Triggers, acute risk factors and vulnerable plaques: the lexicon of a new frontier

Feasibility of FDG imaging of the coronary arteries: comparison between acute coronary syndrome and stable angina

OBJECTIVES

This study tested the hypothesis that fluorodeoxyglucose (FDG) uptake within the ascending aorta and left main coronary artery (LM), measured using positron emission tomography (PET), is greater in patients with recent acute coronary syndrome (ACS) than in patients with stable angina.

BACKGROUND

Inflammation is known to play an important role in atherosclerosis. Positron emission tomography imaging with (18)F-FDG provides a measure of plaque inflammation.

METHODS

Twenty-five patients (mean age 57.9 +/- 9.8 years, 72% male, 10 ACS, and 15 stable angina) underwent cardiac computed tomographic angiography and PET imaging with (18)F-FDG after invasive angiography. Images were coregistered, and FDG uptake was measured at locations of interest for calculation of target-to-background ratios (TBR). Additionally, FDG uptake was measured at the site of the lesion deemed clinically responsible for the presenting syndrome (culprit) by virtue of locating the stent deployed to treat the syndrome.

RESULTS

The FDG uptake was higher in the ACS versus the stable angina groups in the ascending aorta (median [interquartile ranges] TBR 3.30 [2.69 to 4.12] vs. 2.43 [2.00 to 2.86], p = 0.02), as well as the LM (2.48 [2.30 to 2.93] vs. 2.00 [1.71 to 2.44], p = 0.03, respectively). The TBR was greater for culprit lesions associated with ACS than for lesions stented for stable coronary syndromes (2.61 vs. 1.74, p = 0.02). Furthermore, the TBR in the stented lesions (in ACS and stable angina groups) correlated with C-reactive protein (r = 0.58, p = 0.04).

CONCLUSIONS

This study shows that in patients with recent ACS, FDG accumulation is increased both within the culprit lesion as well as in the ascending aorta and LM. This observation suggests inflammatory activity within atherosclerotic plaques in acute coronary syndromes and supports intensification of efforts to refine PET methods for molecular imaging of coronary plaques.

Cholesterol crystals piercing the arterial plaque and intima trigger local and systemic inflammation

The response to arterial wall injury is an inflammatory process, which over time becomes integral to the development of atherosclerosis and subsequent plaque instability. However, the underlying injurious agent, critical to this process, has not received much attention. In this review, a model of plaque rupture is hypothesized with two stages of inflammatory activity. In stage I (cholesterol crystal-induced cell injury and apoptosis), intracellular cholesterol crystals induce foam cell apoptosis, setting up a vicious cycle by signaling more macrophages, resulting in accumulation of extra cellular lipids. This local inflammation eventually leads to the formation of a semi-liquid, lipid-rich necrotic core of a vulnerable plaque. In stage II (cholesterol crystal-induced arterial wall injury), the saturated lipid core is now primed for crystallization, which can manifest as a clinical syndrome with a systemic inflammation response. Cholesterol crystallization is the trigger that causes core expansion, leading to intimal injury. We recently demonstrated that when cholesterol crystallizes from a liquid to a solid state, it undergoes volume expansion, which can tear the plaque cap. This observation of cholesterol crystals perforating the cap and intimal surface was made in the plaques of patients who died with acute coronary syndrome. We have also demonstrated that several agents (ie, statins, aspirin, and ethanol) can dissolve cholesterol crystals and may be exerting their immediate benefits by this direct mechanism. Also, because recent studies have demonstrated that high-sensitivity C-reactive protein may be a reliable marker in selecting patients for statin therapy, it could reflect the presence of intimal injury by cholesterol crystals. This was demonstrated in an atherosclerotic rabbit model. Therefore, we propose that cholesterol crystallization could help explain in part both local and systemic inflammation associated with atherosclerosis.

Update on Clinical Imaging of Coronary Plaque in Acute Coronary Syndrome

Current evidence suggests that understanding coronary artery disease extends beyond identifying and treating traditional risk factors. Progression of coronary plaque contributes to the development of acute coronary syndrome (ACS). In this article, we reviewed current literature for modalities to image coronary plaque as well as discussed the role of emerging techniques that can improve our understanding of the pathophysiology of ACS. Key words: Coronary disease, Myocardial infarction, Vulnerable plaque

Current status of vulnerable plaque detection

Critical coronary stenoses have been shown to contribute to only a minority of acute coronary syndromes (ACS) and sudden cardiac death. Autopsy studies have identified a subgroup of high-risk patients with disrupted vulnerable plaque and modest stenosis. Consequently, a clinical need exists to develop methods to identify these plaques prospectively before disruption and clinical expression of disease. Recent advances in invasive and noninvasive imaging techniques have shown the potential to identify these high-risk plaques. The anatomical characteristics of the vulnerable plaque such as thin cap fibroatheroma and lipid pool can be identified with angioscopy, high frequency intravascular ultrasound, intravascular MRI, and optical coherence tomography. Efforts have also been made to recognize active inflammation in high-risk plaques using intravascular thermography. Plaque chemical composition by measuring electromagnetic radiation using spectroscopy is also an emerging technology to detect vulnerable plaques. Noninvasive imaging with MRI, CT, and PET also holds the potential to differentiate between low and high-risk plaques. However, at present none of these imaging modalities are able to detect vulnerable plaque neither has been shown to definitively predict outcome. Nevertheless in contrast, there has been a parallel development in the physiological assessment of advanced atherosclerotic coronary artery disease. Thus recent trials using fractional flow reserve in patients with modest non flow-limiting stenoses have shown that deferral of PCI with optimal medical therapy in these patients is superior to coronary intervention. Further trials are needed to provide more information regarding the natural history of high-risk but non flow-limiting plaque to establish patient-specific targeted therapy and to refine plaque stabilizing strategies in the future.

Triggers and the onset of acute myocardial infarction

The onset of acute myocardial infarction (AMI) is a complex interplay of internal circadian factors and external physical and emotional triggers. These interactions may lead to rupture of an often nonocclusive vulnerable atherosclerotic coronary plaque with subsequent formation of an occlusive thrombus. The onset of AMI has a distinct pattern, with peak incidence within the first few hours after awakening, on certain days of the week, and in the winter months. Physical and emotional stresses are important triggers of acute cardiovascular events including AMI. Triggering events, internal changes, and external factors vary among different geographical, environmental, and ethnic regions. Life-style changes, pharmacotherapy, and psychologic interventions may potentially modify the response to, and protect against the effects of triggering events.

The percutaneous assessment of regional and acute coronary hot unstable plaques by thermographic evaluation (PARACHUTE) study: a prospective reproducibility and prognostic clinical study using thermography to predict future ischemic cardiac events

Intravascular thermography is currently being considered as a valuable tool in assessing macrophage-rich plaques. Since it is unknown what the prognostic value is of non-obstructive atherosclerotic plaques showing temperature heterogeneity, we designed the PARACHUTE study, a prospective, reproducibility, and prognostic clinical study using thermography in patients presenting with an unstable coronary syndrome. The primary endpoint of the study is the predictive value of temperature heterogeneity towards the occurrence of ischemic coronary events and hospitalization for ischemia and/or angina. The secondary endpoints are the predictive value of high-risk plaques associated with the development of future cardiac events, assessment of safety of the procedure, assessment of temperature reproducibility and heterogeneity in coronary arteries, as defined by the total thermal burden towards the occurrence of any cardiac event. Based on an event rate of death and myocardial infarction at 1 year of 10%, a sample size of 260 patients with presumed coronary artery disease, and positive troponin level who are scheduled to undergo an intervention will be included. All three main epicardiac vessels will undergo angiography and thermography at baseline after revascularization of the flow-limiting vessel. At 12 months, angiography of all vessels and thermography of the vessel with the highest thermographic burden will be performed. Independent core laboratories will assess outcomes and a clinical endpoint committee will assess clinical events.

Cold-related cardiac mortality in King County, Washington, USA 1980–2001

BACKGROUND

Studies have shown that cardiac deaths increase during the winter months and that death rates can be tightly predicted from temperature rather than other atmospheric phenomena such as barometric pressure, humidity, or pollution.

AIM

The object of this study is to examine the possible relationship between temperature and cardiac death rates in King County, Washington, USA and suggest possible public health measures that can decrease the number of cardiac deaths associated with cold exposure.

SUBJECTS AND METHODS

State death records show that 62,125 total out-of-hospital cardiac-related deaths among persons 55 years and older occurred in King County between 1980 and 2001. We use Poisson regression to examine the association between same-day daily average temperature and death rate after adjusting for seasonal effects.

RESULTS

We identified a significant negative association between daily average temperature and cardiac mortality among persons over 55 years of age. A 5 degrees C increase in temperature was associated with a decrease in death rate by a factor of 0.971 (95% CI: 0.961, 0.982).

CONCLUSION

Cold temperatures may be an important triggering factor in bringing on the onset of life-threatening cardiac events, even in regions with relatively mild winters. Public health efforts stressing cold exposure while out of doors may play a prominent role in encouraging a reduction in cold stress, especially among seniors and those already at higher risk of cardiac death.

Ozone and cardiovascular injury

Air pollution is increasingly recognized as an important and modifiable determinant of cardiovascular diseases in urban communities. The potential detrimental effects are both acute and chronic having a strong impact on morbidity and mortality. The acute exposure to pollutants has been linked to adverse cardiovascular events such as myocardial infarction, heart failure and life-threatening arrhythmias. The long-terms effects are related to the lifetime risk of death from cardiac causes. The WHO estimates that air pollution is responsible for 3 million premature deaths each year. The evidence supporting these data is very strong nonetheless, epidemiologic and observational data have the main limitation of imprecise measurements. Moreover, the lack of clinical experimental models makes it difficult to demonstrate the individual risk. The other limitation is related to the lack of a clear mechanism explaining the effects of pollution on cardiovascular mortality. In the present review we will explore the epidemiological, clinical and experimental evidence of the effects of ozone on cardiovascular diseases.

The pathophysiologic consequences of air pollutant exposures have been extensively investigated in pulmonary systems, and it is clear that some of the major components of air pollution (e.g. ozone and particulate matter) can initiate and exacerbate lung disease in humans [1]. It is possible that pulmonary oxidant stress mediated by particulate matter and/or ozone (O3) exposure can result in downstream perturbations in the cardiovasculature, as the pulmonary and cardiovascular systems are intricately associated, and it is well documented that specific environmental toxins (such as tobacco smoke [2]) introduced through the lungs can initiate and/or accelerate cardiovascular disease development. Indeed, several epidemiologic studies have proved that there is an association between PM and O3 and the increased incidence of cardiovascular morbidity and mortality [3]. Most of the evidence comes from studies of ambient particles concentrations. However, in Europe and elsewhere, the air pollution profile has gradually changed toward a more pronounced photochemical component. Ozone is one of the most toxic components of the photochemical air pollution mixture. Indeed, the biological basis for these observations has not been elucidated.

In the present review, the role of ozone as chemical molecule will be firstly considered. Secondly, pathogenetic mechanisms connecting the atmospheric ozone level and cardiovascular pathology will be examined. Thirdly, the literature relating hospitalization frequency, morbidity and mortality due to cardiovascular causes and ozone concentration will be studied. The correlation between ozone level and occurrence of acute myocardial infarction will be eventually discussed.

Therapy for triggered acute risk prevention: a study of feasibility

BACKGROUND

Heavy physical exertion, emotional stress, heavy meals and respiratory infection transiently increase the risk of myocardial infarction, sudden death and stroke, however it remains uncertain how to use this information for disease prevention.

AIMS

We determined the feasibility of taking targeted medication for the hazard duration of a triggering activity to reduce risk.

METHODS

After a run-in training period over 1 month, 17 healthy subjects recorded for 1 month all episodes of physical and emotional stress, heavy meal and respiratory infection. For each episode, they were instructed to take either aspirin 100mg and propranolol 10mg (for physical exertion and emotional stress) or aspirin 100mg alone (for respiratory infection and heavy meal) and record adherence with taking medication. Subjects performed exertion while wearing a heart rate monitor, once during the run-in period, and once 30 min after taking propranolol and aspirin.

RESULTS

Based on study diary subjects reliably documented triggers with 94% adherence. Designated medication was also reliably taken, with 88% adherence. Propranolol taken prior to exertion resulted in a lower peak heart rate (128+/-38 versus 149+/-21, p<0.01) compared to similar exercise during the run-in period. Over two-thirds (71%) of subjects considered that it was feasible to continue taking medication in this manner.

CONCLUSIONS

The study indicates that potential triggers of acute cardiovascular disease can be reliably identified, and it is feasible and acceptable to take targeted medication at the time of these triggers. These findings encourage further investigation of the potential role of this therapeutic strategy.

Exaggerated morning blood pressure surge and cardiovascular events. A 5-year longitudinal study in normotensive and well-controlled hypertensive elderly

Cardiovascular events (CE) occur most frequently in the morning hours in hypertensive subjects. We studied the association between the morning blood pressure (BP) surge and CE in prognosis of 10 normotensive and 32 well-controlled hypertensive elderly, in whom ambulatory BP monitoring was performed and who were followed prospectively for 5 years. The morning surge (MS) of BP was calculated as mean systolic BP during 2h after awakening--mean systolic BP during 1h that included the lowest sleep BP. During an average of 60 months, five CE occurred. When the patients were divided into two groups according to MS, those in the top terzile (MS group; MS> or =34 mmHg, n=14) had a higher prevalence of CE (5 versus 0, p=0.001) during the follow-up period, than the others (non-MS group; MS<34 mmHg, n=28). The logistic regression analysis showed the MS sleep-trough surge as predictive variable of CE (odds ratio, OR=0.794, p=0.022). In conclusion, in older normotensives and well-controlled hypertensives, a higher BP MS is associated with vascular risk independently of clinical and ambulatory BP. Reduction of the MS could thus be a therapeutic target for preventing vascular events also in non-hypertensive patients.

Endothelial dysfunction: associations with exposure to ambient fine particles in diabetic individuals

BACKGROUND

Exposure to fine airborne particulate matter [< or =2.5 microm in aerodynamic diameter (PM(2.5))] has been associated with cardiovascular and hematologic effects, especially in older people with cardiovascular disease. Some epidemiologic studies suggest that adults with diabetes also may be a particularly susceptible population.

OBJECTIVES

The purpose of this study was to analyze the short-term effects of ambient PM(2.5) on markers of endothelial function in diabetic volunteers.

METHODS

We conducted a prospective panel study in 22 people with type 2 diabetes mellitus in Chapel Hill, North Carolina (USA), from November 2004 to December 2005. We acquired daily measurements of PM(2.5) and meteorologic data at central monitoring sites. On 4 consecutive days, we measured endothelial function by brachial artery ultrasound in all participants and by pulsewave measurements in a subgroup. Data were analyzed using additive mixed models with a random participant effect and adjusted for season, day of the week, and meteorology.

RESULTS

Flow-mediated dilatation decreased in association with PM(2.5) during the first 24 hr, whereas small-artery elasticity index decreased with a delay of 1 and 3 days. These PM(2.5)-associated decrements in endothelial function were greater among participants with a high body mass index, high glycosylated hemoglobin A1c, low adiponectin, or the null polymorphism of glutathione S-transferase M1. However, high levels of myeloperoxidase on the examination day led to strongest effects on endothelial dysfunction.

CONCLUSIONS

These data demonstrate that PM(2.5) exposure may cause immediate endothelial dysfunction. Clinical characteristics associated with insulin resistance were associated with enhanced effects of PM on endothelial function. In addition, participants with greater oxidative potential seem to be more susceptible.

Chronic diseases and natural hazards: impact of disasters on diabetic, renal, and cardiac patients

BACKGROUND

Inadequately controlled chronic diseases may present a threat to life and well-being during the emergency response phase of disasters. Chronic disease exacerbations (CDE) account for one of the largest patient populations during disasters, and patients are at increased risk for adverse outcomes.

OBJECTIVE

The objective of this study was to assess the burden of chronic renal failure, diabetes, and cardiovascular disease during disasters due to natural hazards, identify impediments to care, and propose solutions to improve the disaster preparation and management of CDE.

METHODS

A thorough search of the PubMed, Ovid, and Medline databases was performed. Dr. Miller's personal international experiences treating CDE after disasters due to natural hazards, such as the 2005 Kashmir earthquake, are included.

DISCUSSION

Chronic disease exacerbations comprise a sizable disease burden during disasters related to natural hazards. Surveys estimate that 25-40% of those living in the regions affected by hurricanes Katrina and Rita lived with at least one chronic disease. Chronic illness accounted for 33% of visits, peaking 10 days after hurricane landfall. The international nephrology community has responded to dialysis needs by forming a well-organized and effective organization called the Renal Disaster Relief Task Force (RDRTF). The response to the needs of diabetic and cardiac patients has been less vigorous. Patients must be familiar with emergency diet and renal fluid restriction plans, possible modification of dialysis schedules and methods, and rescue treatments such as the administration of kayexalate. Facilities may consider investing in water-independent extracorporeal dialysis techniques as a rescue treatment. In addition to patient databases and medical alert identification, diabetics should maintain an emergency medical kit. Diabetic patients must be taught and practice the carbohydrate counting technique. In addition to improved planning, responding agencies and organizations must bring adequate supplies and medications to care for diabetic, cardiac, and renal patients during relief efforts.

CONCLUSIONS

By recognizing and addressing impediments to the care of chronic disease exacerbations after natural disasters, the quality, delivery, and effectiveness of the care provided to diabetic patients during relief efforts can be improved.

Acute myocardial infarction in a 24 year-old man possibly associated with sibutramine use

Sibutramine is an anti-obesity drug, which acts by inhibiting neuronal re-uptake of noradrenaline and serotonin. Although the most frequently seen effect of sibutramine on cardiovascular system is an increase in blood pressure and pulse rate, rare but severe side effects such as sibutramine-induced ventricular arrhythmias, heart failure and cardiovascular disease-related death are also reported. We describe a 24 year-old man with low atherosclerotic risk profile who had acute myocardial infarction possibly associated with sibutramine use.

A cold shock response triggering acute myocardial infarction

Acute risk factors are activities and events that suddenly and transiently increase the risk of acute cardiac events, as reported recently in International Journal of Cardiology. It has already been reported that sudden submersion in cold water may provoke myocardial infarction in both subjects with atherosclerotic coronary disease and young people with angiographically normal coronary arteries. We report a case of an acute myocardial infarction triggered by sudden exposure to cold air temperature extreme in a young person with acutely occluded proximal part of the left anterior descending coronary artery and normal other coronary arteries who had extreme obesity and cigarette smoking as cardiovascular risk factors. Our report indicates that the sudden cold exposure and the resulting cold shock response may provoke acute myocardial infarction in young susceptible patients.

Apical ballooning syndrome (Tako-Tsubo or stress cardiomyopathy): a mimic of acute myocardial infarction

Apical ballooning syndrome (ABS) is a unique reversible cardiomyopathy that is frequently precipitated by a stressful event and has a clinical presentation that is indistinguishable from a myocardial infarction. We review the best evidence regarding the pathophysiology, clinical features, investigation, and management of ABS. The incidence of ABS is estimated to be 1% to 2% of patients presenting with an acute myocardial infarction. The pathophysiology remains unknown, but catecholamine mediated myocardial stunning is the most favored explanation. Chest pain and dyspnea are the typical presenting symptoms. Transient ST elevation may be present on the electrocardiogram, and a small rise in cardiac troponin T is invariable. Typically, there is hypokinesis or akinesis of the mid and apical segments of the left ventricle with sparing of the basal systolic function without obstructive coronary lesions. Supportive treatment leads to spontaneous rapid recovery in nearly all patients. The prognosis is excellent, and a recurrence occurs in <10% of patients. Apical ballooning syndrome should be included in the differential diagnosis of patients with an apparent acute coronary syndrome with left ventricular regional wall motion abnormality and absence of obstructive coronary artery disease, especially in the setting of a stressful trigger.

Interleukin-18 and stress

Interleukin-18 (IL-18) is a pro-inflammatory cytokine believed to play a role in a variety of conditions and diseases including infections, autoimmunity, cancer, diabetes and atherosclerosis. IL-18 is also a possible contributor to the sickness syndrome by inducing anorexia and sleep. Originally recognized to be produced by cells of the immune system, IL-18 is also found in endocrine tissues, including the adrenal and the pituitary glands, and in the central nervous system where it is produced by microglial and ependymal cells as well as by neurons of the medial habenular nucleus. IL-18 is produced constitutively and its levels can increase during infection but also during stress in the absence of an exogenous stimulus. IL-18 levels are elevated by activation of the hypothalamic-pituitary-adrenal (HPA) axis in a tissue specific way via differential promoter and splicing usage, and may be down-regulated by the activation of the para-sympathetic system. This suggested the possibility that IL-18 may participate in the regulation of the HPA axis or that it may have a role in mediating the CNS dependent effects on the susceptibility to or the progression of diseases. This review summarizes the evidence linking stress and IL-18 and discusses the possible implication of the neuro-immuno-modulatory action of IL-18.

Imaging techniques for the vulnerable coronary plaque

The goal of this article is to illustrate the main invasive and noninvasive diagnostic modalities to image the vulnerable coronary plaque, which is responsible for acute coronary syndrome. The main epidemiologic and histological issues are briefly discussed in order to provide an adequate background. Comprehensive coronary atherosclerosis imaging should involve visualization of the entire coronary artery tree and plaque characterization, including three-dimensional morphology, relationship with the lumen, composition, vascular remodelling and presence of inflammation. No single technique provides such a comprehensive description, and no available modality extensively identifies the vulnerable plaque. In particular, we describe multislice computed tomography, which at present seems to be the most promising noninvasive tool for an exhaustive image-based quantification of coronary atherosclerosis.

Patient Education: The Tapestry of Emotion and Exercise

In everyday practice, it is important to realize that the tapestry of emotion and body, via the conduit of exercise, is closely linked. Anxiety is reduced following exercise. Depressed patients who exercise maintain their gains longer than those who do not. Exercise is an effective means and adjunct to medical therapy to treat both anxiety and depressive disorders, often present as comorbid disorders.

Acute risk factors for myocardial infarction

Increased knowledge concerning the triggering of acute cardiovascular diseases has yielded a change in philosophical approach to this field. During the last decade, clinical evidence suggested that the term acute risk factors can be used for the activities and events that suddenly and transiently increase the risk of acute cardiac diseases. External triggers, such as heavy physical activity, emotional stress, eating, cold or heat exposure, coffee or alcohol consumption, cocaine or marijuana use and sexual intercourse are recognized as most important acute risk factors. It is likely that the morning hours may be considered as an endogenous, external triggering independent acute risk factor related to physiological sympathetic arousal. The features of triggering have been best described for an acute myocardial infarction whose moment of onset appears to be the result of a dynamic interaction between an endogenous response to acute risk factors and patient vulnerability. In this article, pathophysiological changes implicated as internal triggering mechanisms are summarized and the terms sympathetic and parasympathetic triggering patterns are introduced. A highly individual approach tailored both to protect against acute risk factors and to reduce patient vulnerability could provide a more complete protection from myocardial infarction and other coronary incidents. Lifestyle modifications, regular physical activity and adequate drug regimens may at least prove able to defer the occurrence of coronary thrombosis, thereby providing time for the development of collateral vessels, plaque stabilization or invasive/surgical treatment.

Gender differences in the link between childhood socioeconomic conditions and heart attack risk in adulthood

A growing body of evidence shows that childhood socioeconomic status (SES) is predictive of disease risk in later life, with those from the most disadvantaged backgrounds more likely to experience poor adult-health outcomes. Most of these studies, however, are based on middle-aged male populations and pay insufficient attention to the pathways between childhood risks and specific adult disorders. This article examines gender differences in the link between childhood SES and heart attack risk trajectories and the mechanisms by which early environments affect future disease risk. By using methods that model both latent and path-specific influences, we identify heterogeneity in early life conditions and human, social, and health capital in adulthood that contribute to diverse heart attack risk trajectories between and among men and women as they age into their 60s and 70s. We find that key risk factors for heart attack operate differently for men and women. For men, childhood SES does not differentiate those at low, increasing, and high risk for heart attack. In contrast, women who grew up without a father and/or under adverse economic conditions are the most likely to experience elevated risk for heart attack, even after we adjust for the unequal distribution of working and living conditions, social relationships, access to health care, and adult lifestyle behaviors that influence health outcomes.

Physiological and cognitive effects of expressive dissonance

Emotional well-being depends in part on affect modulation. The present study extends research on emotion regulation by assessing the physiological and cognitive effects of a novel response-focused regulation strategy, termed 'expressive dissonance.' Expressive dissonance refers to the incongruence between an emotional state (e.g., sadness) and a behavioral expression (e.g., a smile). Fifty-five participants watched a series of sad film clips in which they were asked to either naturally watch or express the opposite of what they were feeling. Results suggest that persons using the expressive dissonant strategies evidenced greater sympathetic arousal and performed worse on subsequent memory tasks than persons in the natural-watch conditions.

The Clinical Application of Metabolic Therapy for Cardiovascular Disease

Metabolic therapy involves the administration of a substance normally found in the body to enhance a metabolic reaction within the cell. This may be achieved in two ways. Firstly, for some systems a substance can be given to achieve greater than normal levels in the body so as to drive an enzymic reaction in a preferred direction. Secondly, metabolic therapy may be used to correct an absolute or relative deficiency of a cellular component. Thus, metabolic therapy differs greatly from most standard cardiovascular pharmacologic therapies such as the use of ACE Inhibitors, beta-blockers, statins and calcium channel antagonists that are given to block rather than enhance cellular processes.

Mental stress and coronary artery disease: a multidisciplinary guide

Research suggests that acute and chronic stress are risk factors for the development and progression of coronary artery disease. Much of this work is multidisciplinary, using unfamiliar concepts deriving from disciplines other than cardiology and medicine. This article addresses and clarifies, for the cardiologist, some of the key concepts and issues in this area and provides an overview of evidence linking acute and chronic stress to cardiac pathology. Areas addressed include definitions and measurement of mental stress, methodological issues in stress research, and distinctions between stress and variables such as personality, emotion, and depression. Mental stress is a multifactorial process involving the environment, individual experiences and coping, and a set of neuroendocrine, autonomic, cardiovascular, and other systemic physiologic responses. There are difficulties identifying a single consensus physiologic stress measure because of individual differences in perceptions and physiologic response patterns. Nonetheless, important associations exist between mental stress and clinically relevant cardiovascular end points. As multidisciplinary research in this area continues, one major goal is the better integration of psychosocial knowledge and measures with cardiology research and practice.

Stress cardiovascular/autonomic interactions in mice

Studies evaluated the role of the autonomic nervous system in the cardiovascular response to stress using radiotelemetric blood pressure (BP) recording coupled with autoregressive spectral analysis. Conscious male C57/BL6 mice with carotid arterial telemetric catheters were exposed to acute episodes of shaker stress before and after administration of cholinergic, beta1-adrenergic and alpha1-adrenergic receptor antagonists. Pulse interval (PI) and systolic arterial pressure (SAP) were analyzed for variance and the low frequency (LF: 0.1-1.0 Hz) and high frequency (HF: 1-5 Hz) spectral components. Stress (5 min) increased BP and heart rate (HR) as well as PI and SAP variability. PI variance increased from 41+/-6 to 75+/-14 ms2 while SAP variance increased from 25+/-5 to 55+/-9 mm Hg2. Autonomic blockade had specific effects on stress-induced changes in PI and SAP and their respective variability. Atropine reduced the tachycardia and abolished the increase in PI variance and its LF component. Data documents that in mice the cholinergic system is fundamental for the maintenance of HR variability. Atropine had no effects on the BP responses, either the increase in SAP or the variance associated with stress. Atenolol blocked the increase in PI and SAP variability induced by stress. Prazosin reduced the tachycardia produced by stress and blocked the increase in PI (only LF) and SAP variability. Using quantitative spectral analysis of telemetrically collected BP data in mice along with pharmacological antagonism, we were able to accurately determine the role of autonomic input in the mediation of the stress response. Data verify the role of sympathetic/parasympathetic balance in stress-induced changes in HR, BP and indices of variance.

Arterial wall cholesterol content is a predictor of development and severity of arterial thrombosis

BACKGROUND

It is unclear if total cholesterol content contributes to the severity of cardiovascular events by affecting the amount of thrombosis. This study evaluated relationships between cholesterol levels and the amount of thrombosis in an atherosclerotic rabbit model of plaque disruption and thrombosis.

METHODS

Three groups of NZW rabbits were used: normal rabbits (Group I, n = 4); atherosclerotic rabbits (Group II, n = 4); and atherosclerotic rabbits with pharmacologically triggered thrombosis (Group III, n = 16). Atherosclerosis was induced by feeding a cholesterol enriched diet and balloon deendothelialization. At post-mortem, platelet-rich thrombus and arterial wall cholesterol were quantified and histology performed by light and electron microscopy.

RESULTS

Arterial wall cholesterol was strongly correlated to serum cholesterol in all groups (r = 0.94, p < 0.0001). There was a significant correlation between the thrombus surface area with arterial wall cholesterol in Group III (r = 0.71, p < 0.002). Serum cholesterol, arterial wall cholesterol, and thrombus surface area were all significantly correlated but only arterial wall cholesterol was an independent predictor of thrombosis. A threshold specific for this model was noted for serum and arterial cholesterol levels above which thrombosis consistently occurred.

CONCLUSIONS

Arterial wall cholesterol was strongly correlated to serum cholesterol and thrombosis severity. Serum cholesterol, arterial wall cholesterol and thrombus surface area were all integrally related.A model of plaque disruption and thrombosis was used to demonstrate a correlation between serum and arterial wall cholesterol (r = 0.94; p < 0.0001); arterial wall cholesterol and the amount of thrombosis (surface area; r = 0.71, p < 0.002). A threshold of serum and arterial cholesterol was determined at which thrombosis occurred in this model.

Pre-operative Preparation for Cardiac Surgery Utilising a Combination of Metabolic, Physical and Mental Therapy

Cardiac surgery represents major metabolic, physical and mental stresses associated with an increased production of reactive oxygen species. These stresses may hamper post-operative recovery, increasing hospitalisation times and operative mortality. We conducted a quality assurance and feasibility study to evaluate and monitor the safety and efficacy of a new program of combined pre-operative metabolic (enhanced antioxidant), physical and mental therapy to counter these stresses prior to cardiac surgery.

METHODS

Sixteen cardiac surgery patients received metabolic therapy consisting of the antioxidants coenzyme Q(10) (CoQ(10)) (300 mg) and alpha-lipoic acid (300 mg), combined with magnesium orotate (1200 mg), and omega-3 fatty acids (3g) given daily for a mean 36+/-7 days up until the day of operation. Patients also received a regimen of physical therapy incorporating non-exhaustive, light exercise and stretching techniques. Mental therapy in the form of stress reduction, relaxation and music was also provided. Blood levels of CoQ(10) and malondialdehyde (MDA) were measured and a quality of life (QoL) questionnaire (SF-36) was administered before, after the program and 1 month after surgery. A patient satisfaction survey was conducted at six weeks post-operatively.

RESULTS

During the pre-operative period, treated patients (n=16) showed significant improvements in QoL composite scores, physical (33.5+/-4.1 to 41.0+/-4.5, p=0.005) and mental (44.3+/-4.5 to 54.1+/-5.3, p=0.006). CoQ(10) levels increased from 725.6+/-96.1 nmol/l to 3019.9+/-546.4 nmol/l (p=0.006), MDA levels decreased from 2.2+/-0.9 microM to 1.4+/-0.7 microM (p=0.013) and systolic blood pressure decreased from 140+/-4.0 mmHg to 132+/-3.0 mmHg (p=0.002). One month after surgery the treated group (n=14) demonstrated significant improvements from pre-operative baseline in QoL composite scores, physical (38.9+/-4.0 to 57.9+/-5.4, p=0.01) and mental (50.3+/-5.6 to 69.3+/-4.8, p=0.03) compared to a previously reported similar group of cardiac surgery patients (n=74) whose physical and mental scores decreased from 43.0 to 42.8 (p=0.05) and 53.8 to 49.8, respectively (p=0.05).

CONCLUSION

These preliminary results suggest that a program of combined metabolic, physical and mental preparation before cardiac surgery is safe, feasible and may improve quality of life, lower systolic blood pressure, reduce levels of oxidative stress and thus has the potential to enhance post-operative recovery.

Can we identify sources of fine particles responsible for exercise-induced ischemia on days with elevated air pollution? The ULTRA study

Epidemiologic studies have shown that ambient particulate matter (PM) has adverse effects on cardiovascular health. Effective mitigation of the health effects requires identification of the most harmful PM sources. The objective of our study was to evaluate relative effects of fine PM [aerodynamic diameter0.1 mV, with odds ratios at 2-day lag of 1.53 [95% confidence interval (CI), 1.19-1.97] and 1.11 (95% CI, 1.02-1.20) per 1 microg/m3, respectively. In multipollutant models, where we used indicator elements for sources instead of source-specific PM2.5, only absorbance (elemental carbon), an indicator of local traffic and other combustion, was associated with ST segment depressions. Our results suggest that the PM fraction originating from combustion processes, notably traffic, exacerbates ischemic heart diseases associated with PM mass.

Natural and unnatural triggers of myocardial infarction

Previous analyses have suggested that factors that stimulate the sympathetic nervous system and catecholamine release can trigger acute myocardial infarction. The wake-up time, Mondays, winter season, physical exertion, emotional upset, overeating, lack of sleep, cocaine, marijuana, anger, and sexual activity are some of the more common triggers. Certain natural disasters such as earthquakes and blizzards have also been associated with an increase in cardiac events. Certain unnatural triggers may play a role including the Holiday season. Holiday season cardiac events peak on Christmas and New Year. A number of hypotheses have been raised to explain the increase in cardiac events during the holidays, including overeating, excessive use of salt and alcohol, exposure to particulates, from fireplaces, a delay in seeking medical help, anxiety or depression related to the holidays, and poorer staffing of health care facilities at this time. War has been associated with an increase in cardiac events. Data regarding an increase in cardiac events during the 9/11 terrorist attack have been mixed. Understanding the cause of cardiovascular triggers will help in developing potential therapies.

New Opportunities for Identification and Reduction of Coronary Risk

Advances in the understanding of the role of vulnerable plaque in the causation of coronary events, coupled with novel diagnostic and therapeutic approaches, create a new opportunity for progress against cardiovascular disease. The recognition that non-flow-limiting plaques often produce cardiac events has led to the development of invasive and non-invasive methods to identify such plaques prospectively. Treatments such as stenting, photodynamic therapy, and novel pharmaceutical agents are under consideration as methods to stabilize the vulnerable plaques and patients that might be detected, thereby enhancing both primary and secondary prevention. Despite the promise of the field, many issues remain to be resolved, including the focality versus systemic nature of the atherosclerotic process, the ability of detectors to identify the target for which they were developed and prove that such a target is linked to clinical events, and the efficacy of specific therapy. If vulnerable plaques and patients can be successfully identified and treated, there will be immense clinical benefits, accompanied by cost savings.

Oxidative stress by peripheral blood mononuclear cells is increased in hypertensives with an extreme-dipper pattern and/or morning surge in blood pressure

Because oxidative stress and inflammation are known to play important roles in the pathogenesis of cardiovascular events that occur most frequently in the morning, we studied the association between reactive oxygen species (ROS) formation by polymorphonuclear leukocytes (PMNs) or mononuclear cells (MNCs) and morning blood pressure (BP) rhythm. A total of 31 hypertensives in whom ambulatory BP monitoring was performed participated in this study. They were first divided into three groups according to their nocturnal BP rhythm (non-dippers, dippers and extreme dippers), and then into two groups according to their morning BP change (surge-type and sustained-type). ROS formation by PMNs and MNCs was measured by gated flow cytometry. C-reactive protein and traditional risk factors such as age, gender, body mass index, hemoglobin A1c, and total cholesterol were also measured. ROS formation by MNCs was significantly increased in extreme dippers (vs. dippers, p<0.05, n=11) and in morning BP surge-type hypertensives (vs. sustained-type, p<0.05, n=13). In patients who were both extreme dippers and morning BP surge-types, ROS formation by MNCs was significantly higher than that in other groups. These results suggest that both extreme dippers and morning BP surge-type hypertensives may suffer increased ROS formation by MNCs, and that increased ROS formation by MNCs may underlie morning strokes.

Clinical imaging of the vulnerable plaque in the coronary arteries: new intracoronary diagnostic methods

Rupture of a vulnerable plaque is the main cause of acute coronary syndromes and myocardial infarction. The features of rupture-prone atherosclerotic plaques have been previously described by pathologists. However, identification of vulnerable plaques in vivo is essential to study their natural history and to evaluate potential treatment modalities. Coronary angiography is the gold standard for the diagnosis of coronary artery disease, but it is unable to distinguish between stable and unstable plaques and to accurately predict future cardiac events. This current perspective describes the recently developed invasive imaging techniques to detect atherosclerotic vulnerable plaques in the coronary tree.

Morning Hypertension: The Strongest Independent Risk Factor for Stroke in Elderly Hypertensive Patients

Stroke occurs most frequently in the morning hours, but the impact of the morning blood pressure (BP) level on stroke risk has not been fully investigated in hypertensives. We studied stroke prognosis in 519 older hypertensives in whom ambulatory BP monitoring was performed, and who were followed prospectively. During an average duration of 41 months (range: 1-68 months), 44 stroke events occurred. The morning systolic BP (SBP) was the strongest independent predictor for stroke events among clinic, 24-h, awake, sleep, evening, and pre-awake BPs, with a 10 mmHg increase in morning SBP corresponding to a relative risk (RR) of 1.44 (p<0.0001). The average of the morning and evening SBP (Av-ME-SBP; 10 mmHg increase: RR=1.41, p=0.0001), and the difference between the morning and evening SBP (Di-ME-SBP; 10 mmHg increase: RR=1.24, p=0.0025) were associated with stroke risks independently of each other. The RR of morning hypertension (Av-ME-SBP > or = 135 mmHg and Di-ME-SBP > or = 20 mmHg) vs. sustained hypertension (Av-ME-SBP > = 135 mmHg and Di-ME-SBP < or = 20 mmHg) for stoke events was 3.1 after controlling for other risk factors (p=0.01). In conclusion, morning hypertension is the strongest independent predictor for future clinical stroke events in elderly hypertensive patients, and morning and evening BPs should be monitored in the home as a first step in the treatment of hypertensive patients.

Socio economic crisis and mortality. Epidemiological testimony of the financial collapse of Argentina

Background

Natural disasters, war, and terrorist attacks, have been linked to cardiac mortality. We sought to investigate whether a major financial crisis may impact on the medical management and outcomes of acute coronary syndromes.

Methods

We analyzed the Argentine cohort of the international multicenter Global Registry of Acute Coronary Events (GRACE). The primary objective was to estimate if there was an association between the financial crisis period (April 1999 to December 2002) and in- hospital cardiovascular mortality, with the post-crisis period (January 2003 to September 2004) as the referent. Each period was defined according to the evolution of the Gross Domestic Product. We investigated the demographic characteristics, diagnostic and therapeutic procedures, morbidity and mortality.

Results

We analyzed data from 3220 patients, 2246 (69.8%) patients in the crisis period and 974 (30.2%) in the post-crisis frame. The distribution of demographic and clinical baseline characteristics were not significantly different between both periods. During the crisis period the incidence of in-hospital myocardial infarction was higher (6.9% Vs 2.9%; p value < 0.0001), as well as congestive heart failure (16% Vs 11%; p value < 0.0001). Time to intervention with angioplasty was longer during the crisis, especially among public sites (median 190 min Vs 27 min). The incidence proportion of mortality during hospitalization was 6.2% Vs 5.1% after crisis. The crude OR for mortality was 1.2 (95% C.I. 0.87, 1.7). The odds for mortality were higher among private institutions {1.9 (95% C.I. 0.9, 3.8)} than for public centers {1.2 (95% C.I. 0.83, 1.79)}. We did not observe a significant interaction between type of hospital and crisis.

Conclusion

Our findings suggest that the financial crisis may have had a negative impact on cardiovascular mortality during hospitalization, and higher incidence of medical complications.

Excess cardiac mortality on Monday: the importance of gender, age and hospitalisation

BACKGROUND

Available evidence suggests a peak in the incidence of cardiovascular events on Mondays compared to other days of the week. The underlying mechanism may be summarised as naturally occurring rhythmic fluctuations in human physiology, and socially determined rhythms in human behaviour. Change in these rhythms may lead to attenuation of the peak on Mondays.

OBJECTIVE

To quantify the excess risk associated with the Monday peak in cardiovascular mortality and to explore the role of age, gender and hospitalisation.

METHODS

Details on time and cause of all deaths which occurred in the city of Rotterdam between November 21, 1988 and November 21, 1990 were obtained by sending a questionnaire to the physician who signed the death certificate. We studied the weekly distribution of 1828 confirmed cases of sudden cardiac death, for the group as a whole and in subgroups according to gender, age (< 65 years/65 years) and hospitalisation.

RESULTS

The odds ratio (OR) of sudden cardiac death on Monday compared to other days of the week was 1.20 (95% CI: 1.06-1.36). The excess mortality due to the Monday peak amounted to 4.9 per 1000 deaths. The Monday peak was more pronounced in non-hospitalised (OR: 1.25; 95% CI: 1.08-1.44) than in hospitalised patients (OR: 1.06; 95% CI: 0.83-1.37), in men (OR: 1.25; 95% CI: 1.06-1.48) than in women (OR: 1.14; 95% CI: 0.95-1.36), and in those younger than 65 (OR: 1.29; 95% CI: 0.95-1.74) compared to those aged 65 years or over (OR: 1.18; 95% CI: 1.03-1.35). Yet, the confidence limits overlap.

CONCLUSION

The incidence of sudden cardiac death is markedly increased on Monday, more pronounced in non-hospitalised patients. Our results may point to the relevance of naturally occurring rhythmic fluctuations in human physiology, and socially determined rhythms in human behaviour as underlying mechanism.

Biomechanical interaction between cap thickness, lipid core composition and blood pressure in vulnerable coronary plaque: impact on stability or instability

BACKGROUND

A 'thin' fibrous cap atheroma is the typical morphological characteristic of vulnerable plaque. Yet the very pathological studies that have provided these descriptions have also shown the actual prediction of plaque rupture to be rather less exact. Other relevant characteristics must be involved in the mechanisms of plaque rupture--blood pressure loading (P) and the material properties of the soft atheromatous core--as predictors of the distribution of the peak circumferential stress (PCS) locations.

METHODS AND RESULTS

We used a computational structural analysis based on three typical in-vivo intravascular ultrasound images of fibrous cap atheroma in which we decreased the cap thickness (CTh). With different soft atheromatous core Young's moduli (Ecore), 414 simulations were performed under eight different physiological loading blood pressures. The transition from plaque stability to plaque instability was defined by a threshold of 300 kPa and is a feature of vulnerability. It was found that (1) irrespective of plaque geometry and composition, CTh < 60 microm exposed the plaque to PCSs in excess of 300 kPa; (2) the exponential variations in PCS with change in CTh and Ecore values show that very slight structural changes are enough to tilt a vulnerable plaque from stability to instability or vice versa; and (3) the relationship between P and PCS is proportional with P acting as trigger or as protector.

CONCLUSION

The present study shows why, in clinical practice, mere morphological detection by imaging techniques of thin-cap fibro-atheroma is not in itself enough for the prediction of future rupture.

Work related stressful life events and the risk of myocardial infarction. Case-control and case-crossover analyses within the Stockholm heart epidemiology programme (SHEEP)

STUDY OBJECTIVES

Recent changes in labour market conditions and in the organisation of work in developed societies have increased exposure to work related stress. The question is whether this also implies an increased risk of myocardial infarction, either through the triggering effect of acute stress, or through accumulation of stress over several months.

DESIGN

A case-control and a case-crossover study design was applied.

SETTING

The Stockholm heart epidemiology programme (SHEEP), in Stockholm County during 1992 to 1994.

PARTICIPANTS

Patients with a first episode of non-fatal acute myocardial infarction, a total of 1381 men and women, responded to questionnaires and participated in interviews and health examinations.

MAIN RESULTS

The case-crossover analysis showed triggering effects of sudden, short term situations of increased work load or work competition. Having "had a high pressure deadline at work" entailed a sixfold increase in risk of myocardial infarction (OR = 6.0 95% CI (1.8 to 20.4)) during the next 24 hours. The importance of work related life events as risk factors for myocardial infarction was supported by the case-control analysis. However, no support was found for the hypothesis that an accumulation of stressful life events over a period of 12 months increases the risk of myocardial infarction.

CONCLUSION

Specific work related stressful life events seem to be potential triggers of the onset of myocardial infarction.