Association of Silent Myocardial Infarction and Sudden Cardiac Death

Abstract

IMPORTANCE Myocardial infarction in the absence of major or unrecognized symptoms are characterized as silent (SMI). The prevalence of SMI among individuals who experience sudden cardiac death (SCD), with or without concomitant electrocardiographic (ECG) changes, has not previously been described in detail from large studies to our knowledge. OBJECTIVE To determine the prevalence of SMI in individuals who experience SCD without a prior diagnosis of coronary artery disease (CAD) and to detect ECG abnormalities associated with SMI-associated SCD. DESIGN, SETTING, AND PARTICIPANTS This case-control study compared autopsy findings, clinical characteristics, and ECG markers associated with SMI in a consecutive cohort of individuals in the Finnish Genetic Study of Arrhythmic Events (Fingesture) study population who were verified to have had SCD. The Fingesture study consists of individuals who had autopsy-verified SCD in Northern Finland between 1998 and 2017. Individuals who had SCD with CAD and evidence of SMI were regarded as having had cases; those who had SCD with CAD without SMI were considered control participants. Analyses of ECG tests were carried out by investigators blinded to the SMI data. Data analysis was completed from October 2018 through November 2018. MAIN OUTCOMES AND MEASURES Silent MI was defined as a scar detected by macroscopic and microscopic evaluation of myocardium without previously diagnosed CAD. Clinical history was obtained from medical records, previously recorded ECGs, and a standardized questionnaire provided to the next of kin. The hypothesis tested was that SMI would be prevalent in the population who had had SCD with CAD, and it might be detected or suspected from findings on ECGs prior to death in many individuals. RESULTS A total of 5869 individuals were included (2459 males [78.8%]; mean [SD] age, 64.9 [12.4] years). The cause of SCD was CAD in 4392 individuals (74.8%), among whom 3122 had no history of previously diagnosed CAD. Two individuals were excluded owing to incomplete autopsy information. An ECG recorded prior to SCD was available in 438 individuals. Silent MI was detected in 1322 individuals (42.4%) who experienced SCD without a clinical history of CAD. The participants with SMI were older than participants without MI scarring (mean [SD] age, 66.9 [11.1] years; 65.5 [11.6] years; P < .001) and were more often men (1102 of 1322 [83.4%] vs 1357 of 1798 [75.5%]; P < .001). Heart weight was higher in participants with SMI (mean [SD] weight, 483 [109] g vs 438 [106] g; P < .001). In participants with SMI, SCD occurred more often during physical activity (241 of 1322 [18.2%] vs 223 of 1798 [12.4%]; P < .001). A prior ECG was abnormal in 125 of the 187 individuals (66.8%) who had SCD after SMI compared with 139 of 251 (55.4%) of those who had SCD without SMI (P = .02). CONCLUSIONS AND RELEVANCE Many individuals who experienced SCD associated with CAD had a previously undetected MI at autopsy. Previous SMI was associated with myocardial hypertrophy and SCD during physical activ...

Arrhythmic risk stratification in heart failure mid‐range ejection fraction patients with a non‐invasive guiding to programmed ventricular stimulation two‐step approach

“…6,[31][32][33] Arrhythmic SCD risk in such patients with high LVEF may originate from fibrotic scar areas of small previous myocardial infarctions or silent myocardial infarctions even without a clinical history of CAD. 34 Nowadays we acknowledge the need for protecting the HFmrEF and HFpEF patients as well, 13 which is a larger population on an epidemiological basis. 35 Populations with a relatively preserved LVEF were explored only in a few previous studies.…”

“…In fact, SCD risk is continuous through the entire LVEF spectrum with a reverse trend, the more LVEF increases the more SCD decreases, but it never abolishes even in patients with a LVEF > 50% 6,31‐33 . Arrhythmic SCD risk in such patients with high LVEF may originate from fibrotic scar areas of small previous myocardial infarctions or silent myocardial infarctions even without a clinical history of CAD 34 . Nowadays we acknowledge the need for protecting the HFmrEF and HFpEF patients as well, 13 which is a larger population on an epidemiological basis 35 .…”

Electrocardiographic associations with myocardial fibrosis among sudden cardiac death victims

“…In non-ischaemic SCD victims, the death is often the first symptom of cardiac disease, since the disease is initially diagnosed at autopsy in more than one-half of these cases 3. In ischaemic heart disease, previously asymptomatic fibrotic accumulation may be a result of previous silent myocardial infarction 27. Although the likelihood of prior diagnosis increases in parallel with disease severity at autopsy, 28% of our study subjects with substantial fibrosis had no previous cardiovascular disease diagnosis.…”

Electrocardiogram machine learning for detection of cardiovascular disease in African Americans: the Jackson Heart Study

“…Up to one-half of acute myocardial infarctions (MIs) are missed or unrecognized at the time of the event but ultimately cause heart failure 8 or sudden cardiac death (SCD). 9 An electrocardiogram (ECG) is one of the simplest, cheapest, and most widely available methods used to evaluate the heart. While ECG diagnosis of MI requires a physicians interpretation, there is a growing number of automated algorithms analysing ECG in smartphones and mobile devices.…”