Triggering and the pathophysiology of acute coronary syndromes

Acute effects of high intensity interval training versus moderate intensity continuous training on haemostasis in patients with coronary artery disease

Exercise training is associated with an acute net increase in coagulation, which may increase the risk of atherothrombosis in coronary artery disease (CAD) patients. We sought to compare the acute haemostatic effects of a bout of moderate-intensity continuous (MICT) and high-intensity interval training (HIIT) in patients with CAD. Patients after a recent myocardial infarction were randomized into a HIIT or MICT session of exercise training on a stationary bike. Blood was sampled at baseline, after the exercise bout and after a one-hour resting period. We measured overall haemostatic potential (OHP), overall coagulation potential (OCP), fibrinogen, D-dimer and von Willebrand factor (vWF) and calculated overall fibrinolytic potential (OFP). Linear mixed models for repeated measures were constructed to assess the treatment effect. A total of 117 patients were included. OCP, OHP, fibrinogen, D-dimer and vWF significantly increased after exercise and returned to baseline after a one-hour rest, OFP decreased after exercise and returned to baseline levels after a one-hour rest. Linear mixed models showed a significant difference between HIIT and MICT in fibrinogen (p 0.043) and D-dimer (p 0.042). Our study has shown that an exercise bout is associated with a transient procoagulant state in patients with CAD, with similar exercise-induced haemostatic changes for HIIT and MICT.

Triggers of acute myocardial infarction: a neglected piece of the puzzle

The existence of specific risk factors for the development of coronary heart disease, both chronic and acute, has been extensively investigated and is well understood by cardiology professionals. Diabetes, hypertension, hypercholesterolemia, psychological patterns and smoking are assumed to interact in a complex way with individual heritable predisposition, thus determining the long-term probability of coronary disease. However, the possibility that defined circumstances and activities may act as immediate triggers of acute coronary syndromes, particularly acute myocardial infarction, has not been given comparable attention in clinical research. For example, the recently issued 2012 European guidelines on cardiovascular disease prevention completely overlook the topic of triggers and their possible prevention. This review presents a picture of the most reliable evidence regarding the triggering of myocardial infarction and contributes to further investigation in the field.

Disaster Events and the Risk of Sudden Cardiac Death: A Washington State Investigation

Background:

Psychological distress following disaster events may increase the risk of sudden cardiac death. In 2001, the Nisqually earthquake and the 11 September terrorist attacks profoundly affected Washington state residents.

Hypothesis:

This research investigated the theory that the incidence of sudden cardiac death would increase following these disaster events.

Methods:

Death certificates were abstracted using a uniform case definition to determine the number of sudden cardiac deaths for the 48-hour and one week periods following the two disaster events. Sudden cardiac deaths from the corresponding 48-hour and one-week periods in the three weeks before the events, and the analogous periods in 1999 and 2000 were designated as control times. Using t-tests, the number of sudden cardiac deaths for the periods following the disaster events was compared to those of the control periods.

Results:

In total, 32 sudden cardiac deaths occurred in the four counties affected by the Nisqually earthquake during the 48 hours after the event, compared to an average of 22 ±3.5 (standard deviation) in the same counties during the control periods (p = 0.02). No difference was observed for the one week period (94 compared to 79.2 ±12.4,p = 0.28). No difference was observed in the number of sudden cardiac deaths in the 48-hours or one-week following the terrorist attacks compared to control periods.

Conclusions:

A local disaster caused by a naturally occurring hazard, but not a geographically remote human disaster, was associated with an increased risk of sudden cardiac death. A better understanding of the underlying mechanisms may have implications for prevention of sudden cardiac death.

Effects of acute exercise on fibrinolysis and coagulation in patients with coronary artery disease

Acute physical exertion may trigger an acute coronary syndrome. Furthermore, acute physical exercise may influence hemostatic markers in healthy individuals. However, the effect of acute exercise on blood fibrinolysis and coagulation in patients with coronary artery disease (CAD) is still not well understood. Nineteen untrained patients with angiographically proven CAD (age, 58 +/- 9 years, 12 males), and 25 age- and sex-matched controls without CAD (age, 56 +/- 6 years, 16 males) underwent a treadmill exercise test. Global fibrinolytic capacity (GFC) and prothrombin fragment 1 + 2 (F 1 + 2) levels were measured before exercise, at peak exercise, and 2 hours after recovery. There were no differences between the groups with respect to left ventricular ejection fraction, history of hypertension, body mass index, and serum lipids. Before exercise, GFC was significantly lower in patients with CAD when compared with controls (1.40 +/- 0.43 versus 3.28 +/- 1.19 microg/mL, respectively; P < 0.001). In patients with CAD, F 1 + 2 levels were significantly higher than those of controls (1.15 +/- 0.43 versus 0.79 +/- 0.10 nmol/L, respectively; P = 0.002). In both study groups, GFC levels increased significantly at peak exercise and decreased to baseline values 2 hours after recovery. At peak exercise, F 1 + 2 levels significantly increased in both study groups. However, while F 1 + 2 levels of controls decreased to baseline values 2 hours after recovery (0.79 +/- 0.10 versus 0.80 +/- 0.10 nmol/L; P > 0.05), F 1 + 2 levels of patients with CAD were still significantly elevated (1.15 +/- 0.43 versus 1.84 +/- 0.06 nmol/L; P = 0.002). Acute exercise increases coagulation and fibrinolysis both in untrained subjects with and without CAD. However, in patients with CAD, the equilibrium between fibrinolysis and coagulation during peak exercise is disturbed in favor of coagulation after recovery.

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.

Behavioral and emotional triggers of acute coronary syndromes: a systematic review and critique

OBJECTIVE

The objective of this study was to review the evidence that behavioral and emotional factors are triggers of acute coronary syndromes.

METHOD

Systematic review of the published literature from 1970 to 2004 of trigger events, defined as stimuli or activities occurring within 24 hours of the onset of acute coronary syndromes.

RESULTS

There is consistent evidence that physical exertion (particularly by people who are not normally active), emotional stress, anger, and extreme excitement can trigger acute myocardial infarction and sudden cardiac death in susceptible individuals. Many triggers operate within 1 to 2 hours of symptom onset. There are methodologic limitations to the current literature, including sampling, retrospective reporting, and presentation biases, the role of memory decay and salience, and reverse causation because of silent prodromal events.

CONCLUSIONS

Behavioral and emotional factors are probable triggers of acute coronary syndromes in vulnerable individuals, and the pathophysiological processes elicited by these stimuli are being increasingly understood. The benefits to patients of knowledge to these processes have yet to accrue.

Inhibition by combined therapy with ticlopidine and aspirin of enhanced platelet aggregation during physical exercise in patients with coronary artery disease

BACKGROUND

Strenuous exercise can be a major trigger for coronary thrombosis and it enhances platelet aggregation.

METHODS

We evaluated the effect of antiplatelet therapy on shear stress-induced platelet aggregation (SIPA), in addition to agonist-induced aggregation, before and immediately after ergometer exercise in patients with stable coronary artery diseases (CAD). Forty-eight patients with stable CAD were randomly distributed into 3 groups: no antiplatelet drug (patient control, n = 16), aspirin (ASA) monotherapy (n = 16), and combined therapy with ticlopidine (TIC) and ASA (n = 16).

RESULTS

There were significant increases in not only adenosine phosphate (ADP)- and collagen-induced platelet aggregation but also in SIPA during exercise by the patient control group. ASA monotherapy did not attenuate the enhanced ADP-induced aggregation nor SIPA. Combined ASA + TIC therapy significantly inhibited SIPA as well as ADP-induced aggregation both before and after exercise. Significant increases in levels of plasma von Willebrand factor (vWF) occurred during exercise, and these antiplatelet therapies had no apparent effect on increased vWF levels during exercise. Exercise induced a significant increase in the plasma thrombin-antithrombin III complex level with no significant changes in the level of plasmin-plasmin inhibitor complex level in all 3 groups.

CONCLUSIONS

Combined therapy with ASA + TIC effectively inhibited increased platelet aggregability in response to acute exercise, with no effects on coagulant or fibrinolytic potentials in patients with CAD. The data suggest that TIC combined with ASA may be superior to ASA alone in preventing acute coronary events during exercise in patients with coronary atherosclerotic disease.

Utility of mechanical rheolysis as an adjunct to rescue angioplasty and platelet inhibition in acute myocardial infarction and cardiogenic shock: a case report

We describe the value of mechanical rheolysis as an adjunct to rescue angioplasty and platelet glycoprotein IIb/IIIa receptor inhibition in a patient with acute myocardial infarction and cardiogenic shock in whom the severity of the intracoronary thrombus burden precluded restoration of antegrade coronary flow by conventional balloon angioplasty and stenting.

Increased platelet aggregability in response to shear stress in acute myocardial infarction and its inhibition by combined therapy with aspirin and cilostazol after coronary intervention

Although antiplatelet therapy with a specific inhibitor of phosphodiesterase-3 cilostazol improves stent patency compared with use of aspirin (ASA) alone, the specific role of cilostazol on platelet aggregation in patients with acute myocardial infarction (AMI) is less well understood. Thirty-six patients with AMI who were successfully treated with primary angioplasty were randomized to 3 antiplatelet regimens: ASA alone (n = 12), ASA + ticlopidine (n = 12), and ASA + cilostazol (n = 12). We measured shear stress-induced platelet aggregation (SIPA) using a modified cone-plate viscometer on admission and on day 7, and evaluated the inhibitory effects of combination therapy with ASA + cilostazol on SIPA. Compared with cases of stable coronary artery disease, significant increases in SIPA and plasma von Willebrand factor activity were observed in patients with AMI before they received antiplatelet therapy. On day 7 after primary angioplasty, ASA did not inhibit SIPA (65 +/- 15% vs 57 +/- 11%, p = 0.086), whereas both combination therapies of ASA + ticlopidine and ASA + cilostazol significantly inhibited SIPA in patients with AMI (ASA + ticlopidine: 61 +/- 15% vs 45 +/- 13%, p <0. 0001; ASA + cilostazol: 64 +/- 14% vs 43 +/- 9%, p <0.005). There was a significant correlation of SIPA with adenosine diphosphate (ADP)-induced platelet aggregation (r = 0.412, p = 0.003) and with plasma von Willebrand factor activity (r = 0.461, p = 0.0008). These data suggest that patients with AMI have increased platelet aggregability in response to high shear stress. Combined antiplatelet therapy with ASA + cilostazol appears to be as effective as therapy with ASA + ticlopidine for reducing SIPA in patients with AMI who are undergoing primary angioplasty.

Analysis of human error in nursing care

Analysis of reports about incidental and accidental events in nursing care were made using a reliability engineering method. Unnatural working hours, such as evening duty, night duty falling next to a holiday, two consecutive night-duty shifts, and two consecutive evening-duty shifts were major factors in the occurrence of errors. In a mixed-division ward (a ward containing patients belonging to different divisions), rule-based errors happened more frequently than in a single-division ward. Also, less experienced nursing staffs made errors more frequently than experienced nursing staffs.

Pathophysiology of acute coronary syndromes leading to acute myocardial infarction

Acute coronary syndromes, including unstable angina, myocardial infarction, and sudden death, account for more than 250,000 deaths annually. They are the manifestation of a progressive atherosclerotic process, which culminates in the rupture of atherosclerotic plaques and the formation of mural thrombi. This article reviews recent and current research, which has shed light on key events and evolutionary processes leading to acute coronary syndromes. The article details the development of vulnerable plaques, factors that promote plaque rupture, and triggering events related to plaque rupture. Also discussed are sequelae of acute coronary syndromes, including Q wave and non-Q wave infarction and left ventricular remodeling.

Anger expression and incident stroke: prospective evidence from the Kuopio ischemic heart disease study

BACKGROUND AND PURPOSE

High levels of anger are associated with an increased risk of coronary heart disease and hypertension, but little is known about the role of anger in stroke risk.

METHODS

Anger expression style and risk of incident stroke were examined in 2074 men (mean age, 53.0+/-5.2 years) from a population-based, longitudinal study of risk factors for ischemic heart disease and related outcomes in eastern Finland. Self-reported style of anger expression was assessed by questionnaire at baseline. Linkage to the FINMONICA stroke and national hospital discharge registers identified 64 first strokes (50 ischemic) through 1996. Average follow-up time was 8.3+/-0.9 (mean+/-SD) years.

RESULTS

Men who reported the highest level of expressed anger were at twice the risk of stroke (relative hazard, 2.03; 95% CI, 1.05 to 3.94) of men who reported the lowest level of anger, after adjustments for age, resting blood pressure, smoking, alcohol consumption, body mass index, low-density and high-density lipoprotein cholesterol, fibrinogen, socioeconomic status, history of diabetes, and use of antihypertensive medications. Additional analysis showed that these associations were evident only in men with a history of ischemic heart disease (n=481), among whom high levels of outwardly expressed anger (high anger-out) predicted >6-fold increased risk of stroke after risk factor adjustment (relative hazard, 6.87; 95% CI, 1.50 to 31.4). Suppressed anger (anger-in) and controlled anger (anger-control) were not consistently related to stroke risk.

CONCLUSIONS

This is the first population-based study to show a significant relationship between high levels of expressed anger and incident stroke. Additional research is necessary to explore the mechanisms that underlie this association.

Circadian blood pressure and heart rate rhythms in mice

The circadian pattern of mean arterial pressure (MAP) and heart rate (HR) was measured in C57BL mice with carotid arterial catheters. Cardiovascular parameters were recorded continuously with a computerized monitoring system at a sampling rate of 100 Hz. The tethered animals were healthy, showing stabilized drinking and eating patterns within 2 days of surgery and little loss of body weight. Analysis of the 24-h pattern of MAP and HR was conducted using data from 3-6 consecutive days of recording. A daily rhythm of MAP was evident in all mice, with group mean dark and light values of 101.4 +/- 7.3 and 93.1 +/- 2.9 mmHg, respectively. The group mean waveform was bimodal, with peak values evident early and late in the dark period, and a trough during the middle of the light period. The phase of maximum and minimum values showed low within-group variance. Mean heart rate was greater at night than during the day (561.9 +/- 22.7 vs. 530.3 +/- 22.3 beats/min). Peak values generally occurred at dark onset, and minimum values during the middle of both the dark and the light periods. We conclude that it is possible to perform measurements of circadian cardiovascular parameters in the mouse, providing new avenues for the investigation of genetic models.