We found the known Compound-K markers for the likelihood of CAD, such as atherosclerotic disease of cerebral or peripheral arteries, diabetes, chronic pulmonary disease, and renal insufficiency to be associated with absence of ST-elevations. This most likely reflects the protective role of coronary collaterals from ST-elevation in addition to an increased likelihood for small side branch occlusion. In addition to a higher likelihood for development of chronic CAD, diabetes has multiple effects on risk of myocardial infarction including alterations in artery wall and plaque remodeling and thrombogenesis. Atrial fibrillation was also associated with MI without ST-elevations in our study. This may be due to ongoing oral anticoagulation therapy for stroke prevention that also prevents formation of totally occlusive coronary thrombus. Our finding of association between malignancy and absence of ST-elevations is in agreement of a previous study of MI in cancer patients, and is likely to be due to cancer related abnormalities in coagulation and thrombosis, and the effects of anticancer therapies. Previous studies originating from US, Ireland, and Italy have reported constantly declining proportions of STEMI among MI patients in recent years. We found the proportion of STEMI to slightly decline during 2001�C2004, but contradictory to previous findings, proportion of STEMI steadily increased from 2004 onwards. Reasons for this discrepancy require further study, but the end in the decline of blood pressures in addition to increase in obesity and binge drinking during recent years in Finland are potential contributors. The current study has limitations associated with use of retrospective hospital registry data. Thus, diagnoses were made by treating physicians, which may have affected the included patient population. Hospital discharge data has, however, proved to be a valuable source of Sipeimine information on cardiovascular disease. The nationwide hospital discharge registry utilized here is government maintained, automatic, and mandatory thus capturing information of all hospital admissions and resulting in accurate information on cardiovascular disease. In addition to a small number of inevitable coding inaccuracies, diagnostic inaccuracies may be a potential source of error. As treatment choices in MI rely heavily on distinction between STEMI and NSTEMI, the correct interpretation of electrocardiography and resulting diagnostic classification are however major priorities among physicians treating patients with an acute coronary syndrome. In order to minimize misdiagnosis of MI in chest pain patients with non-coronary causes such as extra-cordial pain, myocarditis, aortic dissection, or pulmonary embolism we included only patients treated in hospitals with coronary angiolaboratory. Therefore, patients who did not reach hospital due to e.g. sudden cardiac death associated with myocardial infarction were not included. In conclusion, myocardial infarction presents with ST-elevations more commonly in men and the presence of ST-elevations decreases with increasing age. Diabetes, atrial fibrillation, peripheral or cerebral artery disease, chronic pulmonary disease, malignancy, and renal insufficiency are associated with absence of ST-elevations in myocardial infarction. These findings may help to predict likelihood of ST-elevations in a patient with myocardial infarction. There are several important 
considerations when designing randomized libraries of protein variants. The mutagenesis method used should produce the required kind and range of variability.