (4.1% and 5.8%) and cumulative MACE rate (7.0% and 9.8%) did not significantly differ between rapid and non-rapid groups. At 30 days, cumulative death-and MACE-free survival rates were improved in the rapid group (94.5% and 89.5%, P=0.035; 90.1% and 84.0%, P=0.034, respectively).Conclusions Clinical pathway with bypass of CCU/cardiac ward admission was associated with rapid reperfusion, smaller infarct size, and improved short-term survival for patients with STEMI undergoing primary PCI. In the future, it is essential to reduce the time delay for patients presenting at off-hours.