Prevalence of unrecognised myocardial infarction in a low-intermediate risk asymptomatic cohort and its relation to systemic atherosclerosis

Unrecognised myocardial infarcts (UMIs) have been described in 19-44% of the general population, with prevalence increasing by 10% per decade and their presence associated with a similar or worse prognosis than recognised myocardial infarcts (RMIs).(1,2) The majority of population-based studies have focused on the use of ECG for the detection of UMI, however not all infarcts result in pathological Q waves.(3) Late gadolinium enhancement on cardiac magnetic resonance imaging (CMR) has become the clinical
gold standard for the detection of myocardial scarring, with a significantly higher detection rate of UMIs than using ECG alone.(4) These UMIs detected on CMR have significant clinical implications, with those with evidence of myocardial scarring in the absence of clinically-apparent prior infarct more likely to have chest pain, poorer left ventricular (LV) function, and suffer from a greater number of major adverse cardiovascular events.(4,5) Earlier studies have described the prevalence of UMIs in elderly populations at high risk of cardiovascular disease. These studies, by including those with known cardiovascular disease (CVD), have thereby conflated the prevalence of UMIs in the general population.(4,6) The prevalence of UMIs in a population without prior cardiovascular events and who are not at high risk has not been previously undertaken. Furthermore, a prior study of 75-years-olds has suggested that UMIs may not be associated with traditional CVD risk factors.(7) Thus identification of a cohort considered as low or intermediate risk that have suffered from UMIs may provide insight into novel predisposing aetiological factors. The aim of this study was to investigate the prevalence of UMIs in a large, non-high risk, asymptomatic cohort, assessed with magnetic resonance imaging (MRI), and the association between UMIs and risk markers for CVD.