Silent myocardial infarction often precedes sudden cardiac death


A silent myocardial infarction is not without danger. A Finnish case-control study conducted over a 20-year period and involving nearly 6000 patients has revealed that 40% of sudden cardiac death cases had previously been victims of an undetected myocardial infarction, defined by the presence of a myocardial scar upon autopsy.

The Finish investigators observed that coronary artery disease was responsible for the sudden cardiac death in 74.8 % of subjects (n=4392), with no prior diagnosis of coronary artery disease made in 71.2 % of cases (n=3122). Among the latter, a silent myocardial infarction was detected in 42 .4% of patients who died of sudden death with any antecedents of coronary artery disease.

Between the victims with silent myocardial infarction and those who lacked evidence of scarring, multiple significant (p <0,001) differences were revealed. The victims tended to be older, were more likely to be men, had a more hypertrophied heart, and were more likely to die during physical activity.

For 438 patients, ECGs carried out shortly before the patients’ deaths were available. Among the victims with ECG results available, abnormal ECG findings were present in about two-thirds of the patients (66 .8%), such as QRS complex fragmentations, presence of a Q wave, T wave inversion, and QRS ≥110 msec. Based on these findings, the investigators drew the conclusion that silent myocardial infarction is common among patients who go on to experience sudden cardiac death, as most ofthese patients had already previously been victims of myocardial infarction, without any correct diagnosis being made.

Reference: Vähätalo JH, Huikuri HV, Holmström LTA, et al. Association of Silent Myocardial Infarction and Sudden Cardiac Death. JAMA Cardiol. 2019 Jul 10. doi: 10.1001/jamacardio.2019.2210. [Epub ahead of print]