From 1997 to 2005, 19461 patients admitted for acute coronary syndrome in 68 hospitals in Switzerland were included in the AMIS Plus registry, of whom 11 543 showed ST segment elevation or left bundle branch block on the ECG at admission. During this period, there was an important increase in the proportion of patients treated by primary percutaneous coronary intervention (8% to 74%), and a marked reduction in the use of thrombolysis (47% to 6%) and also in the proportion of patients who did not receive any reperfusion treatment (45% to 20%). Furthermore, there was a decrease in hospital mortality (12% to 7%). Main predictors of hospital mortality were withholding PCI and thrombolysis, advanced age and the presence of cardiogenic shock. Moreover, primary PCI was associated with lower hospital mortality when compared to thrombolysis.