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Background: Silent or unrecognized myocardial infarction (UMI) diagnosed by surveillance electrocardiography (ECG) carries similarly poor prognosis as recognized MI (RMI) for poorly understood reasons., Methods: This study included 5430 consecutive patients who presented to the nuclear laboratory and underwent 2-day stress and rest Tc- 99m sestamibi and ECG studies between March 1991 and June 1999. UMI was diagnosed if ECG showed Q-wave MI in the absence of a history of RMI. We measured infarct size (% defect size as compared with the entire left ventricular sestamibi uptake), ejection fraction (EF, %), and summed difference score (SDS, sestamibi uptake by myocardium in stress minus sestamibi uptake in rest images as a marker of ischemia). Survival was determined by follow-up survey (median 6 years)., Results: We identified 346 UMIs, 628 RMIs, and 4456 subjects without MI (No MI). As compared with RMI, UMI patients had lesser abnormalities on nuclear scans (p < .0001 for all), including smaller infarct size (5.7% vs. 12.2%), higher EF (58% vs. 53%), and lesser ischemia (SDS; 3.9% vs. 2.7%). UMI prognosis was as poor as that of RMI (annual mortality rate 4.7% vs. 4.8% with No MI rate of 2.9%; p < .001 for all comparisons), and this persisted after multivariate analysis. Infarct size quantification successfully risk-stratified ECG-UMI patients, but UMI patients continued to predict mortality even if the infarct size was 0%., Conclusions: Although UMI patients have lesser abnormalities on nuclear scans, ECG-based UMI continues to independently predict mortality, indicating the continuing relevance of ECG in clinical practice., (© 2023 The Authors. Annals of Noninvasive Electrocardiology published by Wiley Periodicals LLC.)

Background: After the introduction of the universal definition of myocardial infarction, the incidence and diagnosis of type 2 myocardial infarction have risen dramatically, yet there are no clear guidelines on clinical management. Diabetic patients are at high risk for developing type 2 myocardial infarction when admitted in a decompensated state, and they are also at high risk for future cardiovascular events., Methods: We performed a retrospective analysis of 1058 patients admitted with diabetic ketoacidosis or hyperosmolar hyperglycemic state between 2011 and 2016. Patients were included if they had cardiac troponin I measured within 24 hours of admission, were older than 18 years of age, and had no evidence of acute coronary syndrome on admission. Baseline characteristics, admission laboratory test results, major adverse cardiovascular events, cardiac stress testing, and coronary angiography data up to 1 year after admission were reviewed. Patients were categorized into 2 groups: those with and those without type 2 myocardial infarction. The study had 2 endpoints: mortality and major adverse cardiac events (MACE) at 1 year and an abnormal result on stress test or coronary angiography at 1 year., Results: Of the 845 patients who met the inclusion criteria, 133 patients (15%) had type 2 myocardial infarction on admission. Patients with type 2 myocardial infarction were at a significantly higher risk for mortality and MACE at 1 year than those without. Patients with type 2 myocardial infarction were also at higher risk for developing an abnormal result on stress test or coronary angiography within 1 year of admission as compared with those without type 2 myocardial infarction (40% vs 24%; odds ratio 2; P = .0699)., Conclusion: Acutely decompensated diabetic patients with type 2 myocardial infarction are at increased risk for death and MACE. These patients may also be at risk for undiagnosed coronary artery disease., (Copyright © 2018 Elsevier Inc. All rights reserved.)

A rapid diagnosis of ST-segment elevation myocardial infarction (STEMI) is mandatory for optimal treatment of an acute coronary syndrome. However, a small number of patients with suspected STEMI are afflicted with other medical conditions. These medical conditions are rare, but important clinical entities that should be considered when evaluating a STEMI alert. These conditions include coronary vasospasm, Takotsubo cardiomyopathy, coronary arteritis/aneurysm, myopericarditis, Brugada syndrome, left bundle branch block, early repolarization, aortic dissection, infective endocarditis with root abscess, subarachnoid hemorrhage, ventricular aneurysm after transmural myocardial infarction, and hemodynamically significant pulmonary embolism with right ventricular strain. Herein, we present several STEMI mimickers.

Background: The relationship between electrocardiographic unrecognized myocardial infarction (UMI), abnormal functional status, echocardiographic abnormalities, and mortality has not been evaluated., Methods: A population-based random sample of 2042 Olmsted County residents, age > or = 45 years, was studied by self-administered questionnaire, chart review, ECG and echocardiogram, and 5 year follow-up for all-cause mortality. UMI (n = 81) was diagnosed if ECG-MI criteria were met without previous documented myocardial infarction. Functional Status was assessed by the Goldman Specific Activity Scale., Results: UMI subjects had an increased prevalence of abnormal functional status compared to no MI controls (22% vs 11%, P < 0.05). This association was independent of sex, obesity, smoking, diabetes, and pulmonary disease. It became insignificant after stratifying for echocardiographic abnormalities. Compared to no MI controls, UMI subjects with impaired functional status had a higher mortality hazard ratio (HR 7.2; P<0.0001) than those without impaired functional status (HR 2.7; P = 0.02). In UMI subjects with impaired functional status and any echocardiographic abnormality signifying global ventricular dysfunction (systolic or diastolic dysfunction, left atrial or left ventricular enlargement), the mortality risk was even higher (HR 9.5; P<0.001) and persisted in multivariate analyses. This increased mortality risk was unaffected by adjustment for regional wall motion abnormalities., Conclusions: The assessment of impaired functional status and echocardiographic abnormalities improves the prognostic significance of UMI. Even in the absence of regional wall motion abnormalities, structural abnormalities of global dysfunction may play a role in mediating the increased mortality associated with UMI.

Background: There are very few data describing the association of electrocardiogram-based unrecognized myocardial infarction (ECG-UMI) with nonanginal cardiopulmonary symptoms, echocardiographic abnormalities, and mortality in the community., Methods: We studied 2042 Olmsted County residents, who were randomly selected and aged > or = 45 years, by a survey questionnaire for symptoms, echocardiogram for structural abnormalities, and a 5-year follow-up for all-cause mortality. Unrecognized myocardial infarctions (n = 81) were diagnosed if ECG-based myocardial infarction (MI) criteria were met without the history of a documented recognized MI., Results: In UMI versus no MI controls, the prevalence (%) of dyspnea on exertion (49 vs 29), orthopnea (6 vs 4), palpitations (20 vs 15), and history of fluid overload (6 vs 1) was significantly higher (P < .05). The associations of exertional dyspnea and history of fluid overload with UMI were independent of age, sex, and pulmonary disease but had a significant reduction in their magnitude after adjusting for global dysfunction (diastolic or systolic dysfunction). All the 4 symptoms were associated with increased risk of mortality (hazard ratios ranging from 2.3 to 9.1, P < .0001), which was meaningfully attenuated by adjusting for ECG-UMI status. Global ventricular dysfunction had a more significant impact on this association than regional ventricular dysfunction (wall motion abnormalities)., Conclusions: The increased risk of mortality associated with symptoms is at least in part mediated via ECG-UMI. Structural abnormalities of global dysfunction play a greater role in mediating this risk than regional dysfunction, challenging the current clinical practice of calling an ECG-based MI false positive in symptomatic adults in the absence of wall motion abnormalities.

Unrecognized myocardial infarction (UMI) as diagnosed by surveillance electrocardiography has been shown to carry the same poor prognosis as recognized myocardial infarction (RMI). The echocardiographic characteristics of UMI have never been studied before. Due to a similar prognosis, we hypothesized that UMI and RMI would exhibit similar degrees of echocardiographic ventricular dysfunction. We studied a random community cohort of 2,042 adults who were > or =45 years of age in a cross-sectional setting in Olmsted County, Minnesota. RMI was diagnosed by review of medical records and UMI was diagnosed if the electrocardiogram met MI criteria without a previous MI recorded in the medical record. All subjects underwent transthoracic echocardiography. We identified 80 patients who had UMI and 101 who had RMI. In bivariate analyses, a stepwise increase in echocardiographic abnormalities was observed from participants who had no MI to UMI to RMI: respective mean ejection fractions were 63%, 61%, and 55; prevalences in left ventricular enlargement were 13%, 22%, and 52%; mean left ventricular mass indexes were 98, 103, and 118 g/m(2); prevalences in regional wall motion abnormality were 2%, 13%, and 42%; and prevalences in diastolic dysfunction were 25%, 56%, and 65% (p for trend <0.0001 for all comparisons). After adjusting for standard coronary risk factors, patients who had UMI continued to exhibit significant abnormalities in systolic dysfunction, diastolic dysfunction, and regional wall motion abnormality, although to a lesser extent than patients who had RMI. In conclusion, patients who have UMI manifest structural abnormalities more commonly than do patients who have no MI but less commonly than do those who have RMI. The similar prognosis after UMI and RMI cannot be explained by comparable degrees of ventricular damage.

Background: Despite using the same tool (ECG), the proportion of myocardial infarctions that goes unrecognized varies from 20% to 60% in population-based studies. The reasons for such wide variations have not been studied. We sought to evaluate the effect of ECG-MI criteria and study methodology on the prevalence of unrecognized myocardial infarction (UMI) and to identify the optimal ECG-MI criteria for UMI detection in epidemiologic studies., Methods: A random population-based sample of 2042 adults, age > or = 45 years, underwent history, medical record abstraction and ECG. Six different ECG-MI criteria and two subjective recognized myocardial infarction (RMI) identification criteria, from different published studies, were applied to the same survey ECG. The operating test characteristics of different criteria were compared with the objective criterion standard of a RMI by Gillum criteria., Results: The UMI proportion estimates varied from 32% to 61% due to variation in ECG-MI criteria, while keeping the study population, MI recognition criteria, and ECG constant. Subjective criteria for MI recognition had limited value (positive predictive value of 44-93%) in picking up RMI. Depending on the ECG abnormality used to define MI, ECG reading had widely varying sensitivity (21-37%; P < 0.0001) with consistently high specificity (92-97%) for detection of RMI., Conclusions: The prevalence estimates of UMI vary widely and are strongly dependent on the ECG-MI and MI recognition criteria. Future studies of UMI should explicitly recognize this variation and select the ECG-MI criteria that match their study aims.

Background: Unrecognized myocardial infarctions (UMI) are detected by surveillance electrocardiograms (ECGs). In epidemiologic studies, different sets of ECG criteria have been used to define myocardial infarction, possibly contributing to significant differences in prevalence estimates and risk factor associations. We sought to summarize the rationale behind the various UMI-ECG definitions and to suggest an approach to develop uniform criteria., Methods: A comprehensive review of relevant publications from 1966 to 2002 was conducted., Results: Out of 14 major studies, the occurrence of UMI as a proportion of all infarctions varied from 4% to 44%, with markedly varying ECG criteria. No study directly addressed the rationale behind selection of ECG criteria. Computerized ECG analysis appears superior to visual reading due to better reliability, speed and cost while maintaining a similar predictive validity. Criteria requiring only major Q waves have the highest specificity for ECG-MI and for prediction validity for future coronary heart disease in middle-aged white men. The addition of minor Q waves and ST-T abnormalities improves predictive validity in middle-aged women and elderly men. Minor Q waves can have their diagnostic accuracy improved by several strategies, including use of ST-T wave changes, Washington Code, vector cardiogram, chronic obstructive pulmonary disease-ECG criteria, and serial ECG analysis., Conclusion: Currently the most cost-effective and valid method for detecting UMI in epidemiologic studies appears to be computerized ECG analysis using major Q waves in middle-aged white men. Issues needing further research include morphologic validation of ECG-UMI criteria and the influence of age, sex, and race on ECG-MI criteria.