Prevalence of electrocardiographic unrecognized myocardial infarction and its association with mortality

BACKGROUND: Identifying unrecognized myocardial infarction (MI) is important for secondary prevention. The aim of this study is to determine the prevalence and correlates of unrecognized MI and the association with mortality in the general population.

METHODS: All participants ≥18years participating in the Lifelines population, a three-generation Cohort Study and Biobank, were included (n=152,180). Participants with unrecognized MI were matched with controls without MI (1:2) based on age and gender. Unrecognized MI was defined when no history of MI was reported in combination with electrocardiographic (ECG) signs corresponding to MI. A history of MI was defined as a reported history of MI in combination with ECG signs and/or the use of antithrombotic medication.

RESULTS: MI was present in 1881(1.2%) of participants and was unrecognized in 431 (22.9%) participants. Under the age of 50years, percentages of unrecognized MI relative to the total amount of MI were 34% and 55% in men and women respectively. Compared to recognized MI, classical cardiovascular risk factors were less prevalent in participants with unrecognized MI. During a median follow- up time of 5, 4 and 4years, 4.4%, 6.4% and 2.2% of participants with unrecognized MI, recognized MI and without MI died, respectively. In a multivariable logistic regression unrecognized MI was an independent predictor of death.

CONCLUSIONS: The prevalence of unrecognized MI is substantial and classical cardiovascular risk factors are less prevalent in participants with unrecognized MI. Nevertheless, unrecognized MI is associated with mortality. Risk stratification and early diagnosis is necessary to reduce the morbidity and mortality after MI.

KEYWORDS: Electrocardiography; Lifelines; Mortality; Unrecognized myocardial infarction