No single symptom makes ACS highly likely or unlikely. For instance, the likelihood ratio (LR) for ACS/AMI of chest pain radiating to both arms or shoulders is only approximately 4–7, the LR of exertional chest pain 2.5, nausea and vomiting 2 and of positional chest pain 0.3 [6-9]. Some 30–50% of AMI patients lack chest pain [26], and among those with chest pain typical of AMI or ACS, 50% or less have it [10,11]. The chest pain quality, duration and severity are all suboptimal predictors of ACS [5,12,13]. Despite this, Inhibitors,research,lifescience,medical the ED physicians in the present study used the symptoms as the most

important factor to determine the ACS likelihood. When ACS was ruled out, the symptoms provided the decisive information – neither the ECG nor TnT contributed significantly to the assignment of

any versus no suspicion of ACS (Table 3). When symptoms were non-suspicious of ACS, Inhibitors,research,lifescience,medical the physician suspected ACS in less than one out of ten cases (Table 1). In addition, suspicions of ACS were sometimes based on symptoms alone, but almost never on ECG or TnT alone (Table 2). When the physician Inhibitors,research,lifescience,medical could not rule out (i.e. assign no suspicion of) ACS, he or she also seemed to use symptoms as the most important diagnostic modality to grade the suspicion. In the regression model comparing obvious/strong with vague/no suspicion of ACS (Table 3), the odds ratio for symptoms typical of ACS was considerably higher than for ischemic ECG and positive TnT. Further, symptoms typical of ACS were clearly more often associated with a strong suspicion of ACS Inhibitors,research,lifescience,medical than were an ischemic ECG (Tables 1 and ​and2),2), and nonspecific symptoms were in >80% of the

cases associated with a vague suspicion of ACS (Table 1). The ECG has been considered to be the most valuable ED test in patients with possible ACS, providing almost as much information as all other information Inhibitors,research,lifescience,medical combined [4,5]. This view is supported by published statistical decision support models, where ECG data have invariably been found to be crucial for the prediction of ACS in the ED, as opposed to data on symptoms and blood markers of myocardial injury [27]. In some models with ECG variables only, adding symptoms and other clinical variables did not improve ACS prediction [28]. In the present study, the ECG was find protocol indeed the most no important factor when the ED physicians identified a case of obvious ACS (Tables 1 and ​and2),2), i.e. when ACS was ruled in. However, the ECG was not considered as valuable for grading the ACS suspicion, and for ruling out ACS. A majority of patients with a normal ECG were still suspected to have ACS (Table 1), and the ECG did not contribute significantly to the assessment of any versus no suspicion of ACS (Table 3). A possible cause of this is that the shortcomings of the ECG for ACS prediction were recognized by the physicians in this study.