Circadian variation of plasma fibrinopeptide A level in patients with variant angina

Layered Plaque in Organic Lesions in Patients With Coronary Artery Spasm

Background

Coronary artery spasm plays a vital role in the pathogenesis of coronary plaques. We sought to investigate the plaque characteristics of co‐existing organic lesions in patients with coronary artery spasm in comparison to those without coronary artery spasm by intracoronary optical coherence tomography (OCT).

Methods and Results

We included 39 patients who presented with a symptom suspected of coronary spastic angina and had an organic lesion, defined as ≥plaque burden of 50% assessed by OCT. Coronary artery spasm was diagnosed by positive acetylcholine provocation test, or by spontaneous spasm detected during coronary angiography. A total of 51 vessels with an organic lesion were identified. Of these, coronary artery spasm was observed in 30 vessels (spasm), while not in 21 vessels (non‐spasm). Organic lesions in the spasm vessels, compared with those in the non‐spasm vessels, had a higher prevalence of layered plaque (93% versus 38%, P<0.001), macrophages (80% versus 43%, P=0.016), and intraplaque microchannels (73% versus 24%, P<0.001), and lower prevalence of macrocalcification (23% versus 62%, P=0.009) as assessed by OCT.

Conclusions

Layered plaque, macrophages, and intraplaque microchannels, were frequently observed in organic lesions in patients with coronary artery spasm. These findings suggest that coronary artery spasm induces local thrombus formation as well as active inflammatory response, therefore increasing the risk of rapid plaque progression and ischemic events in patients with coronary artery spasm.

Pathobiology and evolving therapies of coronary artery vasospasm

Coronary artery vasospasm is a known cause of chest pain and requires a high level of clinical suspicion for diagnosis. It also remains in the differential diagnosis for patients presenting with type 2 myocardial infarction. There are few randomized controlled trials for guideline-based prevention and treatment for coronary artery vasospasm. In this article, we review updated concepts in coronary artery vasospasm. Specifically, our aim is to provide current evidence of pathophysiology, identify the risk factors, propose a diagnostic algorithm, review available evidence of evolving therapies, and identify patients who would benefit from automatic implantable cardioverter defibrillators.

Role of acetylcholine spasm provocation test as a pathophysiological assessment in nonobstructive coronary artery disease

Coronary angiography (CAG) sometimes shows nonobstructive coronary arteries in patients with suspected angina or acute coronary syndrome (ACS). The high prevalence of nonobstructive coronary artery disease (CAD) in those patients has recently been reported not only in Japan but also in Western countries, and is clinically attracting attention. Coronary spasm is considered to be one of the leading causes of both suspected stable angina and ACS with nonobstructive coronary arteries. Coronary spasm could also be associated with left ventricular dysfunction leading to heart failure, which could be improved following the administration of calcium channel blockers. Because we rarely capture spontaneous attacks of coronary spasm with electrocardiograms or Holter recordings, an invasive diagnostic modality, acetylcholine (ACh) provocation test, can be useful in detecting coronary spasm during CAG. Furthermore, we can use the ACh-provocation test to identify high-risk patients with coronary spasm complicated with organic coronary stenosis, and then treat with intensive care. Nonobstructive CAD includes not only epicardial coronary spasm but also microvascular spasm or dysfunction that can be associated with recurrent anginal attacks and poor quality of life. ACh-provocation test could also be helpful for the assessment of microvascular spasm or dysfunction. We hope that cardiologists will increasingly perform ACh-provocation test to assess the pathophysiology of nonobstructive CAD.

Coronary Artery Spasm: New Insights

Coronary artery spasm (CAS) defined by a severe reversible diffuse or focal vasoconstriction is the most common diagnosis among INOCA (ischemia with no obstructive coronary artery disease) patients irrespective to racial, genetic, and geographic variations. However, the prevalence of CAS tends to decrease in correlation with the increasing use of medicines such as calcium channel blockers, angiotensin converting enzyme inhibitor, and statins, the controlling management of atherosclerotic risk factors, and the decreased habitude to perform a functional reactivity test in highly active cardiac catheterization centers. A wide spectrum of clinical manifestations from silent disease to sudden cardiac death was attributed to this complex entity with unclear pathophysiology. Multiple mechanisms such as the autonomic nervous system, endothelial dysfunction, chronic inflammation, oxidative stress, and smooth muscle hypercontractility are involved. Regardless of the limited benefits proffered by the newly emerged cardiac imaging modalities, the provocative test remains the cornerstone diagnostic tool for CAS. It allows to reproduce CAS and to evaluate reactivity to nitrates. Different invasive and noninvasive therapeutic approaches are approved for the management of CAS. Long-acting nondihydropyridine calcium channel blockers are recommended for first line therapy. Invasive strategies such as PCI (percutaneous coronary intervention) and CABG (coronary artery bypass graft) have shown benefits in CAS with significant atherosclerotic lesions. Combination therapies are proposed for refractory cases.

Acute Myocardial Infarction in Young Individuals

Globally, cardiovascular disease remains a major cause of adverse outcomes in young individuals, unlike its decline in other age groups. This group is not well studied and has a unique risk profile with less traditional cardiovascular risk factors compared with older populations. Plaque rupture still remains the most common etiology of myocardial infarction, but unique syndromes such as plaque erosion, coronary microvascular dysfunction, spontaneous coronary artery dissection, and coronary spasm related to drug use are more prevalent in this age group. Such diversity of diagnosis and presentation, along with therapeutic implications, underscore the need to study the profile of myocardial infarction in young persons. We searched PubMed for articles published from 1980 to 218 using the terms acute myocardial infarction, young, plaque rupture, plaque erosion, spontaneous coronary artery dissection (SCAD), coronary vasospasm, variant or Prinzmetal angina, drug-induced myocardial infarction, myocarditis, coronary embolism, microvascular dysfunction, MINOCA, and myocardial infarction in pregnancy and reviewed all the published studies. With the data from this search, we aim to inform readers of the prevalence, risk factors, presentation, and management of acute myocardial infarction in young patients and elaborate on special subgroups with diagnostic and therapeutic challenges. We also outline a parsimonious method designed to simplify management of these complex patients.

Coronary Artery Spasm as Related to Anxiety and Depression: A Nationwide Population-Based Study

OBJECTIVE

Anxiety and depression are risk factors for obstructive coronary artery disease (CAD), but their effects on coronary artery spasm (CAS) remain unestablished.

METHODS

Patient records in this population-based study were retrospectively collected from the Taiwan National Health Insurance Research Database. Using propensity score matching, we used 1:1:1 ratio stratification into a control group of 10,325 individuals without CAS or CAD, a CAS group comprising 10,473 patients, and a CAD group comprising 10,473 patients during 2000-2012.

RESULTS

The prevalence of CAS and CAD was 0.067% and 8.7%, respectively, in the general population. The prevalence of anxiety and depression diagnoses was significantly higher in patients with new-onset CAS than in those with new-onset CAD and controls without CAS/CAD, even after propensity score matching. Compared with CAD, anxiety and depression diagnoses conferred a higher risk of developing CAS (odds ratio [OR] = 2.29, 95% confidence interval [CI], 2.14-2.45, p < .001, and OR = 1.34, 95% CI, 1.08-1.66, p = .007, respectively). The association was even stronger when comparing CAS with the control group without CAD or CAS (OR = 5.20, 95% CI, 4.72-5.74, p < .001, and OR = 1.98, 95% CI, 1.50-2.62, p < .001, respectively). The increased risk of new-onset CAS as related to previous anxiety and depression diagnoses was comparable between males and females.

CONCLUSIONS

Compared with CAD or the general population, anxiety and depression diagnoses confer a higher risk of developing CAS. No sex differences are found for the association of anxiety and depression with CAS.

Coronary artery spasm - Clinical features, pathogenesis and treatment

Coronary artery spasm (CAS) plays an important role in the pathogenesis of ischemic heart disease, including angina pectoris, myocardial infarction, and sudden death, occurring most often from midnight to early morning. CAS is prevalent among East Asians and is associated with an aldehyde dehydrogenase 2 (ALDH2)-deficient genotype (ALDH2*2) and alcohol flushing, which is prevalent among East Asians but is virtually non-existent in other populations. ALDH2 eliminates not only acetaldehyde but also other toxic aldehydes from lipid peroxidation and tobacco smoking, thereby protecting tissues and cells from oxidative damage. Risk factors for CAS include smoking and genetic polymorphisms including those of ALDH2*2, endothelial NO synthase, paraoxonase I, and interleukin-6. Accordingly, oxidative stress, endothelial dysfunction, and low-grade chronic inflammation play an important role in the pathogenesis of CAS, leading to increased coronary smooth muscle Ca²⁺ sensitivity through RhoA/ROCK activation and resultant hypercontraction. Ca-channel blockers blocking the intracellular entry of Ca²⁺ are specifically effective for treatment for CAS.

Clinical and morphological presentations of acute coronary syndrome without coronary plaque rupture - An intravascular ultrasound study

BACKGROUND

Although acute coronary syndrome (ACS) mainly arises from plaque ruptures (PR), precise mechanisms underlying ACS without PR are unknown. We sought to examine clinical, angiographic and intravascular ultrasound (IVUS) characteristics of ACS without PR.

METHODS AND RESULTS

Culprit lesions of 161 ACS patients were categorized by the presence or absence of PR (PR group: n=57, Non-PR group: n=104). Lower abdominal circumference (86±10cm vs 90±9cm, p=0.02), lower prevalence of myocardial infarction (53% vs 82%, p=0.0002), and higher prevalence of definite vasospasm (15% vs 2%, p=0.006) were found in Non-PR group. Morphologically, Non-PR group was associated with simpler Ambrose classification (36% vs 14%, p=0.004), less hypoechoic plaque (45% vs 65%, p=0.04) and lower incidence of IVUS-detected thrombus (21% vs 54%, p<0.0001), compared with PR group. On quantitative IVUS, although minimum lumen area (MLA) was similar between the groups, vessel (14.2±5.4mm(2) vs 17.5±5.1mm(2), p=0.0002) and plaque (11.6±5.0mm(2) vs 14.9±4.9mm(2), p<0.0001) areas were significantly smaller at MLA site in Non-PR group than in PR group. On multivariate analysis, average plaque area was only an independent IVUS-predictor of non-rupture ACS (odds ratio: 0.85, p=0.01).

CONCLUSION

Compared to ACS with PR, non-rupture ACS arise from more hyperechoic (allegedly "stable") plaque with smaller vessel and plaque area, leading to lower incidence of thrombotic occlusion. Coronary vasospasm might be a possible pathogenic mechanism underlying non-rupture ACS.

State-of-the-Art Review: Usefulness of Laboratory Techniques for Evaluating Antithrombotic Efficacy of New Therapeutic Strategies

New drugs and new therapeutic strategies are being introduced for the prevention and the management of cardiovascular and thromboembolic disorders. Extensive clinical studies and large-scale epidemiological investigations are conducted to demonstrate the efficacy of these therapeutic approaches. Laboratory assays are invaluable tools for this exploration. We discuss how the new understanding concerning the regulation of the coagulolytic equilibrium offers novel investigation tools. Parameters reflecting the activities of new drugs targeted to their impact site and presenting few side effects are available. In addition to global clotting methods and chromogenic substrate-based assays, introduction of immunoassays has allowed measurement of most of the molecular markers of hemostatic activation. We recommend use of a panel of markers exploring the endothelial damage, the blood cell involvement, the early coagulant pathways' activation (XIIa and VIIa), the thrombin-formation pathways, the fibrin formation, and the evaluation of the global fibrinolytic capacity. When related to the clinical end points, all these laboratory assays offer useful and reliable monitoring of new drugs. They contribute to the establishment of new therapeutic strategies. Key Words: Hemostasis—Activation—Antithrombotic—Therapy— Laboratory monitoring.

Determinants of Myocardial Lactate Production During Acetylcholine Provocation Test in Patients With Coronary Spasm

BACKGROUND

Myocardial lactate production in the coronary circulation during acetylcholine (ACh)-provocation test (abbreviated as lactate production) provides supporting evidence for coronary spasm-induced myocardial ischemia. The purpose of this study was to examine the clinical features, predictive factors, and prognosis of patients with coronary vasospastic angina (VSA) and lactate production.

METHODS AND RESULTS

We examined all 712 patients who underwent both myocardial lactate measurement during ACh-provocation test in the left coronary artery and genetic screening test of a -786T/C polymorphism in the 5'-flanking region of the endothelial nitric oxide synthase (eNOS) gene between January 1991 and December 2010. Lactate production was observed in 252 of the 712 patients and in 219 of 356 VSA patients diagnosed by ACh-provocation test. Compared with lactate production-negative VSA patients, the lactate production-positive counterparts were more likely to be nonsmoker female diabetics with -786T/C eNOS polymorphism (61% vs 31%, P<0.001, 62% vs 34%, P<0.001, 24% vs 14%, P=0.016, and 25% vs 15%, P=0.018, respectively). Multivariable logistic regression analysis identified female sex, diabetes mellitus, and -786T/C eNOS polymorphism to correlate with lactate production (odds ratio 3.51, 95% CI 2.16 to 5.70, P<0.001; odds ratio 2.53, 95% CI 1.38 to 4.65, P=0.003; and odds ratio 1.85, 95% CI 1.02 to 3.35, P=0.044, respectively). Kaplan-Meier survival curve showed no difference in 5-year survival rate free from major adverse cardiac events between lactate production-positive and -negative VSA patients (P=0.319).

CONCLUSIONS

The results indicated that female sex, diabetes, and mutation in -786T/C eNOS gene correlate with ACh-provoked myocardial ischemia in patients with coronary spasm.

Identification of protein biomarkers associated with cardiac ischemia by a proteomic approach

Angina is chest pain induced by ischemia of the heart muscle, generally due to obstruction or spasm of the coronary arteries. People that suffer from average to severe cases of angina have an increased percentage of death before the age of 55, usually around 60%. Therefore, prevention of major complications, optimizing diagnosis, prognosis and therapeutics are of primary importance. The main objective of this study was to uncover biomarkers by comparing serum protein profiles of patients suffering from stable or unstable angina and controls. We identified by non-targeted proteomic approach and confirmed by the means of independent techniques, the differential expression of several proteins indicating significantly increased vascular inflammation response, disturbance in the lipid metabolism and in atherogenic plaques stability.

Intermittent left bundle branch block caused by coronary vasospasm

Intermittent left bundle branch block (LBBB) has been reported in the literature following certain conditions such as cardiac blunt trauma, myocardial infarction (MI) or exercise induced LBBB. In the majority of cases, the patients usually have underlying coronary arteries disease. LBBB often prevents the electrocardiographic diagnosis of acute MI; therefore, new LBBB in the setting of chest pain is usually treated as transmural MI. We describe a case of patient who presented with intermittent LBBB associated with chest pain, and subsequently the patient was taken to the catheterization laboratory for emergency coronary angiogram, which revealed 80% spasm in left anterior descending artery, which was totally relieved by nitroglycerin infusion. No other significant CAD was noted.

Coronary vasomotor response to intracoronary acetylcholine injection, clinical features, and long-term prognosis in 873 consecutive patients with coronary spasm: analysis of a single-center study over 20 years

BACKGROUND

The aim of this study was to elucidate the correlation between angiographic coronary vasomotor responses to intracoronary acetylcholine (ACh) injection, clinical features, and long-term prognosis in patients with vasospastic angina (VSA).

METHODS AND RESULTS

This is a retrospective, observational, single-center study of 1877 consecutive patients who underwent ACh-provocation test between January 1991 and December 2010. ACh-provoked coronary spasm was observed in 873 of 1637 patients included in the present analysis. ACh-positive patients were more likely to be older male smokers with dyslipidemia, to have a family history of ischemic heart disease, and to have a comorbidity of coronary epicardial stenosis than were ACh-negative patients. ACh-positive patients were divided into 2 groups: those with focal (total or subtotal obstruction, n=511) and those with diffuse (severe diffuse vasoconstriction, n=362) spasm patterns. Multivariable logistic regression analysis identified female sex and low comorbidity of coronary epicardial stenosis to correlate with the ACh-provoked diffuse spasm pattern in patients with VSA. Kaplan-Meier survival curve indicated better 5-year survival rates free from major adverse cardiovascular events in patients with diffuse spasm pattern compared with those with focal spasm pattern (P=0.019). Multivariable Cox hazard regression analysis identified diffuse spasm pattern as a negative predictor of major adverse cardiovascular events in patients with VSA.

CONCLUSIONS

ACh-induced diffuse coronary spasm was frequently observed in female VSA patients free of severe coronary epicardial stenosis and was associated with better prognosis than focal spasm. These results suggest the need to identify the ACh-provoked coronary spasm subtypes in patients with VSA.

Twenty-four-hour patterns in occurrence and pathophysiology of acute cardiovascular events and ischemic heart disease

The scientific literature clearly establishes the occurrence of cardiovascular (CV) accidents and myocardial ischemic episodes is unevenly distributed during the 24 h. Such temporal patterns result from corresponding temporal variation in pathophysiologic mechanisms and cyclic environmental triggers that elicit the onset of clinical events. Moreover, both the pharmacokinetics and pharmacodynamics of many, though not all, CV medications have been shown to be influenced by the circadian time of their administration, even though further studies are necessary to better clarify the mechanisms of such influence on different drug classes, drug molecules, and pharmaceutical preparations. Twenty-four-hour rhythmic organization of CV functions is such that defense mechanisms against acute events are incapable of providing the same degree of protection during the day and night. Instead, temporal gates of excessive susceptibility exist, particularly in the morning and to a lesser extent evening (in diurnally active persons), to aggressive mechanisms through which overt clinical manifestations may be triggered. When peak levels of critical physiologic variables, such as blood pressure (BP), heart rate (HR), rate pressure product (systolic BP × HR, surrogate measure of myocardial oxygen demand), sympathetic activation, and plasma levels of endogenous vasoconstricting substances, are aligned together at the same circadian time, the risk of acute events becomes significantly elevated such that even relatively minor and usually harmless physical and mental stress and environmental phenomena can precipitate dramatic life-threatening clinical manifestations. Hence, the delivery of CV medications needs to be synchronized in time, i.e., circadian time, in proportion to need as determined by established temporal patterns in risk of CV events, and in a manner that averts or minimizes undesired side effects.

Sudden cardiac arrest and syncope triggered by coronary spasm

BACKGROUND

Patients with coronary spasm generally have a good prognosis, although it can result in sudden cardiac arrest (SCA) and syncope. We hypothesized that the nature of coronary spasm triggering lethal arrhythmias may be different from that which induces angina-only.

METHODS

Clinical characteristics were examined in patients who had experienced SCA (n = 18) or syncope (n = 28) triggered by coronary spasm. These characteristics were compared to those of patients who had coronary spastic angina-only (n = 52).

RESULTS

SCA and syncope occurred frequently during daytime in 57% and 68%, respectively. Spontaneous ST-segment changes during daytime were recorded more often in patients with SCA (50%) and syncope (39%) than angina-only patients (4%, p < 0.01 for each). Nocturnal angina occurred less frequently in patients with SCA (33%) and syncope (32%) than angina-only patients (83%, p < 0.01 for each). Severe multivessel spasm, daytime ST-segment changes, and younger age were significant predictors of SCA. Daytime ST-segment changes and active smoking were related to syncope.

CONCLUSIONS

The circadian variance of coronary spasm triggering SCA or syncope may be different from that inducing typical coronary spastic angina. The coronary spasm should be evaluated for patients with aborted SCA or recurrent syncope of unknown cause, even though the patients have not experienced the typical nocturnal angina.

Circadian rhythms and cardiovascular health

The functional organization of the cardiovascular system shows clear circadian rhythmicity. These and other circadian rhythms at all levels of organization are orchestrated by a central biological clock, the suprachiasmatic nuclei of the hypothalamus. Preservation of the normal circadian time structure from the level of the cardiomyocyte to the organ system appears to be essential for cardiovascular health and cardiovascular disease prevention. Myocardial ischemia, acute myocardial infarct, and sudden cardiac death are much greater in incidence than expected in the morning. Moreover, supraventricular and ventricular cardiac arrhythmias of various types show specific day-night patterns, with atrial arrhythmias--premature beats, tachycardias, atrial fibrillation, and flutter - generally being of higher frequency during the day than night--and ventricular fibrillation and ventricular premature beats more common, respectively, in the morning and during the daytime activity than sleep span. Furthermore, different circadian patterns of blood pressure are found in arterial hypertension, in relation to different cardiovascular morbidity and mortality risk. Such temporal patterns result from circadian periodicity in pathophysiological mechanisms that give rise to predictable-in-time differences in susceptibility-resistance to cyclic environmental stressors that trigger these clinical events. Circadian rhythms also may affect the pharmacokinetics and pharmacodynamics of cardiovascular and other medications. Knowledge of 24-h patterns in the risk of cardiac arrhythmias and cardiovascular disease morbidity and mortality plus circadian rhythm-dependencies of underlying pathophysiologic mechanisms suggests the requirement for preventive and therapeutic interventions is not the same throughout the day and night, and should be tailored accordingly to improve outcomes.

Effects of treatment with once-daily nifedipine CR and twice-daily benidipine on prevention of symptomatic attacks in patients with coronary spastic angina pectoris-Adalat Trial vs Coniel in Tokyo against Coronary Spastic Angina (ATTACK CSA)

BACKGROUND

We compared the efficacy of once-daily treatment with nifedipine CR 40 mg (NR) and twice-daily treatment with benidipine 4 mg (BD) in patients with coronary spastic angina (CSA) registered in 3 cardiovascular institutes in Tokyo.

METHODS AND RESULTS

CSA was diagnosed by an ischemic ST change during Holter ECG monitoring or drug-induced test. Thirty patients were randomly allocated to either NR or BD group. The number of symptomatic attacks and the total frequency of short-acting nitrates were examined based on the data in diaries written by patients. There were no significant differences in the baseline characteristics between the two groups. The median number (25-75% quartile) of attacks per week was significantly decreased in NR group, i.e., 1.0 (0.8-2.0) at baseline, 0.0 (0.0-1.0) after 4 weeks of treatment, and 0.0 (0.0-0.0) after 8 weeks of treatment (P=0.0093, P=0.0002, Wilcoxon's rank-sum test). No significant decrease was observed in BD, i.e. 1.0 (0.5-2.0) at baseline, 1.3 (0.0-3.0) after 4 weeks, and 0.0 (0.0-1.0) after 8 weeks. The number of attacks was fewer in NR than in BD group (P=0.074, P=0.015, U-test for difference).

CONCLUSION

Once-daily treatment with NR 40 mg was more effective than twice-daily treatment with BD in the prevention of CSA attacks.

Influence of the Circadian System on Disease Severity

The severity of many diseases varies across the day and night. For example, adverse cardiovascular incidents peak in the morning, asthma is often worse at night and temporal lobe epileptic seizures are most prevalent in the afternoon. These patterns may be due to the day/night rhythm in environment and behavior, and/or endogenous circadian rhythms in physiology. Furthermore, chronic misalignment between the endogenous circadian timing system and the behavioral cycles could be a cause of increased risk of diabetes, obesity, cardiovascular disease and certain cancers in shift workers. Here we describe the magnitude, relevance and potential biological basis of such daily changes in disease severity and of circadian/behavioral misalignment, and present how these insights may help in the development of appropriate chronotherapy.

Multifocal spasm with acetylcholine in Prinzmetal angina

A 60-year-old female patient with Prinzmetal angina and a single non-critical (<50%) focal obstruction in the right coronary artery was referred for percutaneous coronary intervention. Coronary angiography with provocative testing using incremental doses of acetylcholine demonstrated diffuse mild vasoconstriction and multifocal hyperreactive vasoconstriction in apparently normal coronary segments but not at the site of the nonsignificant obstruction. We refrained from intervention and advised avoidance of beta-blockade, and continuation of medical therapy with nitrates and calcium antagonists. (Neth Heart J 2008;16:134-6.).

[Up-date of the diagnosis and treatment of vasospastic angina]

Vasospastic or Prinzmetal's variant angina as it is also known is a special type of ischemic heart disease characterized by spontaneous episodes of chest pain accompanied by transitory ST segment elevations during the episodes. These alterations are essential for its diagnosis and it is difficult to diagnose it in their absence. If clinical suspicion is high, it should be confirmed by coronary vasospasm provocation tests, since, on the contrary, there may be cases that are not diagnosed or considered to be other types of diseases. Furthermore, progression of this type of angina to a myocardial infarction due to coronary stenosis is a relatively uncommon event.

Coronary artery spasm--clinical features, diagnosis, pathogenesis, and treatment

Coronary (artery) spasm plays an important role in the pathogenesis of ischemic heart disease, including stable angina, unstable angina, myocardial infarction, and sudden death. The prevalence of coronary spasm differs among populations, is higher in Japan and Korea than in the Western countries probably due to genetic as well as environmental factors. Coronary spasm occurs most often from midnight to early morning and is usually not induced by exercise in the daytime. The attacks of coronary spasm are associated with either ST segment elevation or depression, or negative U wave on ECG. Patients with multi-vessel coronary spasm may suffer from lethal arrhythmia, including advanced AV block, ventricular tachycardia or fibrillation, or even sudden death, and they are often resistant to conventional medical therapy including Ca-channel blockers (CCBs). Endothelial nitric oxide (NO) activity is reduced and markers of oxidative stress are elevated in patients with coronary spasm. Thrombogenesis is enhanced and plasma levels of hsCRP and P-selection are elevated in patients with coronary spasm. Thus, patients with coronary spasm have endothelial dysfunction and are suffering from a low-grade chronic inflammation. Polymorphisms of endothelial NO synthase, smoking, and low-grade inflammation are the most important risk factors for coronary spasm. Coronary spasm is a hyper-contraction of coronary smooth muscle triggered by an increase of intracellular Ca2+ in the presence of an increased Ca2+ sensitivity. It has been shown that RhoA/ROCK pathway is involved in Ca2+ sensitivity and that the reduced endothelial NO activity results in increased Ca2+ sensitivity through enhanced RhoA/ROCK pathway. Accordingly, it is possible that in addition to CCBs, RhoA/ROCK pathway blockers may prove to be useful for the treatment of coronary spasm.

Chronobiology of hemostasis and inferences for the chronotherapy of coagulation disorders and thrombosis prevention

The hemostatic system in its multiple components displays an intricate organization in time which is characterized by circadian (approximately 24-hour), circaseptan (approximately 7-day), menstrual (approximately monthly), and circannual (approximately yearly) bioperiodicities. The interaction of the rhythms of the variables participating in hemostasis determine transient risk states of thromboembolic events, including myocardial infarction and stroke, and of hemorrhage and hemorrhagic events, each with a unique timing. The circadian staging of the rhythms in vascular, cellular, and coagulation factors that favors blood coagulation and thrombosis coincides with the daily minimum in fibrinolytic activity; as a result there is elevated risk in the morning of acute myocardial infarction and stroke. Similar hemostatic rhythms may determine the epidemiology of thromboembolic and hemorrhagic events during the week, month and year. This article focuses on the large-amplitude circadian rhythms operative in the hemostatic system. Their implication for preventive and curative pharmacotherapy of hemostatic disorders is presented, with discussion of related problems.

Chronobiology and chronotherapy of ischemic heart disease

The occurrence of the clinical manifestations of ischemic heart disease (IHD)--myocardial ischemia and angina pectoris, acute myocardial infarction, and sudden cardiac death--is unevenly distributed during the 24 h with greater than expected events during the initial hours of the daily activity span and in the late afternoon or early evening. Such temporal patterns result from circadian rhythms in pathophysiological mechanisms plus cyclic environmental stressors that trigger ischemic events. Both the pharmacokinetics (PK) and pharmacodynamics (PD) of many, though not all, anti-ischemic oral nitrate, calcium channel blocker, and beta-adrenoceptor antagonist medications have been shown to be influenced by the circadian time of their administration. The requirement for preventive and therapeutic interventions varies predictably during the 24 h, and thus therapeutic strategies should also be tailored accordingly to optimize outcomes. During the past decade, two first generation calcium channel blocker chronotherapies have been developed, trialed, and marketed in North America for the improved treatment of IHD. Nonetheless, there has been relatively little investigation of the administration-time (circadian rhythm) dependencies of the PK and PD of conventional anti-ischemic medications, and there has been little progress in the development of new generation IHD chronotherapies. Available epidemiologic, pharmacologic, and clinico-therapeutic evidence demonstrates how the chronobiologic approach to IHD can contribute new insight and opportunities to improve drug design and drug delivery to enhance therapeutic outcomes.

Importance of aggressive blood pressure lowering when it may matter most

Variation in blood pressure levels follows a reproducible circadian pattern, characterized by low levels during sleep and a rapid increase during the early-morning period. The incidence of cardiovascular events displays a similar circadian variation, with peak occurrence coinciding with the early-morning blood pressure surge. Numerous prospective studies have shown that blood pressure measured over a 24-hour period is superior to clinic blood pressure in predicting future cardiovascular events. Thus, the use of ambulatory blood pressure monitoring (ABPM) to identify patients at risk of cardiovascular events could improve the management of the patient with hypertension. ABPM has also become widely adopted to evaluate antihypertensive therapeutic options that might provide blood pressure reduction throughout the 24-hour dosing interval. Recently, community-based trials have shown that it is feasible to perform ABPM-oriented research in nonresearch environments. This allows us to better understand the efficacy of antihypertensive therapies in a "real-world" setting. Studies of this nature can even assess blood pressure control in the early-morning period by sequestering data before and after awakening.

The mystery of coronary artery spasm

Coronary artery spasm is an important cause of chest pain and myocardial ischaemia. It can be defined as an exaggerated contractile response of epicardial coronary artery smooth muscle to various stimuli but the underlying mechanism is not well understood. Recent studies have shown that the loss of endothelial vasodilatory function in conjunction with an increase in vascular smooth muscle constrictor sensitivity to calcium are the likely predisposing conditions for coronary spasm. This review highlights current understanding of the pathophysiology, predisposing factors, diagnostic and therapeutic approaches for coronary spasm.

Plaque instability in peripheral vessels

Vulnerable atherosclerotic plaques, those that are prone to rupture, are soft and lipid rich. Other factors that contribute to destabilizing these plaques are inflammation and vasoconstriction. Although less information is available regarding noncoronary vulnerable plaques than the more frequently studied coronary plaques, it appears that the amount of soft lipid "gruel" as well as in situ inflammation plays a crucial role in destabilizing peripheral vascular atherosclerotic plaque, eventually causing its rupture. As in the coronary circulation, it is likely that the majority of acute plaque rupture events are clinically silent. Nevertheless, preventing plaque rupture in the noncoronary circulation is of the utmost importance because this is the presumed mechanism of progression of peripheral vascular atherosclerotic lesions.