Longitudinal blood glucose level and increased silent myocardial infarction: a pooled analysis of four cohort studies

BACKGROUND

Fasting glucose (FG) demonstrates dynamic fluctuations over time and is associated with cardiovascular outcomes, yet current research is limited by small sample sizes and relies solely on baseline glycemic levels. Our research aims to investigate the longitudinal association between FG and silent myocardial infarction (SMI) and also delves into the nuanced aspect of dose response in a large pooled dataset of four cohort studies.

METHODS

We analyzed data from 24,732 individuals from four prospective cohort studies who were free of myocardial infarction history at baseline. We calculated average FG and intra-individual FG variability (coefficient of variation), while SMI cases were identified using 12-lead ECG exams with the Minnesota codes and medical history. FG was measured for each subject during the study's follow-up period. We applied a Cox regression model with time-dependent variables to assess the association between FG and SMI with adjustment for age, gender, race, Study, smoking, longitudinal BMI, low-density lipoprotein level, blood pressure, and serum creatinine.

RESULTS

The average mean age of the study population was 60.5 (sd: 10.3) years with median fasting glucose of 97.3 mg/dL at baseline. During an average of 9 years of follow-up, 357 SMI events were observed (incidence rate, 1.3 per 1000 person-years). The association between FG and SMI was linear and each 25 mg/dL increment in FG was associated with a 15% increase in the risk of SMI. This association remained significant after adjusting for the use of lipid-lowering medication, antihypertensive medication, antidiabetic medication, and insulin treatment (HR 1.08, 95% CI 1.01-1.16). Higher average FG (HR per 25 mg/dL increase: 1.17, 95% CI 1.08-1.26) and variability of FG (HR per 1 sd increase: 1.23, 95% CI 1.12-1.34) over visits were also correlated with increased SMI risk.

CONCLUSIONS

Higher longitudinal FG and larger intra-individual variability in FG over time were associated in a dose-response manner with a higher SMI risk. These findings support the significance of routine cardiac screening for subjects with elevated FG, with and without diabetes.

Subepicardial aneurysm with free wall rupture and its successful surgical intervention: a case report

Background

Subepicardial aneurysm (SEA) is an uncommon but potentially fatal complication of acute myocardial infarction (MI) associated with an increased risk of free wall rupture (FWR) leading to sudden death. We describe a rare case of a silent myocardial infarction complicated by SEA and subsequent FWR, resulting in cardiac tamponade.

Case summary

A 68-year-old man with no previous chest symptoms presented with syncope. Cardiac computed tomography incidentally revealed a small aneurysmal cavity at the inferolateral wall of the left ventricle, which was overlooked on initial transthoracic echocardiography. Coronary angiography demonstrated a narrowed first obtuse marginal branch with coronary slow flow, suggesting that spontaneous recanalization of the occluded obtuse marginal branch induced SEA and subsequent FWR. The patient underwent an emergency left ventricular aneurysm repair. The post-operative course was uneventful, and the patient was discharged from the hospital on post-operative day 20.

Discussion

This case emphasizes the importance of prompt detection and surgical intervention for SEA. Subepicardial aneurysm should be suspected in patients with pericardial effusion and suspected MI. Cardiac computed tomography is not only useful in the detection of such cases but also facilitates the development of a successful surgical strategy.

The utility of silent myocardial infarction on electrocardiogram as an ASCVD risk enhancer for primary prevention: The multi-ethnic study of atherosclerosis

BACKGROUND

The 2018 AHA/ACC cholesterol guidelines introduced a new list of markers called "risk enhancers" that, if present, confer an increased risk of atherosclerotic cardiovascular disease (ASCVD). Silent myocardial infarction (SMI) on electrocardiogram (ECG) is notably absent, even though it associated with future ASCVD.

METHODS

We assessed the utility of SMI on ECG as a risk-enhancer in intermediate-risk participants in MESA (Multi-Ethnic Study of Atherosclerosis) - those with 10-year ASCVD risk of 5-20% by the pooled cohort equation (PCE). SMI was defined as major Q-wave abnormality or minor Q/QS waves in the setting of major ST-T abnormalities without prevalent clinical cardiovascular disease.

RESULTS

Among 2946 participants (mean age 63.1 ± 7.6, 53.9% women, 36% white, 11% Chinese-American, 33% African-American, 19% Hispanic), 66 (2.2%) had SMI at baseline. After a median 15.8 years of follow-up, incident ASCVD events occurred in 431/2876 (15.0%) of those without SMI and 16/66 (24.2%) of those with SMI. In a multivariable-adjusted Cox proportional hazards model, baseline SMI was associated with an increased risk of incident ASCVD events (HR 1.68, 95% CI 1.02-2.77, p = 0.04). However, adding SMI to the PCE did not improve discrimination and reclassification was modest-net reclassification improvement was 0.0161 (95% CI 0.002-0.034, p = 0.08).

CONCLUSION

Our findings suggest that the prevalence of SMI is 2.2% among those without known clinical cardiovascular disease considered intermediate-risk by the PCE. In our analysis, SMI only modestly improved classification of risk, suggesting that it may not be very useful as an ASCVD risk enhancer.

Reprint of "Electrocardiographic definition of silent myocardial infarction in population studies: A call to standardize the standards"

According to the American Heart Association, 170,000 new silent myocardial infarctions (SMI) occur annually in the United States. Prior studies from the general population also have shown that SMI is common, but the rates varied widely. Some studies reported SMI rates as low as 4% while others reported rates as high as 57% of the total MIs. Reports on the prognostic significance of SMI compared to clinically recognized MI also have been inconsistent. Although SMI could be detected using cardiac imaging, electrocardiogram (ECG) has been the most common method for detection of SMI in both clinical and research settings due to it is low-cost and wide availability. This report highlights certain ECG methodological aspects that need to be taken into consideration when interpreting findings from population studies addressing SMI. Examples from population studies will be used in this report to show how deviation and differences in applications of the ECG standard definitions of SMI, ECG processing methods, and the frequency of ECG recording in population studies could impact the results, which may explain the wide range of rates and inconsistent conclusions about the prognostic significance of SMI. A summary of the gaps in knowledge of the SMI research is provided. By highlighting the lack of uniform approach in defining SMI despite the availability of standard definitions and pointing out the gaps in knowledge, it is hoped that a call for standardizing the use of the current standards will emerge.

A silent myocardial infarction with normal coronary arteries associated with Graves' disease

Acute myocardial infarction (AMI) is a scarce but fatal complication in Graves' disease (GD). Silent myocardial infarction (MI) associated with GD has never been reported. A 37-year-old male patient was admitted due to poorly controlled hyperthyroidism and persistent fever. But the patient did not complain of chest pain on admission. The electrocardiogram (ECG) showed Q waves and ST-segment elevations. Cardiac troponin I (cTnI) was sharply increased. He was qualified to an emergency coronary angiography which showed normal coronary arteries without any stenosis. The potential mechanisms for AMI with angiographically normal coronary arteries in the setting of hyperthyroidism may be attributed to the hyper-metabolic state due to thyrotoxicosis, severe vasospasm in coronary artery, coagulation abnormalities, and the inflammatory/autoimmune milieu. In conclusion, patients with GD-associated silent MI are unusual. Early recognition and diagnosis by clinicians provide a better prognosis. This case demonstrates the importance of ECG and cTnI screening among GD patients.

Electrocardiographic QRS-T angle and the risk of incident silent myocardial infarction in the Atherosclerosis Risk in Communities study

BACKGROUND

Silent myocardial infarction (SMI) accounts for about half of the total number of MIs, and is associated with poor prognosis as is clinically documented MI (CMI). The electrocardiographic (ECG) spatial QRS/T angle has been a strong predictor of cardiovascular outcomes. Whether spatial QRS/T angle also is predictive of SMI, and the easy-to-obtain frontal QRS/T angle will show similar association are currently unknown.

METHODS

We examined the association between the spatial and frontal QRS/T angles, separately, with incident SMI among 9498 participants (mean age 54years, 57% women, and 20% African-American), who were free of cardiovascular disease at baseline (visit 1, 1987-1989) from the Atherosclerosis Risk in Communities (ARIC) study. Incident SMI was defined as MI occurring after the baseline until visit 4 (1996-1998) without CMI. The frontal plane QRS/T angle was defined as the absolute difference between QRS axis and T axis. Values greater than the sex-specific 95th percentiles of the QRS/T angles were considered wide (abnormal).

RESULTS

A total of 317 (3.3%) incident SMIs occurred during a 9-year median follow-up. In a model adjusted for demographics, cardiovascular risk factors and potential confounders, both abnormal frontal (HR 2.28, 95% CI 1.58-3.29) and spatial (HR 2.10, 95% CI 1.44-3.06) QRS/T angles were associated with an over 2-fold increased risk of incident SMI. Similar patterns of associations were observed when the results were stratified by sex.

CONCLUSIONS

Both frontal and spatial QRS/T angles are predicative of SMI suggesting a potential use for these markers in identifying individuals at risk.

The AngelMed Guardian system: Is there a role for implantable devices for early detection of coronary artery occlusion?

The AngelMed Guardian System is an implantable device similar to a single chamber pacemaker that continuously monitors the intracardiac electrogram for evidence of ST segment shift indicating acute coronary artery occlusion. The system aims to reduce time to presentation by alerting patients to present to a medical facility whether symptoms are present or not. In March 2016, the US Food and Drug Administration (FDA) assembled a meeting of the Circulatory System Devices Panel to review the results of the AngelMed for Early Recognition and Treatment of STEMI (ALERTS) pivotal trial and the accompanying premarket approval (PMA) application for regulatory approval of the AngelMed Guardian System in the US. In this review, we examine the ALERTS trial methodology and results, and describe the FDA panel's deliberations and recommendations.

Association of cardiovascular disease risk factors with left ventricular mass, biventricular function, and the presence of silent myocardial infarction on cardiac MRI in an asymptomatic population

The purposes of this study were to evaluate the relationship between risk factors for cardiovascular disease (CVD) and cardiac mass and function on cardiac magnetic resonance imaging (MRI), and to investigate possible risk factors for silent myocardial infarction (SMI) in an asymptomatic Asian population. We included 647 asymptomatic subjects (485 males, mean age 54.8 ± 6.7 years; 162 females, mean age 55.2 ± 7.6 years) who underwent 1.5-T cardiac MRI during a health checkup. The association between biventricular functional parameters as evaluated on MRI and CVD risk factors was examined using multivariable regression and analysis of variance. The left ventricular mass-to-volume ratios were positively related to body mass index (β = 0.153, p < 0.001), systolic (β = 0.165, p = 0.001) and diastolic (β = 0.147, p = 0.002) blood pressure, triglyceride levels (β = 0.197, p = 0.006), and C-reactive protein levels (β = 0.130, p < 0.001), and were negatively related to estimated glomerular filtration rates (β = -0.076, p = 0.025). No significant relationship was present between ventricular parameters and the presence of SMI after adjusting for confounders. The prevalence (6.9 %, 7/101) of SMI in diabetics was significantly greater than that in non-diabetics patients (0.9 %, 5/546; confidence interval 1.739-12.848; p < 0.001). Traditional CVD risk factors are associated with ventricular mass, geometry and function in asymptomatic subjects. Silent MI may not independently influence ventricular mass and function and diabetes mellitus may contribute to the development of SMI.

A rare long-term survival of the life-threatening trio: silent myocardial infarction complicated by ventricular septal rupture, type 2 diabetes mellitus and chronic bronchitis

Silent myocardial infarction followed by ventricular septal rupture (VSR) is a rare phenomenon. In the absence of a timely diagnosis and surgical correction, the short term mortality of such patients is greater than 90%. We present one such unique case of a patient with an asymptomatic myocardial infarction complicated by VSR, type 2 diabetes mellitus and chronic bronchitis. Unfortunately, this possibly life-threatening condition had been misdiagnosed for more than one month after initial medical contact. Lack of typical symptoms of chest pain and chronic bronchitis is primarily responsible for this long-time misdiagnosis. We want to emphasize the importance of systematic diagnostic work-up, high vigilance for possibility of VSR complicating myocardial infarction in aged patients with diabetes and chronic bronchitis, which may mislead doctors' judgments and put patients at high risk.

An unusual case of silent acute ST-elevation myocardial infarction following amphetamine use

We report a case of silent acute ST-elevation myocardial infarction associated with amphetamine use in a 62 years old diabetic man. The patient was devoid of chest pain and had a normal cardiac enzyme analysis at the initial presentation. A routine electrocardiogram demonstrated acute inferior wall ST-elevation myocardial infarction. Coronary angiography confirmed a total occlusion of the posterior lateral branch of right coronary artery. The patient underwent successful percutaneous transluminal coronary angioplasty with stent placement. Amphetamine abuse may play a role in acute myocardial infarction. Adverse cardiovascular manifestations of amphetamine can occur with sudden overt chest pain or present insidiously. In view of the potential association of amphetamine and myocardial infarction, physicians should not rely only upon clinical symptoms. This report highlights the diabetic patients with amphetamine abuse should undergo a routine electrocardiogram in such circumstances.