Sex differences in mental stress-induced myocardial ischemia in young survivors of an acute myocardial infarction

Neighborhood poverty and hemodynamic, neuroendocrine, and immune response to acute stress among patients with coronary artery disease

Living in neighborhoods characterized by poverty may act as a chronic stressor that results in physiological dysregulation of the sympathetic nervous system. No previous study has assessed neighborhood poverty with hemodynamic, neuroendocrine, and immune reactivity to stress. We used data from 632 patients with coronary artery disease. Patients' residential addresses were geocoded and merged with poverty data from the 2010 American Community Survey at the census-tract level. A z-transformation was calculated to classify census tracts (neighborhoods) as either having 'high' or 'low' poverty. Systolic blood pressure, diastolic blood pressure, heart rate, rate-pressure product, epinephrine, interleukin-6, and high-sensitivity C-reactive protein were measured before and after a public speaking stress task. Multilevel models were used for repeated measures and accounting for individuals nested within census tracts. Adjusted models included demographics, lifestyle and medical risk factors, and medication use. Another set of models included propensity scores weighted by the inverse probability of neighborhood status for sex, age, race, and individual-level income. The mean age was 63 years and 173 were women. After adjusting for potential confounders, participants living in high (vs. low) poverty neighborhoods had similar hemodynamic values at rest and lower values during mental stress for systolic blood pressure (157 mmHg vs. 161 mmHg; p = 0.07), heart rate (75 beats/min vs. 78 beats/min; p = 0.02) and rate-pressure product (11839 mmHg x beat/min vs 12579 mmHg x beat/min; p = 0.01). P-values for neighborhood poverty-by-time interactions were <0.05. Results were similar in the propensity weighted models. There were no significant differences in inflammatory and epinephrine responses to mental stress based on neighborhood poverty status. A blunted hemodynamic response to mental stress was observed among participants living in high poverty neighborhoods. Future studies should explore whether neighborhood poverty and blunted hemodynamic response to stress translate into differences in long-term cardiovascular outcomes.

Brain mechanisms of stress and depression in coronary artery disease

INTRODUCTION

Major depression is associated with an increased risk for and mortality from coronary artery disease (CAD), however the mechanisms by which this occurs are not clear. Depression, which is linked to stress, is associated with changes in brain areas involved in memory and the stress response, and it is likely that these regions play an important role in this increased risk. This study assessed the effects of stress on brain and cardiac function in patients with CAD with and without depression.

METHODS

CAD patients with (N = 17) and without (N = 21) major depression based on the Structured Clinical Interview for DSM-IV (DSM-IV) and/or a Hamilton Depression Scale score of nine or greater underwent imaging of the brain with high resolution positron emission tomography (HR-PET) and [O-15] water and imaging of the heart with single photon emission tomography (SPECT) and [Tc-99 m] sestamibi during mental stress (mental arithmetic) and control conditions.

RESULTS

Patients with CAD and major depression showed increased parietal cortex activation and a relative failure of medial prefrontal/anterior cingulate activation during mental stress compared to CAD patients without depression. Depressed CAD patients with stress-induced myocardial ischemia, however, when compared to depressed CAD patients without showed increased activation in rostral portions of the anterior cingulate.

CONCLUSIONS

These findings are consistent with a role for brain areas implicated in stress and depression in the mechanism of increased risk for CAD morbidity and mortality in CAD patients with the diagnosis of major depression.

A lay epidemiological study on coexistent stress in hypertension: Its prevalence, risk factors, and implications in patients' lives

Introduction:

Hypertension poses a global challenge in terms of morbidity and mortality. Worldwide prevalence of hypertension is over 40%. Management of hypertension targets blood pressure control to prevent disease complications. Though stress and hypertension are closely related, stress management is often overlooked in the treatment of hypertension.

Aims:

(1) To estimate the prevalence of stress in hypertensive patients and (2) to study the associated risk factors of stress and its implications in disease management.

Materials and Methods:

It was a hospital-based, cross-sectional study done in Western India for 1 year. Data were collected from 400 hypertensive patients attending the selected health institutions using a pretested questionnaire. Chi-square tests were done using Medcalc 10.4.8.0.

Results:

The prevalence of stress in hypertensive patients was found to be 84.3%. Only 2.4% of these patients sought help from any health professional for stress. The most common stressors found in the patients were financial dependence on others, living in rented house, having a daughter of marriageable age because of associated dowry, death of a loved one, sleep-related problem, and owing a debt among others. Significant statistical association (P < 0.05) of stress was observed with the type of family and socioeconomic status. A highly significant association (P < 0.001) of stress with religion and residential area (whether urban non-slum, slum, or rural) was observed. Stress in individuals leads to poorer compliance with treatment and blood pressure control.

Conclusion:

Coexistent stress should be diagnosed and managed in patients of hypertension for proper disease management and control.

Sex-Specific Association Between Coronary Artery Disease Severity and Myocardial Ischemia Induced by Mental Stress

OBJECTIVE

It is unclear whether mental stress-induced myocardial ischemia (MSIMI) is related to obstructive coronary artery disease (CAD). We examined this question and contrasted results with ischemia induced by conventional stress testing (CSIMI). Because women are more susceptible to ischemia without coronary obstruction than men, we examined sex differences.

METHODS

We studied 276 patients 61 years and younger with recent myocardial infarction. CAD severity was quantified using the log-transformed Gensini Score (lnGS) and the Sullivan Stenosis Score. Patients underwent myocardial perfusion imaging with mental stress (public speaking) and conventional (exercise or pharmacological) stress testing. MSIMI and CSIMI were defined as a new or worsening perfusion defect.

RESULTS

The prevalence of MSIMI was 15% in men and 20% in women. The median GS for patients with MSIMI was 65.0 in men and 28.5 in women. In logistic regression models adjusted for demographic and cardiovascular risk factors, CAD severity was associated with CSIMI in the full sample (odds ratio [OR] = 1.49, 95% [CI], 1.14-1.95, per 1-unit increase in lnGS), with no significant difference by sex. Although CAD severity was not associated with MSIMI in the entire sample, results differed by sex. CAD severity was associated with MSIMI among men (OR = 1.95, 95% CI, 1.13-3.36, per 1-unit increase in lnGS), but not among women (OR = 1.02, 95% CI, 0.74-1.42, p = .042 for interaction). Analysis using Sullivan Stenosis Score yielded similar results.

CONCLUSIONS

Findings suggest that CAD severity is related to MSIMI in men but not women. MSIMI in women may therefore be driven by alternative mechanisms such as coronary microvascular disease.

Gender differences in psychosocial outcomes of psychotherapy trial in patients with depression and coronary artery disease

INTRODUCTION

The biological and psychosocial risk profile differs between women and men with coronary artery disease (CAD). Depressive symptoms and Vital Exhaustion (VE) predict an unfavourable course of CAD. The secondary analysis of the SPIRR-CAD trial offered the possibility to examine gender as exposure variable of the clinical and psychological situation at baseline and in a variety of psychosocial measures as outcomes.

METHODS

In this trial, 450 men (78.9%) and 120 women (21.1%) with CAD (age ≤ 75 y), with mild to moderate depression (scoring ≥8 on the HADS), were randomized to usual care with or without a stepwise psychotherapy intervention. Beside clinical measures exhaustion and other indicators of depressive symptoms were collected at baseline and 18-month follow up.

RESULTS

Men had more signs and symptoms of heart disease at baseline, whereas women had higher psychosocial burden (e.g. negative affect). Women were more likely to live alone, had lower educational levels and employment rates and higher levels of depression and exhaustion. The psychotherapy intervention differed as a function of gender: In women, VE decreased from 29.4 ± 8.1 to 22.1 ± 11.7 in the intervention group (IG) and from 29.2 ± 8.2 to 25.1 ± 11.3 in the control group (CG). In men VE decreased from 23.3 + -10.8 to 21.2 ± 9.7 in the IG and from 23.6 ± 10.7 to 19.3 ± 11.3 in the CG (time x intervention x gender; F = 4.97; p = .026).

DISCUSSION

Women had a higher psychosocial burden than men. VE compared to other rating instruments of depressive symptoms suggested a stronger response to the intervention in women. VE may help to understand gender differences in psychotherapeutic treatment studies of CAD.

ISRCTN

76240576; clinicaltrials.gov.

Gender-Based Differences in Anxiety and Depression Following Acute Myocardial Infarction

Background

Among patients with heart disease, depression and anxiety disorders are highly prevalent and persistent. Both depression and anxiety play a significant role in cardiovascular disease progression and are acknowledged to be independent risk factors. However, there is very little gender-related analysis concerning cardiovascular diseases and emotional disorders.

Objective

We aimed to evaluate depression and anxiety levels in patients suffering from myocardial infarction [MI] within the first month after the MI and to assess the association between cardiovascular disease risk factors, demographic indicators and emotional disorders, as well as to determine whether there are gender-based differences or similarities.

Methods

This survey included demographic questions, clinical characteristics, questions about cardiovascular disease risk factors and the use of the Hospital Anxiety and Depression Scale [HADS]. All statistical tests were two-sided, and p values < 0.05 were considered statistically significant.

Results

It was determined that 71.4% of female and 60.4% of male patients had concomitant anxiety and/or depression symptomatology (p = 0.006). Using men as the reference point, women had an elevated risk of having some type of psychiatric disorder (odds ratio, 2.86, p = 0.007). The HADS-D score was notably higher in women (8.66 ± 3.717) than men (6.87 ± 4.531, p = 0.004). It was determined that male patients who developed depression were on average younger than those without depression (p = 0.005).

Conclusions

Women demonstrated an elevated risk of having anxiety and/or depression disorder compared to men. Furthermore, depression severity increased with age in men, while anxiety severity decreased. In contrast, depression and anxiety severity was similar for women of all ages after the MI. A higher depression score was associated with diabetes and physical inactivity, whereas a higher anxiety score was associated with smoking in men. Hypercholesterolemia was associated with both higher anxiety and depression scores, and a higher depression score was associated with physical inactivity in women.

Telephone-based mindfulness training to reduce stress in women with myocardial infarction: Rationale and design of a multicenter randomized controlled trial

BACKGROUND

Elevated stress is associated with adverse cardiovascular disease outcomes and accounts in part for the poorer recovery experienced by women compared with men after myocardial infarction (MI). Psychosocial interventions improve outcomes overall but are less effective for women than for men with MI, suggesting the need for different approaches. Mindfulness-based cognitive therapy (MBCT) is an evidence-based intervention that targets key psychosocial vulnerabilities in women including rumination (i.e., repetitive negative thinking) and low social support. This article describes the rationale and design of a multicenter randomized controlled trial to test the effects of telephone-delivered MBCT (MBCT-T) in women with MI.

METHODS

We plan to randomize 144 women reporting elevated perceived stress at least two months after MI to MBCT-T or enhanced usual care (EUC), which each involve eight weekly telephone sessions. Perceived stress and a set of patient-centered health outcomes and potential mediators will be assessed before and after the 8-week telephone programs and at 6-month follow-up. We will test the hypothesis that MBCT-T will be associated with greater 6-month improvements in perceived stress (primary outcome), disease-specific health status, quality of life, depression and anxiety symptoms, and actigraphy-based sleep quality (secondary outcomes) compared with EUC. Changes in mindfulness, rumination and perceived social support will be evaluated as potential mediators in exploratory analyses.

CONCLUSIONS

If found to be effective, this innovative, scalable intervention may be a promising secondary prevention strategy for women with MI experiencing elevated perceived stress.

Mental Stress-Induced-Myocardial Ischemia in Young Patients With Recent Myocardial Infarction: Sex Differences and Mechanisms

BACKGROUND

Mental stress-induced myocardial ischemia (MSIMI) is frequent in patients with coronary artery disease and is associated with worse prognosis. Young women with a previous myocardial infarction (MI), a group with unexplained higher mortality than men of comparable age, have shown elevated rates of MSIMI, but the mechanisms are unknown.

METHODS

We studied 306 patients (150 women and 156 men) ≤61 years of age who were hospitalized for MI in the previous 8 months and 112 community controls (58 women and 54 men) frequency matched for sex and age to the patients with MI. Endothelium-dependent flow-mediated dilation and microvascular reactivity (reactive hyperemia index) were measured at rest and 30 minutes after mental stress. The digital vasomotor response to mental stress was assessed using peripheral arterial tonometry. Patients received 99mTc-sestamibi myocardial perfusion imaging at rest, with mental (speech task) and conventional (exercise/pharmacological) stress.

RESULTS

The mean age of the sample was 50 years (range, 22-61). In the MI group but not among controls, women had a more adverse socioeconomic and psychosocial profile than men. There were no sex differences in cardiovascular risk factors, and among patients with MI, clinical severity tended to be lower in women. Women in both groups showed a higher peripheral arterial tonometry ratio during mental stress but a lower reactive hyperemia index after mental stress, indicating enhanced microvascular dysfunction after stress. There were no sex differences in flow-mediated dilation changes with mental stress. The rate of MSIMI was twice as high in women as in men (22% versus 11%, P=0.009), and ischemia with conventional stress was similarly elevated (31% versus 16%, P=0.002). Psychosocial and clinical risk factors did not explain sex differences in inducible ischemia. Although vascular responses to mental stress (peripheral arterial tonometry ratio and reactive hyperemia index) also did not explain sex differences in MSIMI, they were predictive of MSIMI in women only.

CONCLUSIONS

Young women after MI have a 2-fold likelihood of developing MSIMI compared with men and a similar increase in conventional stress ischemia. Microvascular dysfunction and peripheral vasoconstriction with mental stress are implicated in MSIMI among women but not among men, perhaps reflecting women's proclivity toward ischemia because of microcirculatory abnormalities.

Mental stress peripheral vascular reactivity is elevated in women with coronary vascular dysfunction: Results from the NHLBI-sponsored Cardiac Autonomic Nervous System (CANS) study

BACKGROUND

Women with chest pain, ischemia, and no obstructive coronary artery disease often have coronary vascular dysfunction (CVaD). Peripheral vascular reactivity to mental stress may contribute mechanistic understanding of stress-induced ischemia in women with CVaD.

METHODS

62 women (41 CVaD and 21 controls) underwent mental stress testing (MST) with anger recall, mental arithmetic, and forehead cold pressor (COP) challenge. Emotional arousal was measured (Likert scale). Reactive hyperemia index (RHI) was calculated before and after MST by peripheral arterial tonometry (PAT). Stress PAT ratio (SPR) of pulse amplitude during stress to rest was obtained to measure vasoconstriction. Wilcoxson rank sum test was used for analysis.

RESULTS

Mean age of CVaD and control groups was 58±9 and 55±10years (p=0.73). Baseline RHI correlated with coronary endothelial function (r=0.36, p=0.03) and inversely with RHI change post-MST (r=-0.51, p<0.001). During MST, 10% of controls reported chest pain vs. 41% of CVaD subjects (p=0.01). RHI did not change significantly after MST in either group. CVaD subjects had lower SPR vs. controls during mental arithmetic (0.54 [0.15, 1.46] vs. 0.67 [0.36, 1.8], p=0.039), not evident in the other tasks. Vasoconstriction inversely correlated with anxiety (r=-3.4, p=0.03), frustration (r=-0.37, p=0.02), and feeling challenged (r=-0.37, p=0.02) in CVaD but not controls.

CONCLUSIONS

Mental stress peripheral vascular reactivity is elevated in women with CVaD compared to controls. Elevated vascular reactivity may be one contributor to stress-induced chest pain in CVaD. Interventions that modulate vasoconstrictive responses may be of benefit and should be tested in clinical trials in women with CVaD.

Sex Differences in Hemodynamic and Microvascular Mechanisms of Myocardial Ischemia Induced by Mental Stress

OBJECTIVE

To investigate sex-specific vascular mechanisms for mental stress-induced myocardial ischemia (MSIMI).

APPROACH AND RESULTS

Baseline data from a prospective cohort study of 678 patients with coronary artery disease underwent myocardial perfusion imaging before and during a public speaking stressor. The rate-pressure product response was calculated as the difference between the maximum value during the speech minus the minimum value during rest. Peripheral vasoconstriction by peripheral arterial tonometry was calculated as the ratio of pulse wave amplitude during the speech over the resting baseline; ratios <1 indicate a vasoconstrictive response. MSIMI was defined as percent of left ventricle that was ischemic and as a dichotomous variable. Men (but not women) with MSIMI had a higher rate-pressure product response than those without MSIMI (6500 versus 4800 mm Hg bpm), whereas women (but not men) with MSIMI had a significantly lower peripheral arterial tonometry ratio than those without MSIMI (0.5 versus 0.8). In adjusted linear regression, each 1000-U increase in rate-pressure product response was associated with 0.32% (95% confidence interval, 0.22-0.42) increase in inducible ischemia among men, whereas each 0.10-U decrease in peripheral arterial tonometry ratio was associated with 0.23% (95% confidence interval, 0.11-0.35) increase in inducible myocardial ischemia among women. Results were independent of conventional stress-induced myocardial ischemia.

CONCLUSIONS

Women and men have distinct cardiovascular reactivity mechanisms for MSIMI. For women, stress-induced peripheral vasoconstriction with mental stress, and not increased hemodynamic workload, is associated with MSIMI, whereas for men, it is the opposite. Future studies should examine these pathways on long-term outcomes.

Self-management of cardiac pain in women: an evidence map

OBJECTIVE

To describe the current evidence related to the self-management of cardiac pain in women using the process and methodology of evidence mapping.

DESIGN AND SETTING

Literature search for studies that describe the self-management of cardiac pain in women greater than 18 years of age, managed in community, primary care or outpatient settings, published in English or a Scandinavian language between 1 January 1990 and 24 June 2016 using AMED, CINAHL, ERIC, EMBASE, MEDLINE, Proquest, PsychInfo, the Cochrane Library, Scopus, Swemed+, Web of Science, the Clinical Trials Registry, International Register of Controlled Trials, MetaRegister of Controlled Trials, theses and dissertations, published conference abstracts and relevant websites using GreyNet International, ISI proceedings, BIOSIS and Conference papers index. Two independent reviewers screened using predefined eligibility criteria. Included articles were classified according to study design, pain category, publication year, sample size, per cent women and mean age.

INTERVENTIONS

Self-management interventions for cardiac pain or non-intervention studies that described views and perspectives of women who self-managed cardiac pain.

PRIMARY AND SECONDARY OUTCOMES MEASURES

Outcomes included those related to knowledge, self-efficacy, function and health-related quality of life.

RESULTS

The literature search identified 5940 unique articles, of which 220 were included in the evidence map. Only 22% (n=49) were intervention studies. Sixty-nine per cent (n=151) of the studies described cardiac pain related to obstructive coronary artery disease (CAD), 2% (n=5) non-obstructive CAD and 15% (n=34) postpercutaneous coronary intervention/cardiac surgery. Most were published after 2000, the median sample size was 90 with 25%-100% women and the mean age was 63 years.

CONCLUSIONS

Our evidence map suggests that while much is known about the differing presentations of obstructive cardiac pain in middle-aged women, little research focused on young and old women, non-obstructive cardiac pain or self-management interventions to assist women to manage cardiac pain.

PROSPERO REGISTRATION NUMBER

CRD42016042806.

The association between acute mental stress and abnormal left atrial electrophysiology

BACKGROUND

Acute stress may trigger atrial fibrillation (AF), but the underlying mechanisms are unclear. We examined if acute mental stress results in abnormal left atrial electrophysiology as detected by more negative deflection of P-wave terminal force in lead V₁ (PTFV₁ ), a well-known marker of AF risk.

METHODS AND RESULTS

We examined this hypothesis in 422 patients (mean age = 56 ± 10 years; 61% men; 44% white) with stable coronary heart disease who underwent mental (speech task) stress testing. PTFV₁ was defined as the duration (milliseconds) times the value of the depth (μV) of the downward deflection (terminal portion) of the P-wave in lead V₁ measured on digital electrocardiograms (ECG). Electrocardiographic left atrial abnormality was defined as PTFV₁ ≤ -4000 μV*ms. Mean PTFV₁ values during stress and recovery were compared with rest. The percentage of participants who developed left atrial abnormality during stress and recovery was compared with the percentage at rest. Compared with rest, PTFV₁ became more negative during mental stress (mean change =  -348, 95% CI = [-515, -182]; P < 0.001) and no change was observed at recovery (mean change = 12, 95%CI = [-148, 172]; P = 0.89). A larger percentage of participants showed left atrial abnormality on ECGs obtained at stress (n = 163, 39%) and recovery (n = 142, 34%) compared with rest (n = 127, 30%).

CONCLUSION

Acute mental stress alters left atrial electrophysiology, suggesting that stressful situations promote adverse transient electrical changes to provide the necessary substrate for AF.

Common Variants of Vitamin D Receptor Gene Polymorphisms and Susceptibility to Coronary Artery Disease: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

ApaI, FokI, TaqI, and BsmI polymorphisms in the vitamin D receptor (VDR) gene have been reported to be associated with the risk of coronary artery disease (CAD), although the results of previous studies have been inconsistent. The aim of this study was to explore whether these polymorphisms play a role in the genetic susceptibility to CAD.

METHODS

A comprehensive search of Medline and Embase databases was conducted for studies evaluating the association between the VDR polymorphisms and CAD risk. Odds ratios with 95% confidence intervals were calculated to assess the strength of association in the dominant model, recessive model, allelic model, and genotypes contrast.

RESULTS

Nine studies involving a total of 5,259 cases and 1,981 controls were finally included in this meta-analysis. Overall, no significant associations were found between ApaI, FokI, TaqI, and BsmI polymorphisms and the risk of CAD in any of the genetic models (all p ˃ 0.05). Moreover, a subgroup analysis by ethnicity did not reveal a significant relationship between any of the examined polymorphisms and CAD risk in Caucasians and East-Asians for any model (all p ˃ 0.05).

CONCLUSION

Current evidence suggests that the ApaI, FokI, TaqI, and BsmI polymorphisms of the VDR gene might not be associated with genetic susceptibility to CAD. Further well-designed studies with large sample sizes are needed to confirm our results.

Anxiety and anger immediately prior to myocardial infarction and long-term mortality: Characteristics of high-risk patients

OBJECTIVE

Acute high levels of anger and anxiety are associated with an elevated risk of myocardial infarction (MI) in the following two hours. MIs preceded by these acute negative emotions may also have a poor long-term prognosis, but information about high-risk patients is lacking. We examined whether young age and female sex are associated with MIs that are preceded by negative emotions and whether age and sex moderate the subsequent increased mortality risk following MI preceded by negative emotions.

METHODS

We conducted a secondary analysis of the Determinants of Myocardial Infarction Onset Study (N=2176, mean age=60.1±12.3years, 29.2% women). Anxiety and anger immediately prior to (0-2h) MI and the day before (24-26h) MI were assessed using a structured interview. Subsequent 10-year all-cause mortality was determined using the US National Death Index.

RESULTS

Anxiety during the 0-2h pre-MI period was associated with younger age (OR=0.98,95% CI=0.96-0.99 per year) and female sex (OR=1.50,95% CI=1.11-2.02). Anger in the 0-2h pre-MI period was also associated with younger age (OR=0.95,95% CI=0.94-0.96) but not with sex (OR=0.93,95% CI=0.67-1.28). During follow-up, 580 (26.7%) patients died. Mortality rate was higher if MI occurred immediately after high anxiety, particularly in patients ≥65years (HR=1.80,95% CI=1.28-2.54) vs. younger patients (HR=0.87,95% CI=0.55-1.40; p-interaction=0.015). Other interactions with sex or anger were not significant.

CONCLUSIONS

Patients with high anxiety or anger levels in the critical 2-hour period prior to MI are younger than those without such emotional precipitants. In addition, pre-MI anxiety is associated with an elevated 10-year mortality risk in patients aged ≥65years.

Gender Differences in Radiation Dose From Nuclear Cardiology Studies Across the World: Findings From the INCAPS Registry

OBJECTIVES

The aim of this study was to investigate gender-based differences in nuclear cardiology practice globally, with a particular focus on laboratory volume, radiation dose, protocols, and best practices.

BACKGROUND

It is unclear whether gender-based differences exist in radiation exposure for nuclear cardiology procedures.

METHODS

In a large, multicenter, observational, cross-sectional study encompassing 7,911 patients in 65 countries, radiation effective dose was estimated for each examination. Patient-level best practices relating to radiation exposure were compared between genders. Analysis of covariance was used to determine any difference in radiation exposure according to gender, region, and the interaction between gender and region. Linear, logistic, and hierarchical regression models were developed to evaluate gender-based differences in radiation exposure and laboratory adherence to best practices. The study also included the United Nations Gender Inequality Index and Human Development Index as covariates in multivariable models.

RESULTS

The proportion of myocardial perfusion imaging studies performed in women varied among countries; however, there was no significant correlation with the Gender Inequality Index. Globally, mean effective dose for nuclear cardiology procedures was only slightly lower in women (9.6 ± 4.5 mSv) than in men (10.3 ± 4.5 mSv; p < 0.001), with a difference of only 0.3 mSv in a multivariable model adjusting for patients' age and weight. Stress-only imaging was performed more frequently in women (12.5% vs. 8.4%; p < 0.001); however, camera-based dose reduction strategies were used less frequently in women (58.6% vs. 65.5%; p < 0.001).

CONCLUSIONS

Despite significant worldwide variation in best practice use and radiation doses from nuclear cardiology procedures, only small differences were observed between genders worldwide. Regional variations noted in myocardial perfusion imaging use and radiation dose offer potential opportunities to address gender-related differences in delivery of nuclear cardiology care.

Perceived Stress After Acute Myocardial Infarction: A Comparison Between Young and Middle-Aged Women Versus Men

OBJECTIVE

The aim of the study was to examine how psychological stress changes over time in young and middle-aged patients after experiencing an acute myocardial infarction (AMI) and whether these changes differ between men and women.

METHODS

We analyzed data obtained from 2358 women and 1151 men aged 18 to 55 years hospitalized for AMI. Psychological stress was measured using the 14-item Perceived Stress Scale (PSS-14) at initial hospitalization and at 1 month and 12 months after AMI. We used linear mixed-effects models to examine changes in PSS-14 scores over time and sex differences in these changes, while adjusting for patient characteristics and accounting for correlation among repeated observations within patients.

RESULTS

Overall, patients' perceived stress decreased over time, especially during the first month after AMI. Women had higher levels of perceived stress than men throughout the 12-month period (difference in PSS-14 score = 3.63, 95% confidence interval = 3.08 to 4.18, p < .001), but they did not differ in how stress changed over time. Adjustment for patient characteristics did not alter the overall pattern of sex difference in changes of perceived stress over time other than attenuating the magnitude of sex difference in PSS-14 score (difference between women and men = 1.74, 95% confidence interval = 1.32 to 2.16, p < .001). The magnitude of sex differences in perceived stress was similar in patients with versus without post-AMI angina, even though patients with angina experienced less improvement in PSS-14 score than those without angina.

CONCLUSIONS

In young and middle-aged patients with AMI, women reported higher levels of perceived stress than men throughout the first 12 months of recovery. However, women and men had a similar pattern in how perceived stress changed over time.

Do Women With Anxiety or Depression Have Higher Rates of Myocardial Ischemia During Exercise Testing Than Men?

BACKGROUND

Women diagnosed with coronary artery disease (CAD) typically experience worse outcomes relative to men, possibly through diagnosis and treatment delays. Reasons for these delays may be influenced by mood and anxiety disorders, which are more prevalent in women and have symptoms (eg, palpitations and fatigue) that may be confounded with CAD. Our study examined sex differences in the association between mood and anxiety disorders and myocardial ischemia in patients with and without a CAD history presenting for exercise stress tests.

METHODS AND RESULTS

A total of 2342 patients (women n=760) completed a single photon emission computed tomographic exercise stress test (standard Bruce Protocol) and underwent a psychiatric interview (The Primary Care Evaluation of Mental Disorders) to assess mood and anxiety disorders. Ischemia was assessed using single photon emission computed tomography, with odds ratio used to calculate the effect of sex and mood/anxiety on the presence of ischemia during stress testing by CAD history in a stratified analyses, adjusted for relevant covariates. There was a sex by anxiety interaction with ischemia in those without a CAD history (P=0.015): women with anxiety were more likely to exhibit ischemia during exercise than women without anxiety (odds ratio, 1.75; 95% confidence interval, 1.05-2.89). No significant effects were observed for men nor mood.

CONCLUSIONS

Women with anxiety and no CAD history had higher rates of ischemia than women without anxiety. Results suggest that anxiety symptoms, many of which overlap with those of CAD, might mask CAD symptoms among women (but not men) and contribute to referral and diagnostic delays. Further research is needed to confirm this hypothesis.

Sex Differences in Mental Stress-Induced Myocardial Ischemia in Patients With Coronary Heart Disease

BACKGROUND

Emerging data suggest that young women with coronary heart disease (CHD) are disproportionally vulnerable to the adverse cardiovascular effects of psychological stress. We hypothesized that younger, but not older, women with stable CHD are more likely than their male peers to develop mental stress-induced myocardial ischemia (MSIMI).

METHODS AND RESULTS

We studied 686 patients (191 women) with stable coronary heart disease (CHD). Patients underwent (99m)Tc-sestamibi myocardial perfusion imaging at rest and with both mental (speech task) and conventional (exercise/pharmacological) stress testing. We compared quantitative (by automated software) and visual parameters of inducible ischemia between women and men and assessed age as an effect modifier. Women had a more-adverse psychosocial profile than men whereas there were few differences in medical history and CHD risk factors. Both quantitative and visual indicators of ischemia with mental stress were disproportionally larger in younger women. For each 10 years of decreasing age, the total reversibility severity score with mental stress was 9.6 incremental points higher (interaction, P<0.001) and the incidence of MSIMI was 82.6% higher (interaction, P=0.004) in women than in men. Incidence of MSIMI in women ≤50 years was almost 4-fold higher than in men of similar age and older patients. These results persisted when adjusting for sociodemographic and medical risk factors, psychosocial factors, and medications. There were no significant sex differences in inducible ischemia with conventional stress.

CONCLUSIONS

Young women with stable CHD are susceptible to MSIMI, which could play a role in the prognosis of this group.

Behavioral, emotional and neurobiological determinants of coronary heart disease risk in women

Women have more of the stress-related behavioral profile that has been linked to cardiovascular disease than men. For example, women double the rates of stress-related mental disorders such as depression and posttraumatic stress disorder (PTSD) than men, and have higher rates of exposure to adversity early in life. This profile may increase women's long-term risk of cardiometabolic conditions linked to stress, especially coronary heart disease (CHD). In addition to having a higher prevalence of psychosocial stressors, women may be more vulnerable to the adverse effects of these stressors on CHD, perhaps through altered neurobiological physiology. Emerging data suggest that young women are disproportionally susceptible to the adverse effects of stress on the risk of cardiovascular disease, both in terms of initiating the disease as well as worsening the prognosis in women who have already exhibited symptoms of the disease. Women's potential vulnerability to psychosocial stress could also help explain their higher propensity toward abnormal coronary vasomotion and microvascular disease compared with men.

Emotional triggering of cardiac dysfunction: the present and future

Mental stress and emotional arousal can act as triggers of acute myocardial infarction and other adverse cardiovascular outcomes. Experimental research examining mechanisms of the adverse interplay between mind and heart has led to the discovery of mental stress-induced cardiac dysfunction or myocardial ischemia (MSIMI). Evidence about the prevalence, clinical significance, and mechanistic bases of MSIMI outlines a wide range of central and peripheral bio-pathologic processes that are associated with emotions and behaviors. MSIMI is recognized as an integrated and intermediate biomarker underpinning the negative mind-heart interplay. Particularly, MSIMI research paves the way toward investigations aiming more specifically at recognizing the susceptibilities of individuals who are prone to respond adversely to the psycho-social-environmental stress. This article reviews recent literature on MSIMI research following the comprehensive review of Strike and Steptoe Eur Heart J 24:690-703, 2003. Further, this article outlines the main steps in the identification of the specific bio-pathologic manifestations of the cardiovascular system to emotional stress. Finally, a speculative description is provided of future directions in better searching for areas that may be critical targets in resolving adverse mind-heart interplays.

Cardiac function associated with previous, current and repeated depression and anxiety symptoms in a healthy population: the HUNT study

OBJECTIVE

Symptoms of anxiety and depression often co-exist with cardiovascular disease (CVD), yet little is known about the association with left ventricular (LV) subclinical dysfunction. We aimed to study the cross-sectional associations of previous, current and repeated depression or anxiety symptoms, with sensitive indices of LV systolic and diastolic function, based on tissue Doppler (TD) and speckle tracking (ST) imaging methods.

METHODS

A random selection of 1296 individuals free from known CVD, hypertension and diabetes were examined with echocardiography at baseline of the third Nord-Trøndelag Health Study, (HUNT3, 2006-2008). The primary outcomes were LV diastolic function (e') and LV systolic function (longitudinal global strain). The primary exposures were self-report on the Hospital Anxiety and Depression Scale (HADS). Associations between outcomes and baseline exposures were available for 1034 (80%), and with previous and repeated exposures for 700 participants who also participated in HUNT2 (1995-1997).

RESULTS

Previous and repeated depression symptoms, but not current depression, were linearly associated with a reduction in e'. The average sum of two repeated HADS-D scores 10 years apart had the strongest effect on e' (-8.3%; 95% CI -13.9% to -2.7%) per 5 units. We observed a sex difference between depression symptoms and longitudinal global strain (p for interaction 0.019), where women had a marginal negative effect. Anxiety symptoms, neither previous, current nor repeated were associated with subclinical LV dysfunction.

CONCLUSIONS

In a healthy sample, confirmed free of CVD, past and repeated depression symptoms were associated with subclinical LV dysfunction. Thus, depression symptoms might represent a modifiable risk factor for future CVD.

Acute Myocardial Infarction in Women: A Scientific Statement From the American Heart Association

Cardiovascular disease is the leading cause of mortality in American women. Since 1984, the annual cardiovascular disease mortality rate has remained greater for women than men; however, over the last decade, there have been marked reductions in cardiovascular disease mortality in women. The dramatic decline in mortality rates for women is attributed partly to an increase in awareness, a greater focus on women and cardiovascular disease risk, and the increased application of evidence-based treatments for established coronary heart disease. This is the first scientific statement from the American Heart Association on acute myocardial infarction in women. Sex-specific differences exist in the presentation, pathophysiological mechanisms, and outcomes in patients with acute myocardial infarction. This statement provides a comprehensive review of the current evidence of the clinical presentation, pathophysiology, treatment, and outcomes of women with acute myocardial infarction.

Young women post-MI have higher plasma concentrations of interleukin-6 before and after stress testing

OBJECTIVES

Young women have poorer prognosis after myocardial infarction (MI) and a higher rate of mental stress-induced ischemia compared with similarly aged men. A higher inflammatory status may help explain these sex differences.

METHODS

We examined 98 patients (49 women and 49 men) age 18-59years with recent MI (past 6months). Women and men were matched for age, type of MI, and time since MI. Interleukin 6 (IL-6) concentrations were measured at baseline, after mental stress using a speech task, and after exercise/pharmacologic stress (60 and 90min). Depressive symptoms were measured with the Beck Depression Inventory (BDI-II) and angiographic coronary artery disease (CAD) severity was quantified with the Gensini score. Single-photon emission computed tomography (SPECT) was used to obtain a computerized measurement of stress-induced ischemia (summed difference score, or SDS) and determine whether severity of stress-induced ischemia affects the inflammatory response to stress. Analysis was stratified by the median age of 50. Geometric mean concentrations of IL-6 were obtained from general linear regression models.

RESULTS

In both age groups, women had less angiographic CAD and a similar level of conventional risk factors compared with men. Despite this, baseline IL-6 geometric means before both mental and physical stress were twice as high in women ⩽50years of age compared to age-matched men (3.8 vs. 1.8pg/mL, p=0.001, across both conditions), while they were similar in women and men age >50years (2.3 vs. 2.2pg/mL, p=0.83). After mental stress, IL-6 concentrations increased in both women and men in a similar fashion and remained twice as high in women ⩽50years than men at both 60min (5.4 vs. 2.6pg/mL, p=0.002) and 90min (5.9 vs. 3.4pg/mL, p=0.01). No significant difference was found between women and men >50years of age at any time point after mental stress. Results were similar for physical stress. After accounting for SDS, IL-6 concentrations in young women remained higher after both mental and physical stress. Baseline IL-6 concentrations were not significantly related to inducible ischemia.

CONCLUSIONS

After MI, young women aged 50years or younger, compared with age-matched men, have remarkably higher concentrations of inflammation at baseline and after both mental and physical stress, with a similar inflammatory response to both stressors. Sustained concentrations of inflammation in young women, not their response to stress, may contribute to their adverse outcomes post-MI.

Sex differences in the pathophysiology, treatment, and outcomes in IHD

Heart disease is the number one killer of women. Although there are many similarities between men and women, the evolving understanding of ischemic heart disease in women allow us to emphasize the important differences that need to be recognized. These differences, including symptoms at presentation, importance of particular risk factors, pathophysiology of disease, and treatments/outcomes, will be discussed in this review.

Coronary Heart Disease Mortality Declines in the United States From 1979 Through 2011: Evidence for Stagnation in Young Adults, Especially Women

BACKGROUND

Coronary heart disease (CHD) mortality rates have fallen dramatically over the past 4 decades in the Western world. However, recent data from the United States and elsewhere suggest a plateauing of CHD incidence and mortality among young women. We therefore examined recent trends in CHD mortality rates in the United States according to age and sex.

METHODS AND RESULTS

We analyzed mortality data between 1979 and 2011 for US adults ≥25 years of age. We calculated age-specific CHD mortality rates and compared estimated annual percentage changes during 3 approximate decades of data (1979-1989, 1990-1999, and 2000-2011). We then used Joinpoint regression modeling to assess changes in trends over time on the basis of inflection points of the mortality rates. Adults ≥65 years of age showed consistent mortality declines, which became even steeper after 2000 (women, -5.0%; men, -4.4%). In contrast, young men and women (<55 years of age) initially showed a clear decline in CHD mortality from 1979 until 1989 (estimated annual percentage change, -5.5% in men and -4.6% in women). However, the 2 subsequent decades saw stagnation with minimal improvement. Notably, young women demonstrated no improvements between 1990 and 1999 (estimated annual percentage change, 0.1%) and only -1% estimated annual percentage change since 2000. Joinpoint analyses provided consistent results.

CONCLUSIONS

The dramatic decline in CHD mortality since 1979 conceals major heterogeneities. CHD death rates in older groups are now falling steeply. However, young adults have experienced frustratingly small decreases in CHD mortality rates since 1990. The drivers of these major differences in CHD mortality trends by age and sex merit urgent study.

Systematic Review and Individual Patient Data Meta-Analysis of Sex Differences in Depression and Prognosis in Persons With Myocardial Infarction: A MINDMAPS Study

OBJECTIVE

Using combined individual patient data from prospective studies, we explored sex differences in depression and prognosis post-myocardial infarction (MI) and determined whether disease indices could account for found differences.

METHODS

Individual patient data analysis of 10,175 MI patients who completed diagnostic interviews or depression questionnaires from 16 prospective studies from the MINDMAPS study was conducted. Multilevel logistic and Cox regression models were used to determine sex differences in prevalence of depression and sex-specific effects of depression on subsequent outcomes.

RESULTS

Combined interview and questionnaire data from observational studies showed that 36% (635/1760) of women and 29% (1575/5526) of men reported elevated levels of depression (age-adjusted odds ratio = 0.68, 95% confidence interval [CI] = 0.60-0.77). The risk for all-cause mortality associated with depression was higher in men (hazard ratio = 1.38, 95% CI = 1.30-1.47) than in women (hazard ratio = 1.22, 95% CI = 1.14-1.31; sex by depression interaction: p < .001). Low left ventricular ejection fraction (LVEF) was associated with higher depression scores in men only (sex by LVEF interaction: B = 0.294, 95% CI = 0.090-0.498), which attenuated the sex difference in the association between depression and prognosis.

CONCLUSIONS

The prevalence of depression post-MI was higher in women than in men, but the association between depression and cardiac prognosis was worse for men. LVEF was associated with depression in men only and accounted for the increased risk of all-cause mortality in depressed men versus women, suggesting that depression in men post-MI may, in part, reflect cardiovascular disease severity.

Angina and mental stress-induced myocardial ischemia

OBJECTIVE

Mental stress-induced myocardial ischemia is a common phenomenon in patients with coronary artery disease (CAD) and an emerging prognostic factor. Mental stress ischemia is correlated with ambulatory ischemia. However, whether it is related to angina symptoms during daily life has not been examined.

METHODS

We assessed angina frequency (past month) in 98 post-myocardial infarction (MI) subjects (age 18-60 years) using the Seattle Angina Questionnaire. Patients underwent [(99m)Tc]sestamibi SPECT perfusion imaging at rest, after mental stress, and after exercise/pharmacological stress. Summed scores of perfusion abnormalities were obtained by observer-independent software. A summed difference score (SDS), the difference between stress and rest scores, was used to quantify myocardial ischemia under both stress conditions.

RESULTS

The mean age was 50 years, 50% were female and 60% were non-white. After adjustment for age, sex, smoking, CAD severity, depressive, anger, and anxiety symptoms, each 1-point increase in mental stress-SDS was associated with 1.73-unit increase in the angina frequency score (95% CI: 0.09-3.37) and 17% higher odds of being in a higher angina frequency category (OR: 1.17, 95% CI: 1.00-1.38). Depressive symptoms were associated with 12% higher odds of being in a higher angina frequency category (OR: 1.12, 95% CI: 1.03-1.21). In contrast, exercise/pharmacological stress-induced SDS was not associated with angina frequency.

CONCLUSION

Among young and middle-aged post-MI patients, myocardial ischemia induced by mental stress in the lab, but not by exercise/pharmacological stress, is associated with higher frequency of retrospectively reported angina during the day. Psychosocial stressors related to mental stress ischemia may be important contributory factor to daily angina.

Ischemic heart disease in women: a focus on risk factors

Heart disease remains a major contributor to morbidity and mortality in women in the United States and worldwide. This review highlights known and emerging risk factors for ischemic heart disease (IHD) in women. Traditional Framingham risk factors such as hypertension, hyperlipidemia, diabetes, smoking, as well as lifestyle habits such as unhealthy diet and sedentary lifestyle are all modifiable. Health care providers should be aware of emerging cardiac risk factors in women such as adverse pregnancy outcomes, systemic autoimmune disorders, obstructive sleep apnea, and radiation-induced heart disease; psychosocial factors such as mental stress, depression, anxiety, low socioeconomic status, and work and marital stress play an important role in IHD in women. Appropriate recognition and management of an array of risk factors is imperative given the growing burden of IHD and need to deliver cost-effective, quality care for women.

Association between anger and mental stress-induced myocardial ischemia

BACKGROUND

Mental stress-induced myocardial ischemia is associated with adverse prognosis in coronary artery disease patients. Anger is thought to be a trigger of acute coronary syndromes and is associated with increased cardiovascular risk; however, little direct evidence exists for a link between anger and myocardial ischemia.

METHODS

[(99m)Tc]-sestamibi single-photon emission tomography was performed at rest, after mental stress (a social stressor with a speech task) and after exercise/pharmacologic stress. Summed scores of perfusion abnormalities were obtained by observer-independent software. A summed-difference score, the difference between stress and rest scores, was used to quantify myocardial ischemia under both stress conditions. The Spielberger's State-Trait Anger Expression Inventory was used to assess different anger dimensions.

RESULTS

The mean age was 50 years, 50% were female, and 60% were non-white. After adjusting for demographic factors, smoking, coronary artery disease severity, depressive, and anxiety symptoms, each IQR increment in state-anger score was associated with 0.36 U-adjusted increase in ischemia as measured by the summed-difference score (95% CI 0.14-0.59); the corresponding association for trait anger was 0.95 (95% CI 0.21-1.69). Anger expression scales were not associated with ischemia. None of the anger dimensions was related to ischemia during exercise/pharmacologic stress.

CONCLUSION

Anger, both as an emotional state and as a personality trait, is significantly associated with propensity to develop myocardial ischemia during mental stress but not during exercise/pharmacologic stress. Patients with this psychologic profile may be at increased risk for silent ischemia induced by emotional stress, and this may translate into worse prognosis.

Blood gene expression profiles suggest altered immune function associated with symptoms of generalized anxiety disorder

Prospective epidemiological studies found that generalized anxiety disorder (GAD) can impair immune function and increase risk for cardiovascular disease or events. Mechanisms underlying the physiological reverberations of anxiety, however, are still elusive. Hence, we aimed to investigate molecular processes mediating effects of anxiety on physical health using blood gene expression profiles of 336 community participants (157 anxious and 179 control). We examined genome-wide differential gene expression in anxiety, as well as associations between nine major modules of co-regulated transcripts in blood gene expression and anxiety. No significant differential expression was observed in women, but 631 genes were differentially expressed between anxious and control men at the false discovery rate of 0.1 after controlling for age, body mass index, race, and batch effect. Gene set enrichment analysis (GSEA) revealed that genes with altered expression levels in anxious men were involved in response of various immune cells to vaccination and to acute viral and bacterial infection, and in a metabolic network affecting traits of metabolic syndrome. Further, we found one set of 260 co-regulated genes to be significantly associated with anxiety in men after controlling for the relevant covariates, and demonstrate its equivalence to a component of the stress-related conserved transcriptional response to adversity profile. Taken together, our results suggest potential molecular pathways that can explain negative effects of GAD observed in epidemiological studies. Remarkably, even mild anxiety, which most of our participants had, was associated with observable changes in immune-related gene expression levels. Our findings generate hypotheses and provide incremental insights into molecular mechanisms mediating negative physiological effects of GAD.

Depressive symptoms are associated with mental stress-induced myocardial ischemia after acute myocardial infarction

OBJECTIVES

Depression is an adverse prognostic factor after an acute myocardial infarction (MI), and an increased propensity toward emotionally-driven myocardial ischemia may play a role. We aimed to examine the association between depressive symptoms and mental stress-induced myocardial ischemia in young survivors of an MI.

METHODS

We studied 98 patients (49 women and 49 men) age 38-60 years who were hospitalized for acute MI in the previous 6 months. Patients underwent myocardial perfusion imaging at rest, after mental stress (speech task), and after exercise or pharmacological stress. A summed difference score (SDS), obtained with observer-independent software, was used to quantify myocardial ischemia under both stress conditions. The Beck Depression Inventory-II (BDI-II) was used to measure depressive symptoms, which were analyzed as overall score, and as separate somatic and cognitive depressive symptom scores.

RESULTS

There was a significant positive association between depressive symptoms and SDS with mental stress, denoting more ischemia. After adjustment for demographic and lifestyle factors, disease severity and medications, each incremental depressive symptom was associated with 0.14 points higher SDS. When somatic and cognitive depressive symptoms were examined separately, both somatic [β = 0.17, 95% CI: (0.04, 0.30), p = 0.01] and cognitive symptoms [β = 0.31, 95% CI: (0.07, 0.56), p = 0.01] were significantly associated with mental stress-induced ischemia. Depressive symptoms were not associated with ischemia induced by exercise or pharmacological stress.

CONCLUSION

Among young post-MI patients, higher levels of both cognitive and somatic depressive symptoms are associated with a higher propensity to develop myocardial ischemia with mental stress, but not with physical (exercise or pharmacological) stress.

Meta-analysis of mental stress-induced myocardial ischemia and subsequent cardiac events in patients with coronary artery disease

Mental stress-induced myocardial ischemia (MSIMI) has been associated with adverse prognosis in patients with coronary artery disease (CAD), but whether this is a uniform finding across different studies has not been described. We conducted a systematic review and meta-analysis of prospective studies examining the association between MSIMI and adverse outcome events in patients with stable CAD. We searched PubMed, EMBASE, Web of Science, and PsycINFO databases for English language prospective studies of patients with CAD who underwent standardized mental stress testing to determine presence of MSIMI and were followed up for subsequent cardiac events or total mortality. Our outcomes of interest were CAD recurrence, CAD mortality, or total mortality. A summary effect estimate was derived using a fixed-effects meta-analysis model. Only 5 studies, each with a sample size of <200 patients and fewer than 50 outcome events, met the inclusion criteria. The pooled samples comprised 555 patients with CAD (85% male) and 117 events with a range of follow-up from 35 days to 8.8 years. Pooled analysis showed that MSIMI was associated with a twofold increased risk of a combined end point of cardiac events or total mortality (relative risk 2.24, 95% confidence interval 1.59 to 3.15). No heterogeneity was detected among the studies (Q=0.39, I2=0.0%, p=0.98). In conclusion, although few selected studies have examined the association between MSIMI and adverse events in patients with CAD, all existing investigations point to approximately a doubling of risk. Whether this increased risk is generalizable to the CAD population at large and varies in patient subgroups warrant further investigation.

Current perspective on mental stress-induced myocardial ischemia

Mental stress and emotional arousal can act as triggers of myocardial infarction and other adverse cardiovascular outcomes. This editorial presents an overview of the research on mental stress-induced myocardial ischemia (MSIMI) and comments on two investigations examining MSIMI published in this journal. These studies confirm that MSIMI is frequently observed in patients with coronary artery disease and that characteristics, such as being a woman younger than 50 years and depression, may increase the relative risk of MSIMI. The method used for determining MSIMI (i.e., assessing cardiac function as determined by echocardiography versus measurement of myocardial perfusion using single-photon emission computed tomography), as well as the nature of the mental stress protocols (i.e., one stress task versus several repeated tasks), may have important effects on the findings of MSIMI research and on their interpretation. An overview of clinical characteristics of MSIMI is presented, and the article concludes with possible directions for future MSIMI research.