Prognostic implications of mental stress-induced silent left ventricular dysfunction in patients with stable angina pectoris

The prognostic study of mental stress-induced myocardial ischemia in coronary revascularization patients with depression/anxiety: rationale and design

BACKGROUND

Mental stress-induced myocardial ischemia (MSIMI) frequently occurs in patients with coronary artery disease (CAD), and is even more common in patients with co-occurring CAD and depression/anxiety. MSIMI appears to be a poor prognostic factor for CAD, but existing data on depression/anxiety patients are limited.

METHODS

This cohort study will consecutively screen 2,647 CAD patients between 2023 and 2025. Included subjects will need to have received coronary revascularization and also have depression and/or anxiety at baseline. This study will enroll 360 subjects who meet the criteria. Two mental stress tests will be carried out in each patient at 1 month and 1 year timelines after coronary revascularization, using Stroop color word tests. MSIMI will be assessed by ^99 m-Tc-sestamibi myocardial perfusion imaging. The endothelial function will be assessed by EndoPAT. Furthermore, we will dynamically monitor patients' health and mental conditions every 3 months. The mean follow-up time will be 1 year. The primary endpoint is the major adverse cardiac events, a composite of all-cause death, cardiac death, myocardial infarction, stroke, or unplanned revascularization. Secondary endpoints will include overall health and mental conditions. The reproducibility of mental stress combined with myocardial perfusion for detecting MSIMI and comparisons between coronary stenosis and ischemic segments will also be included.

CONCLUSIONS

This cohort study will provide information on MSIMI outcomes in CAD patients who also have comorbid depression/anxiety after revascularization. In addition, understanding the long-term dynamics of MSIMI and the match between coronary stenosis and ischemia will provide insight into MSIMI mechanisms.

TRAIL REGISTRATION

ChiCTR2200055792, 2022.1.20, www.medresman.org.cn.

Mental Stress and Its Effects on Vascular Health

Coronary artery disease continues to be a major cause of morbidity and mortality despite significant advances in risk stratification and management. This has prompted the search for alternative nonconventional risk factors that may provide novel therapeutic targets. Psychosocial stress, or mental stress, has emerged as an important risk factor implicated in a higher incidence of cardiovascular events, and although our understanding of this far ranging and interesting phenomenon has developed greatly over recent times, there is still much to be learned regarding how to measure mental stress and how it may impact physical health. With the current coronavirus disease 2019 global pandemic and its incumbent lockdowns and social distancing, understanding the potentially harmful biological effects of stress related to life-changing events and social isolation has become even more important. In the current review our multidisciplinary team discusses stress from a psychosocial perspective and aims to define psychological stress as rigorously as possible; discuss the pathophysiologic mechanisms by which stress may mediate cardiovascular disease, with a particular focus to its effects on vascular health; outline existing methods and approaches to quantify stress by means of a vascular biomarker; outline the mechanisms whereby psychosocial stressors may have their pathologic effects ultimately transduced to the vasculature through the neuroendocrine immunologic axis; highlight areas for improvement to refine existing approaches in clinical research when studying the consequences of psychological stress on cardiovascular health; and discuss evidence-based therapies directed at reducing the deleterious effects of mental stress including those that target endothelial dysfunction. To this end we searched PubMed and Google Scholar to identify studies evaluating the relationship between mental or psychosocial stress and cardiovascular disease with a particular focus on vascular health. Search terms included "myocardial ischemia," "coronary artery disease," "mental stress," "psychological stress," "mental∗ stress∗," "psychologic∗ stress∗," and "cardiovascular disease∗." The search was limited to studies published in English in peer-reviewed journals between 1990 and the present day. To identify potential studies not captured by our database search strategy, we also searched studies listed in the bibliography of relevant publications and reviews.

Association of Mental Stress-Induced Myocardial Ischemia With Cardiovascular Events in Patients With Coronary Heart Disease

IMPORTANCE

Mental stress-induced myocardial ischemia is a recognized phenomenon in patients with coronary heart disease (CHD), but its clinical significance in the contemporary clinical era has not been investigated.

OBJECTIVE

To compare the association of mental stress-induced or conventional stress-induced ischemia with adverse cardiovascular events in patients with CHD.

DESIGN, SETTING, AND PARTICIPANTS

Pooled analysis of 2 prospective cohort studies of patients with stable CHD from a university-based hospital network in Atlanta, Georgia: the Mental Stress Ischemia Prognosis Study (MIPS) and the Myocardial Infarction and Mental Stress Study 2 (MIMS2). Participants were enrolled between June 2011 and March 2016 (last follow-up, February 2020).

EXPOSURES

Provocation of myocardial ischemia with a standardized mental stress test (public speaking task) and with a conventional (exercise or pharmacological) stress test, using single-photon emission computed tomography.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of cardiovascular death or first or recurrent nonfatal myocardial infarction. The secondary end point additionally included hospitalizations for heart failure.

RESULTS

Of the 918 patients in the total sample pool (mean age, 60 years; 34% women), 618 participated in MIPS and 300 in MIMS2. Of those, 147 patients (16%) had mental stress-induced ischemia, 281 (31%) conventional stress ischemia, and 96 (10%) had both. Over a 5-year median follow-up, the primary end point occurred in 156 participants. The pooled event rate was 6.9 per 100 patient-years among patients with and 2.6 per 100 patient-years among patients without mental stress-induced ischemia. The multivariable adjusted hazard ratio (HR) for patients with vs those without mental stress-induced ischemia was 2.5 (95% CI, 1.8-3.5). Compared with patients with no ischemia (event rate, 2.3 per 100 patient-years), patients with mental stress-induced ischemia alone had a significantly increased risk (event rate, 4.8 per 100 patient-years; HR, 2.0; 95% CI, 1.1-3.7) as did patients with both mental stress ischemia and conventional stress ischemia (event rate, 8.1 per 100 patient-years; HR, 3.8; 95% CI, 2.6-5.6). Patients with conventional stress ischemia alone did not have a significantly increased risk (event rate, 3.1 per 100 patient-years; HR, 1.4; 95% CI, 0.9-2.1). Patients with both mental stress ischemia and conventional stress ischemia had an elevated risk compared with patients with conventional stress ischemia alone (HR, 2.7; 95% CI, 1.7-4.3). The secondary end point occurred in 319 participants. The event rate was 12.6 per 100 patient-years for patients with and 5.6 per 100 patient-years for patients without mental stress-induced ischemia (adjusted HR, 2.0; 95% CI, 1.5-2.5).

CONCLUSIONS AND RELEVANCE

Among patients with stable coronary heart disease, the presence of mental stress-induced ischemia, compared with no mental stress-induced ischemia, was significantly associated with an increased risk of cardiovascular death or nonfatal myocardial infarction. Although these findings may provide insights into mechanisms of myocardial ischemia, further research is needed to assess whether testing for mental stress-induced ischemia has clinical value.

The Foundational Role of Cardiovascular Imaging in the Characterization of Mental Stress-Induced Myocardial Ischemia in Patients with Coronary Artery Disease

PURPOSE OF REVIEW

Mental stress-provoked myocardial ischemia (MSIMI) is an ischemic phenomenon provoked by the experience of psychologically stressful circumstances. While MSIMI was initially identified 50 years ago during activities of daily living through the use of wearable Holter monitor, subsequent research utilized the technologies of cardiac imaging-ventriculography and myocardial perfusion-under controlled conditions to pursue an understanding of pathophysiology and prognosis. This work revealed that MSIMI occurs in almost half of patients with stable coronary artery disease (CAD) and is associated with cardiac events and early mortality. We provide a focused review of the instrumental role that cardiac imaging has played in elucidating how stress affects cardiac physiology and how emerging diagnostic techniques will allow for further research on stress-mediated changes in the coronary macro- and microvasculature.

RECENT FINDINGS

Observations about the cardiac response to mental stress diverge from underlying cornerstones of the traditional CAD paradigm which is based upon myocardial oxygen demand and the degree of epicardial coronary stenosis. Evidence from studies utilizing non-invasive and invasive studies of coronary perfusion indicates perturbations in the microvascular compartment in response to mental stress. Cardiovascular imaging enjoined with mental stress provocation may be a commanding tool to advance our understanding of non-obstructive CAD and the coronary microvasculature. This further understanding will facilitate incorporation of mental stress testing in the clinical care of patients with discrepant diagnostic work-up of CAD and in patients who experience anginal symptoms due to non-exertional and/or emotional triggers. Such algorithms will be crucial to identify treatment targets to modify the risk associated with mental stress-associated ischemia and adverse prognosis.

Cardiovascular Imaging of Biology and Emotion: Considerations Toward a New Paradigm

Central activation in response to emotion and cognitive stress induces perturbations in the heart and the peripheral vasculature that differ in physiology and clinical manifestations when compared with exercise-induced changes. While our conventional framework of epicardial coronary artery disease is foundational in cardiology, an expanded paradigm is required to address the cardiovascular response to mental stress (MS) and its associated risks, thus addressing the intersection of the patient's ecological and psychosocial experience with cardiovascular biology. To advance the field of MS in cardiovascular health, certain core challenges must be addressed. These include differences in the trigger activation between exercise and emotion, identification and interpretation of imaging cues as measures of pathophysiologic changes, characterization of the vascular response, and identification of central and peripheral treatment targets. Sex and psychosocial determinants of health are important in understanding the emerging overlap of MS-induced myocardial ischemia with microvascular dysfunction and symptoms in the absence of obstructive disease. In overcoming these critical knowledge gaps, integration of the field of MS will require implementation studies to guide use of MS testing, to support diagnosis of MS induced cardiac and vascular pathophysiology, to assess prognosis, and understand the role of endotying to direct therapy.

Brain Correlates of Mental Stress-Induced Myocardial Ischemia

OBJECTIVE

Coronary artery disease (CAD) is a major cause of morbidity and mortality, and despite important advances in our understanding of this disorder, the underlying mechanisms remain under investigation. Recently, increased attention has been placed on the role of behavioral factors such as emotional stress on CAD risk. Brain areas involved in memory and the stress response, including medial prefrontal cortex, insula, and parietal cortex, also have outputs to the peripheral cardiovascular system. The purpose of this study was to assess the effects of mental stress on brain and cardiac function in patients with CAD.

METHODS

CAD patients (N = 170) underwent cardiac imaging with [Tc-99m] sestamibi single-photon emission tomography at rest and during a public speaking mental stress task. On another day, they underwent imaging of the brain with [O-15] water positron emission tomography (PET) during mental stress (arithmetic and public speaking) and control conditions.

RESULTS

Patients with mental stress-induced myocardial ischemia showed increased activation with stress in anterior cingulate, inferior frontal gyrus, and parietal cortex (p < .005). This was seen with both arithmetic stress and public speaking stress. Arithmetic stress was additionally associated with left insula activation, and public speaking with right pre/postcentral gyrus and middle temporal gyrus activation (p < .005).

CONCLUSIONS

These findings suggest that mental stress-induced myocardial ischemia is associated with activation in brain areas involved in the stress response and autonomic regulation of the cardiovascular system. Altered brain reactivity to stress could possibly represent a mechanism through which stress leads to increased risk of CAD-related morbidity and mortality.

Comparison of autonomic stress reactivity in young healthy versus aging subjects with heart disease

BACKGROUND

The autonomic response to acute emotional stress can be highly variable, and pathological responses are associated with increased risk of adverse cardiovascular events. We evaluated the autonomic response to stress reactivity of young healthy subjects and aging subjects with coronary artery disease to understand how the autonomic stress response differs with aging.

METHODS

Physiologic reactivity to arithmetic stress in a cohort of 25 young, healthy subjects (< 30 years) and another cohort of 25 older subjects (> 55 years) with CAD was evaluated using electrocardiography, impedance cardiography, and arterial pressure recordings. Stress-related changes in the pre-ejection period (PEP), which measures sympathetic activity, and high frequency heart rate variability (HF HRV), which measures parasympathetic activity, were analyzed as primary outcomes.

RESULTS

Mental stress reduced PEP in both groups (p<0.01), although the decrease was 50% greater in the healthy group. Mean HF HRV decreased significantly in the aging group only (p = 0.01).

DISCUSSION

PEP decreases with stress regardless of health and age status, implying increased sympathetic function. Its decline with stress may be attenuated in CAD. The HF HRV (parasympathetic) stress reactivity is more variable and attenuated in younger individuals; perhaps this is related to a protective parasympathetic reflex.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02657382.

Hemodynamic, catecholamine, vasomotor and vascular responses: Determinants of myocardial ischemia during mental stress

AIMS

Mental stress-induced myocardial ischemia (MSIMI) in patients with coronary artery disease (CAD) is associated with adverse cardiovascular outcomes. We aim to assess hemodynamic, neuro-hormonal, endothelial, vasomotor and vascular predictors of MSIMI.

METHODS AND RESULTS

We subjected 660 patients with stable CAD to 99mTc sestamibi myocardial perfusion imaging at rest, with mental (speech task) and with conventional (exercise/pharmacological) stress. Endothelium-dependent flow-mediated dilation (FMD), microvascular reactivity [reactive hyperemia index (RHI)] and arterial stiffness [pulse wave velocity (PWV)] were measured at rest and 30-min after mental stress. The digital microvascular vasomotor response during mental stress was assessed using peripheral arterial tonometry (PAT). A total of 106(16.1%) patients had MSIMI. Mental stress was accompanied by significant increases in rate-pressure-product (heart rate x systolic blood pressure; RPP), epinephrine levels and PWV, and significant decreases in FMD and PAT ratio denoting microvascular constriction. In comparison to those with no MSIMI, patients with MSIMI had higher hemodynamic and digital vasoconstrictive responses (p<0.05 for both), but did not differ in epinephrine, endothelial or macrovascular responses. Only presence of ischemia during conventional stress (OR of 7.1, 95%CI of 4.2, 11.9), high hemodynamic response (OR for RPP response≥vs<ROC cutoff of 1.8, 95%CI of 1.1, 2.8), and high digital vasoconstriction (OR for PAT ratio<vs≥ROC cutoff of 2.1, 95%CI of 1.3, 3.3) were independent predictors of MSIMI.

CONCLUSION

Ischemia during conventional stress testing and hemodynamic and vasoconstrictive responses to mental stress can help predict subjects with CAD at greater risk of developing MSIMI.

Positive and Negative Affect Is Related to Experiencing Chest Pain During Exercise-Induced Myocardial Ischemia

OBJECTIVE

Silent myocardial ischemia is thought to be associated with worse cardiovascular outcomes due to a lack of perception of pain cues that initiate treatment seeking. Negative affect (NA) has been associated with increased pain reporting and positive affect (PA) with decreased pain reporting, but these psychological factors have not been examined within the context of myocardial ischemia. This study evaluated the associations between PA, NA, and chest pain reporting in patients with and without ischemia during exercise testing.

METHODS

A total of 246 patients referred for myocardial perfusion single-photon emission computed tomography exercise stress testing completed the positive and negative affect schedule-expanded version, a measure of PA and NA. Presence of chest pain and myocardial ischemia were evaluated using standardized protocols.

RESULTS

Logistic regression analyses revealed that for every 1-point increase in NA, there was a 13% higher chance for ischemic patients (odds ratio [OR] = 1.13; 95% confidence interval [CI] = 1.02 to 1.26) and an 11% higher chance in nonischemic patients (OR = 1.11; 95% CI = 1.03 to 1.19) to report chest pain. A significant interaction of PA and NA on chest pain reporting (β = 0.02; 95% CI = 0.002 to 0.031) was also observed; nonischemic patients with high NA and PA reported more chest pain (57%) versus patients with low NA and low PA (13%), with high NA and low PA (17%), and with high PA and low NA (7%).

CONCLUSIONS

Patients who experience higher NA are more likely to report experiencing chest pain. In patients without ischemia, high NA and PA was also associated with a higher likelihood of reporting chest pain. Results suggest that high levels of PA as well as NA may increase the experience and/or reporting of chest pain.

The Mental Stress Ischemia Prognosis Study: Objectives, Study Design, and Prevalence of Inducible Ischemia

OBJECTIVE

Mental stress-induced myocardial ischemia (MSIMI) is a common phenomenon in patients with coronary artery disease (CAD), but contemporary studies of its prognostic significance and its underlying pathophysiology are limited.

METHODS

We prospectively enrolled patients with confirmed CAD in the Mental Stress Ischemia Prognosis Study (MIPS) between 2011 and 2014. All patients underwent mental stress testing using a standardized public speaking task, and ischemia was detected by Tc-sestamibi myocardial perfusion imaging. Patients also underwent conventional stress testing for myocardial ischemia (CSIMI) using exercise or pharmacological stress testing. Furthermore, digital microvascular flow, endothelial function, arterial stiffness, and blood sample collections were performed before, during, and after mental stress. Two-year adverse clinical outcomes are being assessed.

RESULTS

Six-hundred ninety-five patients completed baseline enrollment in the MIPS. Their mean (standard deviation) age was 62.9 (9.1) years, 72% were men, 30% were African American, and 32% had a history myocardial infarction. The prevalence of MSIMI and CSIMI is 16.1% and 34.7%, respectively. A total of 151 patients (22.9%) had only CSIMI, 28 (4.2%) had only MSIMI, and 78 (11.8%) had both MSIMI and CSIMI. Patients with ischemia had a lower ejection fraction and higher prevalence of previous coronary artery bypass grafting compared with those without inducible ischemia (p < .050). The prevalence of obstructive CAD was not statistically different between patients with and without MSIMI (p = .426); in contrast, it was higher in patients with CSIMI (p < .001).

CONCLUSIONS

The MIPS data will provide useful information to assess the prognostic significance and underlying mechanisms of MSIMI.

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.

Body Mass Index and Risk for Mental Stress Induced Ischemia in Coronary Artery Disease

Acute emotionally reactive mental stress (MS) can provoke prognostically relevant deficits in cardiac function and myocardial perfusion, and chronic inflammation increases risk for this ischemic phenomenon. We have described parasympathetic withdrawal and generation of inflammatory factors in MS. Adiposity is also associated with elevated markers of chronic inflammation. High body mass index (BMI) is frequently used as a surrogate for assessment of excess adiposity, and associated with traditional CAD risk factors, and CAD mortality. BMI is also associated with autonomic dysregulation, adipose tissue derived proinflammatory cytokines, which are also attendant to emotion provoked myocardial ischemia. Thus, we sought to determine if body mass index (BMI) contributes to risk of developing myocardial ischemia provoked by mental stress. We performed a prospective interventional study in a cohort of 161 patients with stable CAD. They completed an assessment of myocardial blood flow with single photon emission computed tomography (SPECT) simultaneously during 2 conditions: laboratory mental stress and at rest. Multivariate logistic regression determined the independent contribution of BMI to the occurrence of mental-stress induced ischemia. Mean age was 65.6 ±9.0 years; 87.0% had a history of hypertension, and 28.6% had diabetes. Mean BMI was 30.4 ± 4.7. Prevalence of mental stress ischemia was 39.8%. BMI was an independent predictor of mental stress ischemia, OR=1.10, 95% CI [1.01-1.18] for one-point increase in BMI and OR=1.53, 95% CI [1.06-2.21] for a 4.7 point increase in BMI (one standard deviation beyond the cohort BMI mean), p=0.025 for all. These data suggest that BMI may serve as an independent risk marker for mental stress ischemia. The factors attendant with greater BMI, which include autonomic dysregulation and inflammation, may represent pathways by which high BMI contribute to this risk and serve as a conceptual construct to replicate these findings in larger CAD populations.

High Concordance Between Mental Stress-Induced and Adenosine-Induced Myocardial Ischemia Assessed Using SPECT in Heart Failure Patients: Hemodynamic and Biomarker Correlates

Mental stress can trigger myocardial ischemia, but the prevalence of mental stress-induced ischemia in congestive heart failure (CHF) patients is unknown. We characterized mental stress-induced and adenosine-induced changes in myocardial perfusion and neurohormonal activation in CHF patients with reduced left-ventricular function using SPECT to precisely quantify segment-level myocardial perfusion.

METHODS

Thirty-four coronary artery disease patients (mean age±SD, 62±10 y) with CHF longer than 3 mo and ejection fraction less than 40% underwent both adenosine and mental stress myocardial perfusion SPECT on consecutive days. Mental stress consisted of anger recall (anger-provoking speech) followed by subtraction of serial sevens. The presence and extent of myocardial ischemia was quantified using the conventional 17-segment model.

RESULTS

Sixty-eight percent of patients had 1 ischemic segment or more during mental stress and 81% during adenosine. On segment-by-segment analysis, perfusion with mental stress and adenosine were highly correlated. No significant differences were found between any 2 time points for B-type natriuretic peptide, tumor necrosis factor-α, IL-1b, troponin, vascular endothelin growth factor, IL-17a, matrix metallopeptidase-9, or C-reactive protein. However, endothelin-1 and IL-6 increased, and IL-10 decreased, between the stressor and 30 min after stress. Left-ventricular end diastolic dimension was 179±65 mL at rest and increased to 217±71 after mental stress and 229±86 after adenosine (P<0.01 for both). Resting end systolic volume was 129±60 mL at rest and increased to 158±66 after mental stress (P<0.05) and 171±87 after adenosine (P<0.07), with no significant differences between adenosine and mental stress. Ejection fraction was 30±12 at baseline, 29±11 with mental stress, and 28±10 with adenosine (P=not significant).

CONCLUSION

There was high concordance between ischemic perfusion defects induced by adenosine and mental stress, suggesting that mental stress is equivalent to pharmacologic stress in eliciting clinically significant myocardial perfusion defects in CHF patients. Cardiac dilatation suggests clinically important changes with both conditions. Psychosocial stressors during daily life may contribute to the ischemic burden of CHF patients with coronary artery disease.

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.

Myocardial ischemia and angiotensin-converting enzyme inhibition: comparison of ischemia during mental and physical stress

OBJECTIVE

Mental stress provokes myocardial ischemia in many patients with stable coronary artery disease (CAD). Mental stress-induced myocardial ischemia (MSIMI) portends a worse prognosis, independent of standard cardiac risk factors or outcome of traditional physical stress testing. Angiotensin II plays a significant role in the physiological response to stress, but its role in MSIMI remains unknown. Our aim was to evaluate whether the use of angiotensin-converting enzyme inhibitors (ACEIs) is associated with a differential effect on the incidence of MSIMI compared with ischemia during physical stress.

METHODS

Retrospective analysis of 218 patients with stable CAD, including 110 on ACEI, was performed. 99m-Tc-sestamibi myocardial perfusion imaging was used to define ischemia during mental stress, induced by a standardized public speaking task, and during physical stress, induced by either exercise or adenosine.

RESULTS

Overall, 40 patients (18%) developed MSIMI and 80 patients (37%) developed ischemia during physical stress. MSIMI occurred less frequently in patients receiving ACEIs (13%) compared with those not on ACEIs (24%; p = .030, adjusted odds ratio = 0.42, 95% confidence interval = 0.19-0.91). In contrast, the frequency of myocardial ischemia during physical stress testing was similar in both groups (39% versus 35% in those on and not on ACEIs, respectively); adjusted odds ratio = 0.91, 95% confidence interval = 0.48-1.73).

CONCLUSION

In this retrospective study, patients using ACEI therapy displayed less than half the risk of developing ischemia during mental stress but not physical stress. This possible beneficial effect of ACEIs on MSIMI may be contributing to their salutary effects in CAD.

Myocardial ischemia during mental stress: role of coronary artery disease burden and vasomotion

Background

Mental stress–induced myocardial ischemia (MSIMI) is associated with adverse prognosis in patients with coronary artery disease (CAD), yet the mechanisms underlying this phenomenon remain unclear. We hypothesized that compared with exercise/pharmacological stress–induced myocardial ischemia (PSIMI) that is secondary to the atherosclerotic burden of CAD, MSIMI is primarily due to vasomotor changes.

Methods and Results

Patients with angiographically documented CAD underwent ^99mTc‐sestamibi myocardial perfusion imaging at rest and following both mental and physical stress testing, performed on separate days. The severity and extent of CAD were quantified using the Gensini and Sullivan scores. Peripheral arterial tonometry (Itamar Inc) was used to assess the digital microvascular tone during mental stress as a ratio of pulse wave amplitude during speech compared with baseline. Measurements were made in a discovery sample (n=225) and verified in a replication sample (n=159). In the pooled (n=384) sample, CAD severity and extent scores were not significantly different between those with and without MSIMI, whereas they were greater in those with compared with those without PSIMI (P<0.04 for all). The peripheral arterial tonometry ratio was lower in those with compared with those without MSIMI (0.55±0.36 versus 0.76±0.52, P=0.009). In a multivariable analysis, the peripheral arterial tonometry ratio was the only independent predictor of MSIMI (P=0.009), whereas angiographic severity and extent of CAD independently predicted PSIMI.

Conclusions

The degree of digital microvascular constriction, and not the angiographic burden of CAD, is associated with MSIMI. Varying causes of MSIMI compared with PSIMI may require different therapeutic interventions that require further study.

Effect of escitalopram on mental stress-induced myocardial ischemia: results of the REMIT trial

IMPORTANCE

Mental stress can induce myocardial ischemia and also has been implicated in triggering cardiac events. However, pharmacological interventions aimed at reducing mental stress-induced myocardial ischemia (MSIMI) have not been well studied.

OBJECTIVE

To examine the effects of 6 weeks of escitalopram treatment vs placebo on MSIMI and other psychological stress-related biophysiological and emotional parameters.

DESIGN, SETTING, AND PARTICIPANTS

The REMIT (Responses of Mental Stress Induced Myocardial Ischemia to Escitalopram Treatment) study, a randomized, double-blind, placebo-controlled trial of patients with clinically stable coronary heart disease and laboratory-diagnosed MSIMI. Enrollment occurred from July 24, 2007, through August 24, 2011, at a tertiary medical center.

INTERVENTIONS

Eligible participants were randomized 1:1 to receive escitalopram (dose began at 5 mg/d, with titration to 20 mg/d in 3 weeks) or placebo over 6 weeks.

MAIN OUTCOMES AND MEASURES

Occurrence of MSIMI, defined as development or worsening of regional wall motion abnormality; left ventricular ejection fraction reduction of 8% or more; and/or horizontal or down-sloping ST-segment depression of 1 mm or more in 2 or more leads, lasting for 3 or more consecutive beats, during 1 or more of 3 mental stressor tasks.

RESULTS

Of 127 participants randomized to receive escitalopram (n = 64) or placebo (n = 63), 112 (88.2%) completed end point assessments (n = 56 in each group). At the end of 6 weeks, more patients taking escitalopram (34.2% [95% CI, 25.4%-43.0%]) had absence of MSIMI during the 3 mental stressor tasks compared with patients taking placebo (17.5% [95% CI, 10.4%-24.5%]), based on the unadjusted multiple imputation model for intention-to-treat analysis. A significant difference favoring escitalopram was observed (odds ratio, 2.62 [95% CI, 1.06-6.44]). Rates of exercise-induced ischemia were slightly lower at 6 weeks in the escitalopram group (45.8% [95% CI, 36.6%-55.0%]) than in patients receiving placebo (52.5% [95% CI, 43.3%-61.8%]), but this difference was not statistically significant (adjusted odds ratio; 1.24 [95% CI, 0.60-2.58]; P = .56).

CONCLUSIONS AND RELEVANCE

Among patients with stable coronary heart disease and baseline MSIMI, 6 weeks of escitalopram, compared with placebo, resulted in a lower rate of MSIMI. There was no statistically significant difference in exercise-induced ischemia. Replication of these results in multicenter settings and investigations of other medications for reducing MSIMI are needed.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00574847.

Prevalence and clinical characteristics of mental stress-induced myocardial ischemia in patients with coronary heart disease

OBJECTIVES

The goal of this study was to evaluate the prevalence and clinical characteristics of mental stress-induced myocardial ischemia.

BACKGROUND

Mental stress-induced myocardial ischemia is prevalent and a risk factor for poor prognosis in patients with coronary heart disease, but past studies mainly studied patients with exercise-induced myocardial ischemia.

METHODS

Eligible patients with clinically stable coronary heart disease, regardless of exercise stress testing status, underwent a battery of 3 mental stress tests followed by a treadmill test. Stress-induced ischemia, assessed by echocardiography and electrocardiography, was defined as: 1) development or worsening of regional wall motion abnormality; 2) left ventricular ejection fraction reduction ≥ 8%; and/or 3) horizontal or downsloping ST-segment depression ≥ 1 mm in 2 or more leads lasting for ≥ 3 consecutive beats during at least 1 mental test or during the exercise test.

RESULTS

Mental stress-induced ischemia occurred in 43.45%, whereas exercise-induced ischemia occurred in 33.79% (p = 0.002) of the study population (N = 310). Women (odds ratio [OR]: 1.88), patients who were not married (OR: 1.99), and patients who lived alone (OR: 2.24) were more likely to have mental stress-induced ischemia (all p < 0.05). Multivariate analysis showed that compared with married men or men living with someone, unmarried men (OR: 2.57) and married women (OR: 3.18), or living alone (male OR: 2.25 and female OR: 2.72, respectively) had higher risk for mental stress-induced ischemia (all p < 0.05).

CONCLUSIONS

Mental stress-induced ischemia is more common than exercise-induced ischemia in patients with clinically stable coronary heart disease. Women, unmarried men, and individuals living alone are at higher risk for mental stress-induced ischemia. (Responses of Myocardial Ischemia to Escitalopram Treatment [REMIT]; NCT00574847).

The 'perfect storm' and acute coronary syndrome onset: do psychosocial factors play a role?

The revolution in cardiac care over the past two decades, characterized by emergent revascularization, drug eluting stents, anti-platelet medications, and advanced imaging has had little impact on overall ACS recurrence, or ACS prevention. The "Perfect Storm" refers to a confluence of events and processes, including atherosclerotic plaque, coronary flow dynamics, hemostatic and fibrinolytic function, metabolic and inflammatory conditions, neurohormonal dysregulation, and environmental events that give rise to, and result in an ACS event. In this article we illustrate the limits of the traditional main effect research model, giving a brief description of the current state of knowledge regarding the development of atherosclerotic plaque and the rupturing of these plaques that defines an ACS event. We then apply the Perfect Storm conceptualization to describe a program of research concerning a psychosocial vulnerability factor that contributes to increased risk of recurrent ACS and early mortality, and that has defied our efforts to identify underlying pathophysiology and successfully mount efforts to fully mitigate this risk.

Psychological Correlates of Mental Stress-induced Ischemia in the Laboratory: The Psychophysiological Investigation of Myocardial Ischemia (PIMI) Study

Participants consisted of 184 patients (160 males, 24 females) with positive angiograms or prior myocardial infarctions who displayed at least 1 mm of ST segment depression on a standardized treadmill test. Mean scores on the Reward Dependence subscale of the Tridimensional Personality Questionnaire were higher in patients displaying ischemia during mental stress. Patients who reported higher levels of irritability/anger in response to the Speech stressor were also more likely to display ischemia. However, this result was primarily a result of the females in the sample whose ratings of interest and irritability were associated with ischemia during the Speech task. Psychometric measures previously found in prospective studies to predict acute cardiac events were unrelated to mental stress-induced ischemia in the laboratory.

Mental stress and ischemic heart disease: evolving awareness of a complex association

The connection between cardiovascular disease and psychosocial risk factors has been the subject of an ever-growing body of literature over the last 50 years. Studies on the role of negative emotions, personality traits, chronic stress and social determinants have brought to light their possible role in triggering acute coronary syndromes, although further studies are required to clarify controversial results regarding the association between cardiovascular risk and important psychological problems such as depression and anxiety. The recognition of the role of emotional events in acute coronary syndromes paved the way for provocation experiments, aimed at inducing mental stress in a controlled setting and then documenting reversible impairment of myocardial perfusion, depolarization anomalies and arrhythmias. This ultimately led to the formalization of the concept of mental stress-induced myocardial ischemia. Accumulating evidence on the mechanistic bases of such phenomena outline a wide range of central and peripheral physiological changes associated with emotions and behaviors, whose effects are exerted on the cardiovascular system, sympathetic nervous system and the hypothalamus-hypophysis neuroendocrine axis. This article outlines the main steps in the identification of psychological aspects as cardiovascular risk factors and emphasizes the relevance of emotional stress as a trigger of acute cardiovascular events. Finally, a description is provided of the pathophysiological mechanisms behind mental stress-induced myocardial ischemia and pathways connecting the heart and brain.

Enhancing standard cardiac rehabilitation with stress management training: background, methods, and design for the enhanced study

PURPOSE

Enhancing Standard Cardiac Rehabilitation with Stress Management Training in Patients with Heart Disease (ENHANCED) is a randomized clinical trial funded by the National Heart Lung and Blood Institute to evaluate the effects of stress management training (SMT) on changes in biomarkers of risk and quality of life for patients enrolled in traditional exercise-based cardiac rehabilitation (CR).

METHODS

One hundred fifty cardiac patients recruited from Duke University and the University of North Carolina will be evaluated and randomized to CR enhanced by SMT (including sessions devoted to relaxation training, cognitive restructuring, communication skills, and problem solving) or to standard exercise-based CR. Before and after 12 weeks of treatment, patients will undergo a battery of psychometric questionnaires and evaluation of cardiovascular biomarkers, including measures of flow-mediated dilation, heart rate variability, baroreflex sensitivity, platelet function and inflammation, and ischemia during laboratory mental stress testing. The primary outcomes include a composite measure of stress (distress, depression, anxiety, and hostility and 24-hour urinary catecholamines and cortisol) and a composite measure of cardiac biomarkers of risk (vascular endothelial function, cardiac vagal control, inflammation, platelet function, and mental stress-induced myocardial ischemia). Secondary outcomes include measures of quality of life as well as clinical events, including death, hospitalizations, myocardial infarction, and revascularization procedures.

RESULTS

This article reviews prior studies in the area and describes the design of the ENHANCED study. Several key methodological issues are discussed including the assessment of biomarkers of risk and barriers to the integration of SMT into traditional CR.

CONCLUSIONS

The ENHANCED study will provide important information by determining to what extent SMT combined with exercise-based CR may improve prognosis and quality of life in vulnerable cardiac patients.

Heart-brain interactions in mental stress-induced myocardial ischemia

Myocardial ischemia that results from emotional provocation occurs in as many as 30% to 50% of patients with coronary artery disease during the discourse of their lives. This emotionally provoked or mental stress ischemia is associated with poor prognosis, with emerging treatment strategies. This article outlines the conceptual constructs that support the pathophysiologic underpinnings, and biobehavioral aspects associated with this mental stress ischemia. We review a biobehavioral model in which cognitive stress is transduced in the brain. The response of the brain to psychosocial stress is a highly sophisticated and integrated process by which sensory inputs are evaluated and appraised for their importance in relation to previous experience and current goals. The biologic consequences of such stress transduced in the central nervous system has its effect on cardiovascular flow and function through changes in autonomic balance, which result in various biologic processes that culminate in the perturbation of flow and function of the heart.

Prognosis after change in left ventricular ejection fraction during mental stress testing in patients with stable coronary artery disease

Previous studies of patients with stable coronary artery disease have demonstrated that decreases in the left ventricular ejection fraction (LVEF) during acute mental stress are predictive of adverse clinical outcomes. The aim of the present study was to examine the prospective relation of mental stress on clinical outcomes in a sample of 138 patients with stable coronary artery disease. Patients underwent mental stress testing and were followed for a median of 5.9 years to assess the occurrence of the combined end point of myocardial infarction or all-cause mortality. There were 32 events (17 nonfatal myocardial infarctions and 15 deaths) over the follow-up period. Of the 26 patients who exhibited myocardial ischemia during mental stress testing, 11 (42%) sustained subsequent clinical events, compared to 21 of the 112 patients (19%) who showed no mental stress-induced ischemia. LVEF change during mental stress was also related to the clinical events in a graded, continuous fashion, with each 4% decrease from the LVEF at rest associated with an adjusted hazard ratio of 1.7, (95% confidence interval 1.1 to 2.6, p = 0.011). In conclusion, reductions in the LVEF during mental stress are prospectively associated with adverse clinical outcomes.

Usefulness of peripheral arterial tonometry in the detection of mental stress-induced myocardial ischemia

BACKGROUND

Mental stress-induced myocardial ischemia (MSIMI) identifies a subset of coronary arterial disease (CAD) patients at increased risk for adverse cardiovascular events. Peripheral arterial vasoconstriction has been consistently reported as an underlying mechanism for ischemia development in this setting and as such affords a unique opportunity for the noninvasive detection of this phenomenon.

HYPOTHESIS

We studied the usefulness of a peripheral arterial tonometry (PAT) technique in the detection of MSIMI. We sought to identify response patterns that would predict the development of MSIMI.

METHODS

Participants were 211 patients with documented CAD. Mental stress testing was performed using a public speaking task. Rest-stress myocardial perfusion imaging was the gold standard for ischemia detection. PAT responses were assessed during the 2 phases of the stressful task (stress anticipation and the task performance) and were calculated as a ratio of stress to the resting pulse wave amplitude.

RESULTS

Vascular response during the stress anticipation period (speech preparation) was more pronounced than during the actual speaking task (the mean preparation index was 0.64 +/- 0.53; the mean speech index was 0.72 +/- 0.60; P < 0.001). PAT response during speech preparation had modest accuracy for predicting MSIMI (area under the curve [AUC] was 0.63; 95% confidence interval [CI]: 0.53-0.74, P = 0.015). A PAT index < or = 0.52 was identified as the best cut off value for detecting MSIMI with a sensitivity of 76% and a specificity of 56%.

CONCLUSION

We identified a pattern of peripheral arterial response to mental stress that has a relatively modest accuracy in predicting MSIMI. Further research is needed to validate the findings of this study.

The effect of acute psychological stress on QT dispersion in patients with coronary artery disease

BACKGROUND

An acute psychological stress can precipitate ventricular arrhythmias and sudden cardiac death in patients with coronary artery disease (CAD). However, the physiologic mechanisms by which these effects occur are not entirely clear. Mental stress-induced myocardial ischemia occurs in a significant percentage of the CAD population. It is unknown if the proarrhythmic effects of psychological stress are mediated through the development of myocardial ischemia.

OBJECTIVES

To examine the effects of psychological stress on QT dispersion (QTd) among CAD patients and whether these effects are mediated via the development of myocardial ischemia.

METHODS

Psychological stress was induced using a public speaking task. Twelve-lead electrocardiograms (ECG) were recorded at rest, during mental stress, and during recovery. QTd was calculated as the difference between the longest and the shortest QT interval in the 12-lead ECG. Rest-stress myocardial perfusion imaging was also performed to detect mental stress-induced myocardial ischemia.

RESULTS

Mental stress induced a significant increase in QTd compared to the resting condition (P < 0.001). This effect persisted beyond the first 10 minutes of recovery (P < 0.001). QTd was significantly associated with the development of mental stress ischemia with ischemic patients having significantly higher QTd during mental stress than nonischemic patients (P = 0.006). This finding remained significant after controlling for possible confounding factors (P = 0.01).

CONCLUSION

An acute psychological stress induces a significant increase in QTd, which persists for more than 10 minutes after the cessation of the stressor. This effect seems to be, at least partially, mediated by the development of mental stress-induced myocardial ischemia.

Noninvasive detection of risk for emotion-provoked myocardial ischemia

OBJECTIVES

To test an easily administered, noninvasive technology to identify vulnerability to mental stress ischemia.

BACKGROUND

Myocardial ischemia provoked by emotional stress (MSI) in patients with stable coronary artery disease (CAD) predicts major adverse cardiac events. A clinically useful tool to risk stratify patients on this factor is not available.

METHODS

Patients with documented CAD (n = 68) underwent single photon emission CT myocardial perfusion imaging concurrent with pulse wave amplitude assessment by peripheral arterial tonometry (PAT) during a mental stress protocol of sequential rest and anger stress periods. Heart rate and blood pressure were assessed, and blood was drawn for catecholamine assay, during rest and stress. MSI was defined by the presence of a new perfusion defect during anger stress (n = 26) and the ratio of stress to rest PAT response was calculated.

RESULTS

Patients with MSI had a significantly lower PAT ratio than those without MSI (0.76 +/- 0.04 versus 0.91 +/- 0.05, p = .03). An ROC curve for optimum sensitivity/specificity of PAT ratio as an index of MSI produced a sensitivity of 0.62 and a specificity of 0.63. Among patients taking angiotensin converting enzyme (ACE) inhibitors, the sensitivity and specificity of the test increased to 0.86 and 0.73, respectively; 90% of patients without MSI were correctly identified.

CONCLUSIONS

PAT in concert with ACE inhibition may provide a useful approach to assess risk for MSI. Future studies should help determine how best to utilize this approach for risk assessment in the clinical setting.

Comparison of peripheral arterial response to mental stress in men versus women with coronary artery disease

There are profound gender-related differences in the incidence, presentation, and outcomes of coronary artery disease (CAD). These differences are not entirely explained by traditional cardiovascular risk factors. Nontraditional risk factors, such as psychological traits, have increasingly been recognized as important contributors to the genesis and outcomes of CAD. Mental stress induces significant peripheral arterial vasoconstriction, with consequent increases in heart rate and blood pressure. These changes are thought to underlie the development of myocardial ischemia and other mental stress-induced adverse cardiac events in patients with CAD. This study examined for gender-related differences in peripheral arterial response to mental stress in a cohort of patients with CAD using a novel peripheral arterial tonometric (PAT) technique. There were 211 patients (77 women; 37%) with a documented history of CAD and a mean age of 64 +/- 9 years. Patients were enrolled from August 18, 2004, to February 21, 2007. Mental stress was induced using a public speaking task. Hemodynamic and PAT measurements were recorded during rest and mental stress. The PAT response was calculated as a ratio of pulse wave amplitude during stress to at rest. PAT responses were compared between men and women. The PAT ratio (during stress to at rest) was significantly higher in women compared with men. Mean PAT ratio was 0.80 +/- 0.72 in women compared with 0.59 +/- 0.48 in men (p = 0.032). This finding remained significant after controlling for possible confounding factors (p = 0.037). In conclusion, peripheral vasoconstrictive response to mental stress was more pronounced in men compared with women. This finding may suggest that men have higher susceptibility to mental stress-related adverse effects. Additional studies are needed to determine the significance of this finding.

Variability of myocardial ischemic responses to mental versus exercise or adenosine stress in patients with coronary artery disease

BACKGROUND

Mental stress precipitates myocardial ischemia in a significant percentage of coronary artery disease (CAD) patients. Exercise or adenosine stresses produce different physiologic responses and cause myocardial ischemia via different mechanisms. Little is known about the comparative severity and location of myocardial ischemia provoked by these different stressors. In this study we sought to compare the within-individual ischemic responses to mental versus exercise or adenosine stress in a cohort of CAD patients.

METHODS AND RESULTS

All patients underwent mental stress and either exercise or adenosine testing within a 1-week period. Mental stress was induced via a public speaking task. Rest-stress myocardial perfusion imaging was used with all testing protocols. Participants were 187 patients (65 women [35%]) with a documented history of CAD and a mean age of 64 +/- 9 years. Mental stress-induced myocardial ischemia (MSIMI) was less prevalent and frequently of less magnitude than exercise- or adenosine-induced ischemia. Ischemia induced by exercise or adenosine testing did not accurately predict the development or the location of MSIMI. The overall concordance between these stressors for provoking ischemia was weak (percent agreement, 71%; kappa [+/- SE], 0.26 +/- 0.07). In a minority of patients (11%) mental stress provoked ischemia in the absence of exercise- or adenosine-induced ischemia. Moreover, in patients who had myocardial ischemia during both stressors, there were significant within-individual differences in the coronary artery distribution of the ischemic regions. MSIMI was more likely to occur in a single-vessel distribution (86%) compared with exercise- or adenosine-induced ischemia (54%). The stressors had moderate agreement if the ischemic region was in the right coronary artery territory (percent agreement, 76%; kappa, 0.52 +/- 0.19) or the left anterior descending coronary artery (percent agreement, 76%; kappa, 0.51 +/- 0.19) and significantly lower agreement in the left circumflex territory (percent agreement, 62%; kappa, 0.22 +/- 0.18).

CONCLUSIONS

Our findings indicate that mental and exercise or adenosine stresses provoke different myocardial ischemic responses. These observations suggest that exercise or adenosine testing may not adequately assess the likelihood of occurrence or severity of MSIMI and that different mechanisms are operative in each condition.

Psychobiology of depression/distress in congestive heart failure

Heart failure affects millions of Americans and new diagnosis rates are expected to almost triple over the next 30 years as our population ages. Affective disorders including clinical depression and anxiety are common in patients with congestive heart failure. Furthermore, the presence of these disorders significantly impacts quality of life, medical outcomes, and healthcare service utilization. In recent years, the literature has attempted to describe potential pathophysiologic mechanisms relating affective disorders and psychosocial stress to heart failure. Several potential mechanisms have been proposed including autonomic nervous system dysfunction, inflammation, cardiac arrhythmias, and altered platelet function. These mechanisms are reviewed in this article. Additional novel mechanisms such as mental stress-induced myocardial ischemia are also discussed.

Do men and women differ on measures of mental stress-induced ischemia?

OBJECTIVE

To consider the effects of gender on ischemia in a larger sample, with broadly defined coronary artery disease (CAD). Mental stress has been shown to cause transient myocardial ischemia in a significant percentage of people with CAD. However, little is known about the effects of mental stress on ischemic processes in women. Most studies to date either had few women or required a positive exercise stress test.

METHODS

Participants (61 women, 93 men; average age = 63 years) had documented CAD (positive stress test, abnormal catheterization even with minimal disease, or previous myocardial infarction). They underwent mental stress testing and radionuclide perfusion imaging (stress/ rest). Cardiac function data were collected and stress was compared with baseline. The data were then submitted to a series of analyses of variance.

RESULTS

A total of 50 (32%) participants exhibited reversible ischemia post psychological stress. This reflects a relative rate of 33% (n = 31 of 93) for men and 31% (n = 19 of 61) for women. No difference between men and women were observed on any measure of hemodynamic functioning (blood pressure, heart rate, or cardiac perfusion).

CONCLUSIONS

Results of this study showed no significant differences between men and women on measures of hemodynamic functioning or cardiac perfusion.

Social support predicts hemodynamic recovery from mental stress in patients with implanted defibrillators

OBJECTIVE

Emotionally stressful events appear to trigger malignant ventricular arrhythmias and myocardial infarction in cardiac patients. However, the physiological pathways linking psychological stress to arrhythmias and adverse disease outcomes remain incompletely understood. In patients with implanted cardioverter-defibrillators (ICD) we investigated the impact of emotions and social support on cardiovascular recovery from mental stress. The hypothesis tested was that psychosocial resources help to maintain adaptive hemodynamic responses to mental stress.

METHODS

In 55 ICD patients we noninvasively measured hemodynamic and autonomic parameters during two sequentially performed mental stress tests (arithmetic and anger recall tests). The cardiovascular data obtained were associated with results from well-validated psychometric self-rating tests for anxiety and depression (HADS), anger (STAXI), and perceived social support (FSozU).

RESULTS

In the rest period after mental stress application the majority of the study participants (82%) showed a rapid fall in cardiac index, arterial blood pressure, and heart rate, as well as an increase in high-frequency heart rate variability, while the remainder had no or unexpected changes in the hemodynamic parameters examined. Patients missing hemodynamic recovery in the post-stress phase reported significantly less social support than normally reacting patients (P<.05). Multivariate logistic regression models confirm that social support is an independent and significant predictor of preserved hemodynamic recovery from mental stress, even after controlling for somatic confounders (multivariate odds ratio 4.1; 95% confidence interval 1.3-12.7; P=.015).

CONCLUSIONS

Our data indicate that in ICD patients better perceived social support is associated with a more pronounced hemodynamic recovery after mental stress.

Coronary artery disease and depression: patients with more depressive symptoms have lower cardiovascular reactivity during laboratory-induced mental stress

OBJECTIVE

To investigate the relationship between symptoms of depression and cardiovascular reactivity during mental stress in patients with coronary artery disease (CAD). Depressive symptoms are common in patients with CAD and are related to an increased risk of cardiac events and death. Some researchers have proposed that negative outcomes in depressed patients with CAD may be related to exaggerated cardiovascular reactivity and psychological stress. However, the data are unclear.

METHODS

Patients with CAD (n = 128; mean age = 64 years) were recruited for this study. Participants underwent psychological stress testing and 2-day (stress/rest) radionuclide imaging. The Beck Depression Inventory (BDI) results were collected at baseline. Cardiac function data were also gathered and stress data were compared with baseline findings.

RESULTS

The change in systolic blood pressure (SBP) from rest to stress was 47 +/- 18 (mean +/- standard deviation) mm Hg, diastolic blood pressure (DBP) = 30 +/- 11 mm Hg, double product difference (DP) = 5887 +/- 3095, and heart rate (HR) = 20 +/- 13 beats/minute (p < .001 for all). The BDI score was 8.7 +/- 5.6. The BDI score was negatively correlated with all hemodynamic variables, although only significant with stress SBP and DP, and HR and DP changes. BDI scores also predicted changes in HR and DP. HR remained significant in regression analyses controlling for other sample characteristics.

CONCLUSIONS

This study showed a negative relationship between depressive symptoms and cardiovascular reactivity to mental stress. In contrast to the mechanism proposed by earlier researchers, this study suggests that decreased cardiovascular reactivity occurs with increased depressive symptomology. The mechanism by which this effect occurs and its clinical significance are still unknown.

C-reactive protein and vulnerability to mental stress-induced myocardial ischemia

Myocardial ischemia provoked in the laboratory during mental stress (MSI) in patients with stable coronary artery disease (CAD) predicts subsequent clinical events. The pathophysiology of MSI differs from that of exercise ischemia, and the mechanisms tying MSI to poor prognosis are not known. C-reactive protein (CRP) is a risk marker for cardiovascular events in patients with CAD, but little is known regarding the relationship of CRP to MSI. The purpose of this study was to examine the association of CRP to risk of MSI in CAD patients. Eighty-three patients with stable CAD underwent simultaneous single-photon emission computed tomography (SPECT) imaging with technetium-99m tetrofosmin myocardial perfusion imaging (MPI) and transthoracic echocardiography (TTE), at rest and during MS induced by laboratory mental stress. Serum CRP levels were measured 24 h after MS. MSI was defined by the presence of a new perfusion defect on SPECT and/or new regional wall motion abnormality on TTE during MS. Of the 83 patients, 30 (36%) developed MSI. There was no difference in gender, sex, BMI, histories of diabetes, hypertension, smoking, lipid profile, medications used (including statins, beta-blockers, ACE inhibitors, and aspirin), or hemodynamic response during MS between those with and without MSI. In univariate logistic regression analysis, each unit (1 mg/L) increase in CRP level was associated with 20% higher risk of MSI (OR 1.2, 95% CI 1.01-1.39, P=.04). This relationship remained in multivariate models. These data suggest that levels of CRP may be a risk marker for MSI in patients with CAD.

C-reactive protein and vulnerability to mental stress-induced myocardial ischemia

Myocardial ischemia provoked in the laboratory during mental stress (MSI) in patients with stable coronary artery disease (CAD) predicts subsequent clinical events. The pathophysiology of MSI differs from that of exercise ischemia, and the mechanisms tying MSI to poor prognosis are not known. C-reactive protein (CRP) is a risk marker for cardiovascular events in patients with CAD, but little is known regarding the relationship of CRP to MSI. The purpose of this study was to examine the association of CRP to risk of MSI in CAD patients. Eighty-three patients with stable CAD underwent simultaneous single-photon emission computed tomography (SPECT) imaging with technetium-99m tetrofosmin myocardial perfusion imaging (MPI) and transthoracic echocardiography (TTE), at rest and during MS induced by laboratory mental stress. Serum CRP levels were measured 24 h after MS. MSI was defined by the presence of a new perfusion defect on SPECT and/or new regional wall motion abnormality on TTE during MS. Of the 83 patients, 30 (36%) developed MSI. There was no difference in gender, sex, BMI, histories of diabetes, hypertension, smoking, lipid profile, medications used (including statins, beta-blockers, ACE inhibitors, and aspirin), or hemodynamic response during MS between those with and without MSI. In univariate logistic regression analysis, each unit (1 mg/L) increase in CRP level was associated with 20% higher risk of MSI (OR 1.2, 95% CI 1.01-1.39, P=.04). This relationship remained in multivariate models. These data suggest that levels of CRP may be a risk marker for MSI in patients with CAD.

Extracellular glycerol regulates the cardiac energy balance in a working rat heart model

We reported previously that glycerol is a substrate for energy production in cardiomyocytes. Increasing glycerol availability results in increased glycerol uptake and its involvement in complex lipid biosynthesis and energy production. This study evaluated the relationship between glycerol supply, energy demand, and intermediary metabolism leading to energy production. The work was performed on isolated rat heart perfused in the working mode. Glycerol concentrations modeled the fasting (0.33 mM) and fed (3.33 mM) states. Cardiac energy demand was modeled by increasing heart rate from 350 to 450 beats/min (bpm). Increasing glycerol supply increased glycerol uptake from 1.4 (350 bpm) to 3.8 (450 bpm) and from 9.7 (350 bpm) to 34.2 (450 bpm) micro mol glycerol/heart in 30 min at 0.33 and 3.33 mM glycerol, respectively. At low glycerol supply, increasing heart rate did not influence the complex lipid synthesis. Conversely, high glycerol concentration increased the complex lipid synthesis by 5- and 30-fold at 350 and 450 bpm, respectively. Increasing glycerol supply and heart rate significantly increased glycerol oxidation rate. Moreover, increasing glycerol supply did not affect glucose oxidation but increased palmitate uptake and significantly decreased its beta-oxidation. Physiological concentrations of glycerol contribute to the cardiac intermediary metabolism, both for energy production and glycerolipid synthesis. Increasing energy demand enhances the requirement and use of glycerol. Glycerol contributes to the regulation of cardiac metabolism and energy balance, mainly by decreasing the contribution of fatty acid oxidation, and may thus represent a new factor in cardiac protection through the reduction of oxygen demand.

Mental stress provokes ischemia in coronary artery disease subjects without exercise- or adenosine-induced ischemia

OBJECTIVES

The purpose of this study was to investigate the possibility that some patients with coronary artery disease (CAD) but negative exercise or chemical stress test results might have mental stress-induced ischemia. The study population consisted solely of those with negative test results.

BACKGROUND

Mental stress-induced ischemia has been reported in 20% to 70% of CAD subjects with exercise-induced ischemia. Because mechanisms of exercise and mental stress-induced ischemia may differ, we studied whether mental stress would produce ischemia in a proportion of subjects with CAD who have no inducible ischemia with exercise or pharmacologic tests.

METHODS

Twenty-one subjects (14 men, 7 women) with a mean age of 67 years and with a documented history of CAD were studied. All subjects had a recent negative nuclear stress test result (exercise or chemical). Subjects completed a speaking task involving role playing a difficult interpersonal situation. A total of 30 mCi 99mTc-sestamibi was injected at one minute into the speech, and imaging was started 40 min later. A resting image obtained within one week was compared with the stress image. Images were analyzed for number and severity of perfusion defects. The summed difference score based on the difference between summed stress and rest scores was calculated. Severity was assessed using a semiquantitative scoring method from zero to four.

RESULTS

Six of 21 (29%) subjects demonstrated reversible ischemia (summed difference score > or =3) with mental stress. No subject had chest pain or electrocardiographic changes during the stressor. Mean systolic and diastolic blood pressure and heart rate all increased between resting and times of peak stress.

CONCLUSIONS

Mental stress may produce ischemia in some subjects with CAD and negative exercise or chemical nuclear stress test results.

A paradigm to investigate the self-regulation of cocaine administration in humans

INTRODUCTION

Current laboratory paradigms of human cocaine administration generally dictate the timing of drug access in ways that may limit assessing aspects of cocaine-taking behavior. Patient-controlled analgesia (PCA) methods, which allow individuals less restricted access to narcotic (i.e., opiate) analgesics, have proven safe and clinically effective for self-regulated treatment of pain. The current study assessed the feasibility, safety, and validity of a model of ad libitum cocaine self-administration, in which participants self-selected the timing of cocaine infusions, using PCA techniques.

METHODS

Eight nontreatment seeking, otherwise medically healthy, experienced cocaine users participated in a double-blind, placebo-controlled, escalating-dose regimen of intravenous cocaine (0, 8, 16, and 32 mg per 70 kg) on 4 test days, during which time participants had 2 h of access to cocaine via manual presses of a corded PCA pump button under a fixed ratio 1: time-out 5-min schedule.

RESULTS

Procedures were well-tolerated by participants, and no significant adverse events were noted. Measures of cocaine self-administration (e.g., number of responses and interinfusion intervals) indicated a significant main effect of cocaine dose, consistent with predicted dose-response relationships (i.e., decreasing responses and increasing interinfusion intervals with increasing injection dose). Participants appeared to regulate their cocaine intake in a carefully controlled manner, using considerably less cocaine (about half) that permitted by pump loading, PCA parameters, and session duration.

CONCLUSIONS

Data from this study support the validity of our PCA paradigm. Moreover, results suggest the apparent feasibility and safety of allowing experienced users to self-select the timing of cocaine infusions to intervals as short as 5 min. Such procedures may enhance our ability to identify effective pharmacological treatments for cocaine addiction.

Emotions in everyday life: an ambulatory monitoring study with female students

Additional heart rate as an indicator of emotional arousal was monitored throughout the day with a special ambulatory device. Fifty female students received acoustic feedback every 10-20 min. The feedback was based either on events (additional heart rate present) or was random without additional heart rate. Following the feedback the subjects were asked to disclose their emotions. The following emotions were listed on the display of the monitoring device: no emotion, happiness, anger, anxiety/fear, sadness, surprise, and disgust. The frequency and quality of the emotions were not different between event-related and random feedbacks, indicating that the subjects were not able to discriminate between events with and without additional heart rate correctly. Accordingly, the physiological profiles of the differing emotions compared to conditions with "no emotion" were equivocal. The psychological ratings of excitement and enjoyment, however, came up to expectations. The results show that cognitive schemata and personality dimensions are more important in emotion perception than physiological activation.

Comparison of mental stress-induced myocardial ischemia in coronary artery disease patients with versus without left ventricular dysfunction

To examine the susceptibility to myocardial ischemia with mental stress in patients who have coronary artery disease and normal left ventricular (LV) function versus those who have impaired LV function, we examined 58 patients who had coronary artery disease, including 22 who had normal LV function (ejection fraction >/=50%), 16 who had mild to moderate LV dysfunction (ejection fraction 30% to 50%), and 20 who had severe LV dysfunction (ejection fraction </=30%) and underwent bicycle and mental stress testing with myocardial perfusion scintigraphy on consecutive days in random order. Ischemia was assessed based on summed difference scores in regional rest versus stress myocardial perfusion and defined as a summed difference score >3. At comparable double products across the 3 groups, ischemia was induced with mental stress more frequently in patients who had severe LV dysfunction (50%) than in those who had normal LV function (9%; p <0.01). The frequency of exercise-induced ischemia was different only between those who had mild/moderate LV dysfunction and those who had normal LV function (56% vs 18%, respectively, p <0.05). The pattern of mental stress versus exercise ischemia differed between groups (p <0.02): there was a higher prevalence of mental stress ischemia versus exercise ischemia in patients who had severe LV dysfunction (p = 0.06), a marginally higher prevalence of exercise versus mental stress ischemia in those who had moderate LV dysfunction (p = 0.07), and no difference in mental stress versus exercise ischemia in those who had normal LV function. Thus, at comparable double products during mental stress and similar extent of coronary artery disease, ischemia with mental stress was induced more frequently in patients who had severe LV dysfunction than in those who had normal LV function. These data suggest that mental stress ischemia may be of particular clinical importance in patients who have coronary artery disease and LV dysfunction.