Vähätalo JH, Huikuri HV, Holmström LTA, et al. - In this case-control study involving 5,869 people (2,459 males [78.8%]; mean [SD] age, 64.9 [12.4] years), researchers determined the prevalence of silent myocardial infarction (SMI), defined as a scar identified by macroscopic and microscopic evaluation of myocardium without earlier diagnosed coronary artery disease (CAD), in people who experience sudden cardiac death (SCD) without a prior diagnosis of CAD and identified ECG abnormalities correlated with SMI-associated SCD. In participants with SMI, heart weight was greater. SCD occurred more often during physical activity in participants with SMI. The authors concluded that many people who underwent SCD related to CAD had a previously undetected MI at autopsy. Myocardial hypertrophy and SCD during physical activity was linked to prior SMI. In 67% of people who had an SCD after an SMI, premortem ECGs in a subset with available data were abnormal.