Silent myocardial infarction (MI) or heart attack is a condition when blood flow to a part of the heart stops or decreases without any prior symptoms. However, the association of sudden MI with sudden cardiac death (SCD) has not been well studied. This study aims to investigate the prevalence of silent MI in individuals who experienced SCD.

 This case-control study included a total of 5,869 individuals (mean age 64.9, 78.8% males) who had SCD with coronary artery disease (CAD), along with evidence of silent MI (cases) or those who had SCD with CAD without silent MI (control). The primary outcome of the study was silent MI as a scar without previously diagnosed CAD.

The cause of SCD was found to be CAD in 4,392 individuals (74.8%), of whom 3,122 had no history of CAD. Silent MI was diagnosed in 1,322 patients (42.4%) who experienced SCD without a history of previously diagnosed CAD. The findings also suggested that participants with SMI were older than participants without MI scarring.

The research concluded that individuals who experienced SCD associated with CAD had a previously silent MI at autopsy. Further, previously undetected MI was associated with SCD and myocardial hypertrophy during physical activity.