In Reply: Some treatment strategies were already well established at the start of our study, whereas others were introduced during the observation period. Thus, the gradual improvement in treatment seen in the study resulted from a combination of the development of new treatment strategies proven effective in clinical trials, new treatment guidelines, and improved adherence to these guidelines.
We agree with Dr Carter that the low use of coronary angiography in STEMI patients in 1996-1997 should not be interpreted as poor adherence to guidelines since the guidelines at that time did not recommend its routine use. There are probably 2 reasons for the increased use of coronary angiography, not related to primary PCI, in Sweden between 2000 and 2007. First, 2 randomized trials during the 1990s suggested a non–statistically significant clinical benefit for rescue PCI. During the subsequent study period, there was a further increase in the number of studies supporting the use of this treatment strategy.1 Second, there were 3 large trials and a subsequent meta-analysis demonstrating that a routine invasive strategy reduced symptoms and future risk of myocardial infarction in the non-STEMI population.2 The Swedish FRISC-2 (Fragmin and Fast Revascularization During Instability in Coronary Artery Disease) trial even reported a significantly reduced mortality from an early invasive strategy at 2 years of follow-up, although this was not the case after 5 years.3- 4 We believe that these circumstances may have influenced decisions by physicians during this period, despite a lack of firm evidence and support from prevailing guidelines.