Incidence, frequency and clinical characteristics of type 3 myocardial infarction in clinical practice

Abstract Objectives Cardiac death in a patient with symptoms and electrocardiographic changes indicative of myocardial ischemia but without available measurements of cardiac biomarkers is designated a type 3 myocardial infarction. We wanted to investigate the incidence, the frequency and the characteristics of patients diagnosed as type 3 myocardial infarction. Methods The occurrence of deaths in a well-defined geographic region was retrieved from the Danish Civil Registration System during a one-year period from 2010 to 2011. Complementary data concerning causes of deaths were obtained from the Danish Register of Causes of Death, ambulance and hospital patient files. Adjudication of the diagnosis was done by two local experts and one external senior cardiologist. Results A total of 2766 of the 246.723 adult residents in the region had died. A type 3 myocardial infarction was diagnosed in 18 individuals, corresponding to an annual incidence of 7.3/100.000 person years. During the same one-year period 488 patients had other types of myocardial infarction implying a 3.6% frequency of type 3 myocardial infarction (18 of 506) among all myocardial infarctions. Conclusions Type 3 myocardial infarction is a rare observation in clinical practice with an annual incidence below 10/100.000 person years and a frequency of 3-4% among all types of myocardial infarction. If autopsy data are included the number of type 3 myocardial infarctions will increase.