Midlife Cardiovascular Risk Factors and Late-Life Unrecognized and Recognized Myocardial Infarction Detect by Cardiac Magnetic Resonance: ICELAND-MI, the AGES-Reykjavik Study

Effect of Intensive Blood Pressure Lowering on the Risk of Incident Silent Myocardial Infarction: A Post Hoc Analysis of a Randomized Controlled Trial

BACKGROUND

Silent myocardial infarction (SMI) frequently goes undetected, yet it is associated with increased cardiovascular morbidity and mortality. The impact of intensive systolic blood pressure (SBP) lowering on the risk of SMI in those with hypertension remains uncertain.

METHODS

In this post hoc analysis of the Systolic Blood Pressure Intervention Trial (SPRINT), participants with serial electrocardiograms (ECGs) during the trial were included. SPRINT investigated the benefit of intensive SBP lowering, aiming for < 120 mmHg compared to the standard SBP goal of < 140 mmHg. Incident SMI was defined as evidence of new MI on an ECG without adjudicated recognized myocardial infarction (RMI).

RESULTS

During a median follow-up of 3.9 years, a total of 234 MI events (55 SMI and 179 RMI) occurred. Intensive, compared to standard, SBP lowering resulted in a lower rate of SMI (incidence rate 1.1 vs. 2.3 cases per 1000 person-years, respectively; HR [95% CI]: 0.48 [0.27-0.84]). Similarly, intensive, compared to standard, BP lowering reduced the risk of RMI (incidence rate 4.6 vs. 6.5 cases per 1000 person-years, respectively; HR [95% CI]: 0.71 [0.52-0.95]). No significant differences were noted between the strength of the association of intensive BP control on lowering the risk of SMI and RMI (p-value for HR differences = 0.23).

CONCLUSIONS

This study shows that in adults with hypertension, the benefits of intensive SBP lowering, compared with standard BP lowering, go beyond the prevention of RMI to include the prevention of SMI.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01206062.

Associations of Midlife and Late-Life Blood Pressure Status With Late-Life Retinal OCT Measures

Purpose

To explore the relationship of long-term blood pressure (BP) patterns with late-life optical coherence tomography (OCT) structural measures reflecting optic nerve health.

Methods

Participants in this community-based cohort study of black and white individuals were part of the Atherosclerosis Risk in Communities study and the nested Eye Determinants of Cognition (EyeDOC) study. Participants had BP measured six times from 1987 to 2017 and were categorized into five BP patterns: sustained normotension; midlife normotension, late-life hypertension (systolic BP [SBP] >140 mmHg or diastolic BP [DBP] >90 mmHg or antihypertensive medication use); sustained hypertension; midlife normotension, late-life hypotension (SBP <90 mmHg or DBP <60 mmHg); and midlife hypertension, late-life hypotension. Multivariable linear regression modeling was used to evaluate associations between BP patterns and late-life OCT ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (RNFL) thickness.

Results

In total, 931 eyes of 931 participants (mean age at EyeDOC visit = 80 years; 63% female; 45% black) were included. Mean GCC and RNFL thicknesses in the sustained normotension pattern were 90.8 ± 10.3 µm and 89.9 ± 11.2 µm versus 89.4 ± 11.9 µm and 90.1 ± 12.2 µm in the sustained hypertension pattern (P > 0.05). Compared to the sustained normotension pattern, no significant differences in GCC or RNFL thickness were found for any anomalous BP pattern.

Conclusions

Assessment of long-term BP status showed no significant associations with late-life OCT structural measures.

Translational Relevance

OCT imaging results in our population-based sample suggest that neither hypertension, even when present in midlife, nor late-life hypotension are significant risk factors for late-life optic nerve damage.

MIKB: A manually curated and comprehensive knowledge base for myocardial infarction

Myocardial infarction knowledge base (MIKB; http://www.sysbio.org.cn/mikb/; latest update: December 31, 2020) is an open-access and manually curated database dedicated to integrating knowledge about MI to improve the efficiency of translational MI research. MIKB is an updated and expanded version of our previous MI Risk Knowledge Base (MIRKB), which integrated MI-related risk factors and risk models for providing help in risk assessment or diagnostic prediction of MI. The updated MIRKB includes 9701 records with 2054 single factors, 209 combined factors, 243 risk models, 37 MI subtypes and 3406 interactions between single factors and MIs collected from 4817 research articles. The expanded functional module, i.e. MIGD, is a database including not only MI associated genetic variants, but also the other multi-omics factors and the annotations for their functional alterations. The goal of MIGD is to provide a multi-omics level understanding of the molecular pathogenesis of MI. MIGD includes 1782 omics factors, 28 MI subtypes and 2347 omics factor-MI interactions as well as 1253 genes and 6 chromosomal alterations collected from 2647 research articles. The functions of MI associated genes and their interaction with drugs were analyzed. MIKB will be continuously updated and optimized to provide precision and comprehensive knowledge for the study of heterogeneous and personalized MI.

Sex-Based Differences in Unrecognized Myocardial Infarction

Background

Myocardial infarction is an important cause of morbidity and mortality in both men and women. Atypical or the absence of symptoms, more prevalent among women, may contribute to unrecognized myocardial infarctions and missed opportunities for preventive therapies. The aim of this research is to investigate sex‐based differences of undiagnosed myocardial infarction in the general population.

Methods and Results

In the Lifelines Cohort Study, all individuals ≥18 years with a normal baseline ECG were followed from baseline visit till first follow‐up visit (≈5 years, n=97 203). Individuals with infarct‐related changes between baseline and follow‐up ECGs were identified. The age‐ and sex‐specific incidence rates were calculated and sex‐specific cardiac symptoms and predictors of unrecognized myocardial infarction were determined. Follow‐up ECG was available after a median of 3.8 (25th and 75th percentile: 3.0–4.6) years. During follow‐up, 198 women experienced myocardial infarction (incidence rate 1.92 per 1000 persons‐years) compared with 365 men (incidence rate 3.30; P<0.001 versus women). In 59 (30%) women, myocardial infarction was unrecognized compared with 60 (16%) men (P<0.001 versus women). Individuals with unrecognized myocardial infarction less often reported specific cardiac symptoms compared with individuals with recognized myocardial infarction. Predictors of unrecognized myocardial infarction were mainly hypertension, smoking, and higher blood glucose level.

Conclusions

A substantial proportion of myocardial infarctions are unrecognized, especially in women. Opportunities for secondary preventive therapies remain underutilized if myocardial infarction is unrecognized.

Stress-Only Adenosine CMR Improves Diagnostic Yield in Stable Symptomatic Patients With Coronary Artery Calcium

OBJECTIVES

This study assessed whether adenosine stress-only perfusion cardiac magnetic resonance (CMR) following a positive coronary artery calcium (CAC) score improved the diagnostic yield of invasive coronary angiography (CAG) in patients with stable chest pain. The study also established the association between positive CAC scores and stress-induced myocardial ischemia.

BACKGROUND

The diagnostic yield of catheterization among patients with suspected coronary artery disease (CAD) is low. Improved patient selection and diagnostic testing are necessary. The CAC score can minimize unnecessary diagnostic testing, and in low-risk patients, normal CMR results have a high negative predictive value. Less comprehensive protocols may be sufficient to guide further work-up.

METHODS

A total of 642 consecutive patients (mean age: 63 years; 50% women) with stable chest pain and CAC scores of >0 who were referred for CMR were enrolled. Patients with a perfusion defect were subsequently examined by CAG. Patients were followed up for 1 year. Outcome was obstructive CAD.

RESULTS

Obstructive CAD was present in 12% of patients. For CAD diagnosis, the sensitivity of adenosine CMR was 90.9% (95% confidence interval [CI]: 88.7 to 93.1), specificity was 98.7% (95% CI: 97.9 to 99.6), positive predictive value was 92.0% (95% CI: 89.8 to 94.1), and negative predictive value was 98.6% (95% CI: 97.6 to 99.5). A CAC score between 0.1 and 100 without typical angina was associated with obstructive CAD in only 3% of patients. Patients with nonanginal chest pain and a CAC score ≥400 had obstructive CAD (16%).

CONCLUSIONS

Stress-only adenosine CMR had high diagnostic accuracy and served as an efficient gatekeeper to CAG in stable patients with a CAC score >0. Patients with CAC scores between 0.1 and 100 could be deferred from further testing in the absence of clinical features that suggested high risk. However, in patients with CAC score ≥400, functional testing should be indicated, regardless of the type of chest pain.

Association Between Unrecognized Myocardial Infarction and Cerebral Infarction on Magnetic Resonance Imaging

Importance

It is uncertain whether unrecognized myocardial infarction (MI) is a risk factor for cerebral infarction.

Objective

To determine whether unrecognized MI detected by cardiac magnetic resonance imaging (MRI) is associated with cerebral infarction.

Design, Setting, and Participants

This is a cross-sectional study of ICELAND MI, a cohort substudy of the Age, Gene/Environment Susceptibility-Reykjavik Study conducted in Iceland. Enrollment occurred from January 2004 to January 2007 from a community-dwelling cohort of older Icelandic individuals. Participants aged 67 to 93 years who underwent both brain MRI and late gadolinium enhancement cardiac MRI were included. Data analysis was performed from September 2018 to March 2019.

Exposures

Unrecognized MI identified by cardiac MRI.

Main Outcomes and Measures

Unrecognized MI was defined as cardiac MRI evidence of MI without a history of clinically evident MI. Recognized MI was defined as cardiac MRI evidence of MI with a history of clinically evident MI. Cerebral infarctions on brain MRI were included regardless of associated symptoms. Multiple logistic regression was used to evaluate the association between MI status (no MI, unrecognized MI, or recognized MI) and cerebral infarction after adjustment for demographic factors and vascular risk factors. In addition, we evaluated the association between unrecognized MI and embolic infarcts of undetermined source.

Results

Five enrolled participants had nondiagnostic brain MRI studies and were excluded. Among 925 participants, 480 (51.9%) were women; the mean (SD) age was 75.9 (5.3) years. There were 221 participants (23.9%) with cardiac MRI evidence of MI, of whom 68 had recognized MI and 153 unrecognized MI. There were 308 participants (33.3%) with brain MRI evidence of cerebral infarction; 93 (10.0%) had embolic infarcts of undetermined source. After adjustment for demographic factors and vascular risk factors, the likelihood (odds ratio) of having cerebral infarction was 2.0 (95% CI, 1.2-3.4; P = .01) for recognized MI and 1.5 (95% CI, 1.02-2.2; P = .04) for unrecognized MI. After adjustment for demographics and vascular risk factors, unrecognized MI was also associated with embolic infarcts of undetermined source (odds ratio, 2.0 [95% CI, 1.1-3.5]; P = .02).

Conclusions and Relevance

In a population-based sample, we found an association between unrecognized MI and cerebral infarction. These findings suggest that unrecognized MI may be a novel risk factor for cardiac embolism and cerebral infarction.

Association Between Ambient Air Pollution and Cardiac Morpho-Functional Phenotypes: Insights From the UK Biobank Population Imaging Study

Background

Exposure to ambient air pollution is strongly associated with increased cardiovascular morbidity and mortality. Little is known about the influence of air pollutants on cardiac structure and function. We aim to investigate the relationship between chronic past exposure to traffic-related pollutants and the cardiac chamber volume, ejection fraction, and left ventricular remodeling patterns after accounting for potential confounders.

Methods

Exposure to ambient air pollutants including particulate matter and nitrogen dioxide was estimated from the Land Use Regression models for the years between 2005 and 2010. Cardiac parameters were measured from cardiovascular magnetic resonance imaging studies of 3920 individuals free from pre-existing cardiovascular disease in the UK Biobank population study. The median (interquartile range) duration between the year of exposure estimate and the imaging visit was 5.2 (0.6) years. We fitted multivariable linear regression models to investigate the relationship between cardiac parameters and traffic-related pollutants after adjusting for various confounders.

Results

The studied cohort was 62±7 years old, and 46% were men. In fully adjusted models, particulate matter with an aerodynamic diameter <2.5 μm concentration was significantly associated with larger left ventricular end-diastolic volume and end-systolic volume (effect size = 0.82%, 95% CI, 0.09-1.55%, P=0.027; and effect size = 1.28%, 95% CI, 0.15-2.43%, P=0.027, respectively, per interquartile range increment in particulate matter with an aerodynamic diameter <2.5 μm) and right ventricular end-diastolic volume (effect size = 0.85%, 95% CI, 0.12-1.58%, P=0.023, per interquartile range increment in particulate matter with an aerodynamic diameter <2.5 μm). Likewise, higher nitrogen dioxide concentration was associated with larger biventricular volume. Distance from the major roads was the only metric associated with lower left ventricular mass (effect size = -0.74%, 95% CI, -1.3% to -0.18%, P=0.01, per interquartile range increment). Neither left and right atrial phenotypes nor left ventricular geometric remodeling patterns were influenced by the ambient pollutants.

Conclusions

In a large asymptomatic population with no prevalent cardiovascular disease, higher past exposure to particulate matter with an aerodynamic diameter <2.5 μm and nitrogen dioxide was associated with cardiac ventricular dilatation, a marker of adverse remodeling that often precedes heart failure development.

Small and large vessel disease in persons with unrecognized compared to recognized myocardial infarction: The Tromsø Study 2007-2008

BACKGROUND

Unrecognized myocardial infarction (MI) is a frequent condition with unknown underlying reason. We hypothesized the lack of recognition of MI is related to pathophysiology, specifically differences in underlying small and large vessel disease.

METHODS

6128 participants were examined with retinal photography, ultrasound of the carotid artery and a 12‑lead electrocardiography (ECG). Small vessel disease was defined as narrower retinal arterioles and/or wider retinal venules measured on retinal photographs. Large vessel disease was defined as carotid artery pathology. We defined unrecognized MI as ECG-evidence of MI without a clinically recognized event. We analyzed the cross-sectional relationship between MI recognition and markers of small and large vessel disease, adjusted for age and sex.

RESULTS

Unrecognized MI was present in 502 (8.2%) and recognized MI in 326 (5.3%) of the 6128 participants. Compared to recognized MI, unrecognized MI was associated with small vessel disease indicated by narrower retinal arterioles (OR 1.66, 95% CI 1.05-2.62, highest vs. lowest quartile). Unrecognized MI was less associated with wider retinal venules (OR 0.55, 95% CI 0.35-0.87, lowest vs. highest quartile). Compared to recognized MI, unrecognized MI was less associated with large vessel disease indicated by presence of plaque in the carotid artery (OR for presence of carotid artery plaque in unrecognized MI 0.51, 95% CI 0.37-0.69). No significant sex interaction was present.

CONCLUSIONS

Unrecognized MI was more associated with small vessel disease and less associated with large vessel disease compared to recognized MI. These findings suggest that the pathophysiology behind unrecognized and recognized MI may differ.

Unrecognized myocardial infarction detected on cardiac magnetic resonance imaging: Association with coronary artery calcium score and cardiovascular risk prediction scores in asymptomatic Asian cohort

Background

To investigate the association between unrecognized myocardial infarction (UMI) assessed with cardiac magnetic resonance (CMR) and coronary artery calcium (CAC) and cardiovascular risk prediction scores in asymptomatic Asian subjects.

Materials and methods

Total 872 asymptomatic subjects without prior cardiovascular event (male:female, 817:55; age, 53.88 ± 5.91) who underwent both CMR and CAC scoring CT were included. UMI were accessed and framingham risk score (FRS) and ASCVD (atherosclerotic cardiovascular disease) risk score by ACC/AHA were calculated.

Results

Late gadolinium enhancement indicating UMI was noted in 23 of 872 subjects (2.64%), but only three of them showed ECG abnormality (13.04%). Subjects with UMI showed higher CAC scores, FRS, and ASCVD scores than those without UMI (p < .001, p = .011 and p = .024, respectively). The prevalence of UMI differed significantly according to the CAC scores as follows: 1% in CAC = 0 (4/403), 1% in 1 ≤ CAC <100 (2/293), 6.1% in 100 ≤ CAC < 400 (7/114) and 14.5% in CAC ≥ 400 (9/62), respectively (p < .001). Receiver operating characteristics (ROC) analysis by using CAC score demonstrated an area under the curve (AUC) of 0.816 (95% confidence interval (CI), 0.780–0.848; p < .0001) for predicting UMI, which is superior to FRS [AUC, 0.712; 95% CI, 0.671–0.751; p = .009] and ASCVD risk score [AUC, 0.689; 95% CI, 0.648–0.729; p = .036].

Conclusion

The prevalence of UMI increases with increasing burden of CAC and FRS. CAC score is a good discriminator for UMI, superior to FRS and ASCVD score, in asymptomatic population.

[Management of acute coronary syndrome without ST-segment elevation]

Acute coronary syndrome without persistent ST-segment elevation (non-ST segment elevation myocardial infarction and instable angina pectoris NSTEMI-ACS) is common and is associated with a high mortality. In addition to 12-channel echocardiograph (ECG) assessment, measurement of cardiac troponins I and T are important for risk stratification and diagnosis. The introduction of high-sensitivity cardiac troponin assays and their implementation into clinical practice has influenced risk stratification and treatment of these patients. Additional diagnostic validation must supplement routine clinical chemistry testing following the initial measurement to distinguish between different possible causes of troponin elevation above the 99th percentile. The time point for the additional troponin measurement depends on the different protocols and troponin assays and is stipulated in the current guidelines. The use of both 1‑hour and 3‑hour protocols together with the clinical presentation and work-up of possible differential diagnoses provide optimal care of patients. Patients who test positive for troponin dynamics should undergo invasive diagnostics and treatment within 24 h of presentation and within 2 h is recommended for unstable patients. Clopidogrel is indicated only in patients requiring oral anticoagulation.

Pain Tolerance in Persons With Recognized and Unrecognized Myocardial Infarction: A Population-Based, Cross-Sectional Study

BACKGROUND

Unrecognized myocardial infarction (MI) is a prevalent condition associated with a similar risk of death as recognized MI. It is unknown why some persons experience MI with few or no symptoms; however, one possible explanation is attenuated pain sensitivity. To our knowledge, no previous study has examined the association between pain sensitivity and recognition of MI.

METHODS AND RESULTS

We conducted a population-based cross-sectional study with 4849 included participants who underwent the cold pressor test (a common experimental pain assay) and ECG. Unrecognized MI was present in 387 (8%) and recognized MI in 227 (4.7%) participants. Participants with unrecognized MI endured the cold pressor test significantly longer than participants with recognized MI (hazard ratio for aborting the cold pressor test, 0.64; CI, 0.47-0.88), adjusted for age and sex. The association was attenuated and borderline significant after multivariable adjustment. The association between unrecognized MI and lower pain sensitivity was stronger in women than in men, and statistically significant in women only, but interaction testing was not statistically significant (P for interaction=0.14).

CONCLUSIONS

Our findings suggest that persons who experience unrecognized MI have reduced pain sensitivity compared with persons who experience recognized MI. This may partially explain the lack of symptoms associated with unrecognized MI.

Prevalence and incidence of Q-wave unrecognized myocardial infarction in general population: Diagnostic value of the electrocardiogram. The REGICOR study

BACKGROUND

Diagnosis of unrecognized myocardial infarction (UMI) remains an open question in epidemiological and clinical studies, inhibiting effective secondary prevention of myocardial infarction. We aimed to determine the prevalence and incidence of Q-wave UMI in asymptomatic individuals aged 35 to 74years, and to ascertain the positive predictive value (PPV) of asymptomatic Q-wave to diagnose UMI.

METHODS

Two population-based cross-sectional studies were conducted, in 2000 (with 10-year follow-up) and in 2005. A baseline electrocardiogram was obtained for each participant. Imaging techniques (echocardiography, cardiac magnetic resonance imaging, and myocardial perfusion single-photon emission computerized tomography) were used to confirm UMI in patients with asymptomatic Q-wave.

RESULTS

The prevalence of confirmed Q-wave UMI in the 5580 participants was 0.18% (95% confidence interval [CI]: 0.10-0.33) and the incidence rate was 27.1 Q-wave UMI per 100,000person-years. The proportion of confirmed Q-wave UMI with respect to all prevalent MI was 8.1% (95% CI: 4.4-14.2). The PPV of asymptomatic Q-wave to diagnose Q-wave UMI was 29.2% (95% CI: 18.2-43.2%) overall, but much higher (75%, 95% CI: 40.9-92.9%) in participants with 10-year CHD risk ≥10%, compared to lower-risk participants.

CONCLUSION

Opportunistic identification of asymptomatic Q-waves by routine electrocardiogram overestimates actual Q-wave UMI, which represents 8% to 13% of all myocardial infarction in the population aged 35 to 74years. This overestimation is particularly high in the population at low cardiovascular risk. In epidemiological studies and in clinical practice, diagnosis of a pathologic Q-wave in asymptomatic patients requires detailed analysis of imaging tests to confirm or rule out myocardial necrosis.

Emerging roles of thioredoxin cycle enzymes in the central nervous system

The thioredoxins (Trxs) constitute a family of enzymes which catalyze the reduction of protein disulfide bonds. Recent animal studies have revealed the importance of the Trx superfamily in various experimental systems. For example, the homozygous disruption of the genes encoding cytoplasmic (TRX1) or mitochondrial Trx (TRX2) in mice generates lethal embryonic phenotypes. In contrast, transgenic mice overexpressing TRX1 show an extended life span and are relatively resistant to ischemia- mediated brain damage. In addition to their capacity to detoxify peroxides in concert with peroxiredoxins and Trx reductases, Trx isozymes perform multiple redox signaling functions mediated by their specific interaction with various proteins, including redox-regulated kinases and transcription factors. Recent studies indicate that specific isoforms of Trx cycle enzymes, targeted to different cell compartments, are key regulators of fundamental processes, such as gene expression, cell growth and apoptosis. The present review is primarily focused on the emerging neuroprotective role of these proteins in the central nervous system.