C-reactive protein elevation and early outcome in patients with unstable angina pectoris

Targeting cardiovascular inflammation: next steps in clinical translation

Systemic vascular inflammation plays multiple maladaptive roles which contribute to the progression and destabilization of atherosclerotic cardiovascular disease (ASCVD). These roles include: (i) driving atheroprogression in the clinically stable phase of disease; (ii) inciting atheroma destabilization and precipitating acute coronary syndromes (ACS); and (iii) responding to cardiomyocyte necrosis in myocardial infarction (MI). Despite an evolving understanding of these biologic processes, successful clinical translation into effective therapies has proven challenging. Realizing the promise of targeting inflammation in the prevention and treatment of ASCVD will likely require more individualized approaches, as the degree of inflammation differs among cardiovascular patients. A large body of evidence has accumulated supporting the use of high-sensitivity C-reactive protein (hsCRP) as a clinical measure of inflammation. Appreciating the mechanistic diversity of ACS triggers and the kinetics of hsCRP in MI may resolve purported inconsistencies from prior observational studies. Future clinical trial designs incorporating hsCRP may hold promise to enable individualized approaches. The aim of this Clinical Review is to summarize the current understanding of how inflammation contributes to ASCVD progression, destabilization, and adverse clinical outcomes. We offer forward-looking perspective on what next steps may enable successful clinical translation into effective therapeutic approaches-enabling targeting the right patients with the right therapy at the right time-on the road to more individualized ASCVD care.

Comparison of high-sensitivity C-reactive protein vs. C-reactive protein for diagnostic accuracy and prediction of mortality in patients with acute myocardial infarction

BACKGROUND

The role of chronic inflammation in the pathogenesis of atherosclerosis has been unequivocally proven. However, the prognostic impact of C-reactive protein, a marker of inflammatory response in patients with acute myocardial infarction has not been fully clarified. Furthermore, there is no direct comparison of the diagnostic accuracy of C-reactive protein and high sensitivity C-reactive protein in the acute myocardial infarction population.

METHODS

In this prospective observational cohort study, 344 patients with acute myocardial infarction were enrolled. All-cause mortality was a primary endpoint. Patients were followed prospectively for a median of six years.

RESULTS

The correlation between high sensitivity C-reactive protein and C-reactive protein (r = 0.99; P < 0.001) and the diagnostic accuracy (98.6%) was high. The ROC analysis revealed that C-reactive protein and high sensitivity C-reactive protein had a low AUC for prediction of mortality (C-reactive protein: 0.565, 95% CI [0.462-0.669], vs. high sensitivity C-reactive protein: 0.572, 95% CI [0.470-0.675]) or major adverse cardiac events (C-reactive protein: AUC 0.607, 95% CI [0.405-0.660], vs. high sensitivity C-reactive protein: AUC 0.526, 95% CI [0.398-0.653]) when assessed at time point of acute myocardial infarction. In contrast, longitudinal inflammatory risk assessment with serial C-reactive protein measurements in the stable phase of the disease revealed a 100% specificity, 100% negative predictive value, 32% sensitivity and 12% positive predictive value of C-reactive protein to predict long-term mortality. The Kaplan Meier analysis showed a significant survival benefit for patients at low residual inflammatory risk (P = 0.014).

CONCLUSION

C-reactive protein and high sensitivity C-reactive protein provide a similar diagnostic accuracy, highlighting that C-reactive protein might replace high sensitivity C-reactive protein in routine assessments. Furthermore, low inflammatory status during the stable phase after acute myocardial infarction predicts favourable six-year survival.

Does C-reactive protein add prognostic value to GRACE score in acute coronary syndromes?

Background

The incremental prognostic value of plasma levels of C-reactive protein (CRP) in relation to GRACE score has not been established in patients with acute coronary syndrome (ACS) with non-ST segment elevation.

Objective

To test the hypothesis that CRP measurements at admission increases the prognostic value of GRACE score in patients with ACS.

Methods

A total of 290 subjects, consecutively admitted for ACS, with plasma material obtained upon admission CRP measurement using a high-sensitivity method (nephelometry) were studied. Cardiovascular outcomes during hospitalization were defined by the combination of death, nonfatal myocardial infarction or nonfatal refractory angina.

Results

The incidence of cardiovascular events during hospitalization was 15% (18 deaths, 11 myocardial infarctions, 13 angina episodes) with CRP showing C-statistics of 0.60 (95% CI = 0.51-0.70, p = 0.034) in predicting these outcomes. After adjustment for the GRACE score, elevated CRP (defined as the best cutoff point) tended to be associated with hospital events (OR = 1.89, 95% CI = 0.92 to 3.88, p = 0.08). However, the addition of the variable elevated CRP in the GRACE model did not result in significant increase in C-statistics, which ranged from 0.705 to 0.718 (p = 0.46). Similarly, there was no significant reclassification of risk with the addition of CRP in the predictor model (net reclassification = 5.7 %, p = 0.15).

Conclusion

Although CRP is associated with hospital outcomes, this inflammatory marker does not increase the prognostic value of the GRACE score.

Inflammatory biomarkers, death, and recurrent nonfatal coronary events after an acute coronary syndrome in the MIRACL study

Background

In acute coronary syndromes, C‐reactive protein (CRP) strongly relates to subsequent death, but surprisingly not to recurrent myocardial infarction. Other biomarkers may reflect different processes related to these outcomes. We assessed 8 inflammatory and vascular biomarkers and the risk of death and recurrent nonfatal cardiovascular events in the 16 weeks after an acute coronary syndrome.

Methods and Results

We measured blood concentrations of CRP, serum amyloid A (SAA), interleukin‐6 (IL‐6), soluble intercellular adhesion molecule (ICAM), soluble vascular cell adhesion molecule (VCAM), E‐selectin, P‐selectin, and tissue plasminogen activator antigen (tPA) 24 to 96 hours after presentation with acute coronary syndrome in 2925 subjects participating in a multicenter study. Biomarkers were related to the risk of death, and recurrent nonfatal acute coronary syndromes (myocardial infarction or unstable angina) over 16 weeks using Cox proportional hazard models. On univariate analyses, baseline CRP (P=0.006), SAA (P=0.012), and IL‐6 (P<0.001) were related to death, but not to recurrent nonfatal acute coronary syndromes. VCAM and tPA related to the risk of death (P<0.001, P=0.021, respectively) and to nonfatal acute coronary syndromes (P=0.021, P=0.049, respectively). Adjusting for significant covariates reduced the strength of the associations; however, CRP and SAA continued to relate to death.

Conclusions

In acute coronary syndromes, the CRP inflammatory axis relates to the risk of death and may reflect myocardial injury. VCAM and tPA may have greater specificity for processes reflecting inflammation and thrombosis in the epicardial arteries, which determine recurrent coronary events.

Clinical utility of C-reactive protein measured at admission, hospital discharge, and 1 month later to predict outcome in patients with acute coronary disease. The RISCA (recurrence and inflammation in the acute coronary syndromes) study

OBJECTIVES

This study was designed to prospectively determine, in patients with an acute coronary syndrome, whether the inflammatory marker, C-reactive protein (CRP), measured at hospital admission, discharge, and 1 month later has incremental value to predict outcomes at 1 year.

BACKGROUND

The clinical utility of CRP measurements in patients with acute coronary syndromes remains uncertain. Limitations of previous studies have been retrospective design and incomplete adjustment for readily available clinical prognosticators.

METHODS

The CRP marker was measured at admission, hospital discharge, and 1 month later in consecutive patients hospitalized for acute coronary syndromes in 8 tertiary and secondary hospitals. The primary outcome was a composite of death, nonfatal myocardial infarction (MI), and unstable angina (UA) with electrocardiogram (ECG) changes at 1 year.

RESULTS

A total of 1,210 patients, age 62 +/- 12 years, 64% with acute myocardial infarction (MI) and 36% with unstable angina (UA), were recruited. At 1 year, the primary outcome occurred in 142 patients (11.7%) and included 58 deaths (4.8%), 79 nonfatal MIs (6.5%), and 26 UA episodes with ECG changes (2.1%). The unadjusted odds ratios (ORs) (95% confidence intervals) of CRP values at admission, hospital discharge, and 1 month later for the occurrence of the primary outcome were 1.20 (1.06 to 1.36), 0.98 (0.85 to 1.14), and 1.23 (1.00 to 1.50), respectively. After multivariate adjustment, ORs were 1.04 (0.91 to 1.20), 0.90 (0.77 to 1.06), and 1.12 (0.93 to 1.34), respectively. The individual components of the primary outcome were also not independently associated with any of the 3 CRP measurements.

CONCLUSIONS

The modest predictive ability of CRP following admission for an acute coronary syndrome disappeared after adjusting for common clinical variables. This large prospective study does not support the incremental value of measuring CRP in this clinical setting.

C-reactive protein: the harbinger of cardiovascular diseases

Coronary heart disease remains the major cause of mortality and morbidity in the United States and other western countries despite major advances in its treatment. During the last decades, many markers of coronary artery disease have been found which help predict future risk of cardiovascular events. High-sensitivity C-reactive protein has been studied extensively and was seen to be associated with a higher risk of cardiovascular events in patients with acute coronary syndromes and/or peripheral artery disease. Discussed in this review is the latest literature about this marker and its association with cardiovascular disease, as well as the latest therapeutic options available.

Critical appraisal of C-reactive protein throughout the spectrum of cardiovascular disease

Clinicians involved in the care of patients with cardiovascular conditions have recently been confronted with an important body of literature linking inflammation and cardiovascular disease. Indeed, the level of systemic inflammation as measured by circulating levels of C-reactive protein (CRP) has been linked to prognosis in patients with atherosclerotic disease, congestive heart failure, atrial fibrillation, myocarditis, aortic valve disease and heart transplantation. In addition, a number of basic science reports suggest an active role for CRP in the pathophysiology of cardiovascular diseases. This article explores the potential role of CRP in disease initiation, progression, and clinical manifestations and reviews its role in the prediction of future events in clinical practice. Therapeutic interventions to decrease circulating levels of CRP are also reviewed.

C-reactive protein as a marker for active coronary artery disease in patients with chest pain in the emergency room

BACKGROUND

Markers of inflammation, such as C-reactive protein (CRP), were found to be related to risk for cardiovascular disease (CVD) events in patients with angina pectoris. In addition, recent studies have shown that, in the case of atherosclerosis, increased CRP concentration reflects the inflammatory condition of the vascular wall.

HYPOTHESIS

The study was undertaken to determine whether CRP levels in individuals with chest pain attending the emergency room (ER) may be used as a marker of active CVD.

METHODS

Serum CRP level was measured in 226 of 326 consecutive patients (128 men, 98 women; mean age 61.3 +/- 5.9 years; range 19-87 years) referred to the ER with chest pain. The decision whether to admit orrelease the subjects was determined without taking the CRP level into account. Follow-up was then performed for 1 year.

RESULTS

Eighty-four patients were admitted to the hospital. Of these, 9 with acute coronary syndrome (ACS) had very high levels of CRP (25-40 mg/l), 35 had had an acute coronary event within the preceding 3 months, with levels of CRP 14-20 mg/l. Only eight patients with nonsignificant CVD had elevated CRP levels. Twenty-eight subjects who were released from the ER had elevated CRP levels (7-14 mg/l); 8 of these, in addition to 4 subjects with normal CRP levels, had a late coronary event.

CONCLUSION

This study indicates that in patients referred to the ER with chest pain and no other indication for hospitalization, a normal level of CRP suggests safe release. Most hospitalized patients with normal CRP will not have acute coronary syndrome. Patients who will develop early coronary events have very high CRP levels. High serum CRP level, after excluding other inflammatory sources, was proven to be a sensitive diagnostic and prognostic marker for significant coronary disease.

Predischarge C-reactive protein and 1-year outcome after acute coronary syndromes

PURPOSE

To investigate the relationship between high-sensitivity C-reactive protein and cardiovascular events following acute coronary syndrome.

METHODS

This nationwide, cross-sectional, prospective study involved 439 patients with an acute coronary syndrome who presented to the hospital within 24 hours of symptom onset. Patients with a concomitant inflammatory process were excluded. Predischarge C-reactive protein samples were measured using a high-sensitivity method in a core laboratory. The outcome was the composite of death, acute myocardial infarction, stroke/transient ischemic attack, urgent hospitalization for unstable angina, and urgent revascularization within 1 year.

RESULTS

At 1 year, event rates were 10.2% for the lowest, 8.2% for the middle, and 11.0% for the highest C-reactive protein tertiles (P = .75) with similar event-free survival (P = .70). The hazard ratio (HR) for event rates between the highest and lowest tertiles was 1.10 (95% confidence interval [CI]: 0.54 to 2.20) There was marked overlap of C-reactive protein values between patients with and without events (median [interquartile range]: 8.39 [3.27 to 32.63] vs 9.55 [4.07 to 24.02], respectively; P = .91). C-reactive protein was not an independent predictor of 1-year events (HR for highest tertile: 1.19; 95% CI: 0.58 to 2.43; P = .64) and performed poorly on receiver operating characteristic curve analysis (C statistic = 0.51).

CONCLUSION

Predischarge high-sensitivity C-reactive protein level is a poor predictor of cardiovascular events at 1 year after acute coronary syndrome.

CRP is or is not a reliable marker of ischaemic heart disease?

In recent years a growing body of evidence has emphasized the role of C-reactive protein (CRP) as a marker of future cardiovascular events. CRP is a pentameric molecule widely utilized as a marker of infections and inflammation. The evidence that inflammation plays an important role in the pathogenesis of coronary artery disease and in plaque destabilization has lead to use of CRP as a marker of cardiovascular disease as well. First described as a component of the inflammatory pathway in acute coronary syndromes, CRP has been consistently found to be associated with the risk of future events in no-ST elevation acute coronary syndromes, independently of other risk factors, including troponine. Subsequently CRP has been described as a powerful marker of risk of future events in large populations of apparently healthy subjects. So far there is very little doubt that CRP represents a reliable marker of cardiovascular events, but some issues remain unanswered such as why CRP is a good marker of cardiovascular events and whether or not a better inflammatory marker exists. It must be stressed that CRP, because of its analytical and biological properties and the large amount of available data, is the only inflammatory marker accepted for clinical use.

CDC/AHA Workshop on Markers of Inflammation and Cardiovascular Disease

Inflammation is a recognized key component of acute coronary syndromes. Such pathogenetic achievement has led to the use of inflammatory cells and proteins as prognostic markers in these syndromes. A number of markers have been proposed, including proinflammatory cytokines such as interleukin-6, interleukin-1RA, and tumor necrosis factor-α, adhesion molecules such as intracellular adhesion molecule-1 and vascular adhesion molecule-1 and markers of cell activation. Although all are of scientific interest, the clinical use of these markers is limited by their high cost, low availability, and unfavorable biological profile. Conversely, common markers of inflammation such as C-reactive protein (CRP), the prototypic acute phase protein, and to a lesser extent fibrinogen, have been proven to be reliable and important markers of risk in ischemic heart disease. CRP, in particular, has been found to be associated with short- and long-term prognosis in acute coronary syndromes, including ST-elevation myocardial infarction, and in stable angina, and to predict the risk of restenosis and major events, including death, after revascularization procedures. CRP has been consistently found to be independent from other risk factors and to have an incremental value beyond the common risk factors and biochemical markers of risk, including troponin. Whether CRP also should be used as a guide to therapy is still a matter of discussion that deserves further, properly designed studies.

C reactive protein for risk stratification in acute coronary syndromes? Verdict: unproven

Although C reactive protein is intimately involved with the pathogenic mechanisms that drive acute coronary syndromes, there is no evidence that it is helpful for identifying patient groups who might benefit from particular treatment strategies

Rapid assessment of patients with non-ST-segment elevation acute chest pain: troponins, inflammatory markers, or perfusion imaging?

BACKGROUND

Perfusion imaging during or soon after pain has been shown to provide diagnostic and prognostic information in patients with suspected angina. Measurement of troponin I (TnI) and troponin T (TnT) provides similar information but only several hours after onset of pain. The role of inflammatory markers in this setting is less clear.

METHODS AND RESULTS

We prospectively studied 80 nonconsecutive patients using gated technetium 99m sestamibi single photon emission computed tomography (MIBI), TnT, TnI, C-reactive protein, IL-6, and tumor necrosis factor alpha. Of these patients, 50 (63%) had abnormal MIBI, 13 (17%) had elevated TnT, 17 (21%) had elevated TnI, and C-reactive protein, IL-6, and tumor necrosis factor alpha were raised in 46 (58%), 14 (18%), and 29 (37%), respectively. Myocardial infarction was the presenting event in 13 patients (16%), and 23 (34%) of those without index myocardial infarction sustained a cardiovascular event during follow-up. MIBI, TnT, TnI, and electrocardiogram all had similar negative predictive values for index myocardial infarction (97%, 97%, 95%, and 97%, respectively). However, only MIBI had a high negative predictive value for the prediction of subsequent events during follow-up (86%). TnT and MIBI were the only independent predictors of all events. Inflammatory markers provided no useful additional prognostic information.

CONCLUSIONS

The combination of TnT and MIBI is the best model for early prediction of cardiac events in patients with acute chest pain.

Use of risk stratification to identify patients with unstable angina likeliest to benefit from an invasive versus conservative management strategy

OBJECTIVES

This study was designed to determine whether patient characteristics collected at presentation can identify which patients benefit from immediate coronary angiography and revascularization.

BACKGROUND

Risk stratification may offer a method for identifying which patients with unstable angina or non-Q-wave myocardial infarction (NQMI) are likeliest to benefit from invasive management strategies.

METHODS

The analysis was based on data from a randomized controlled trial that enrolled 1,473 patients presenting with unstable angina or NQMI who were randomly assigned to an early invasive or early conservative (medical) management strategy. We constructed a risk-stratification score for each patient based on adjusted odds ratios for clinical variables likely to predict adverse outcomes. We stratified all trial subjects by their risk scores and studied the rates of death or myocardial infarction (MI) of the early invasive management strategy in each stratum.

RESULTS

The final multivariate model included older age, ST segment depression on presentation, history of complicated angina before presentation, and elevation in baseline creatine kinase-MB fraction. Although patients with a higher risk score had an increased rate of death or MI within 42 days and 365 days (p < 0.001) in both management strategies, early invasive management for patients in the high and very high risk categories was associated with a lower rate of death or MI within 42 days compared with conservative management. No such benefit was seen in patients in the larger group of patients in the very low, low or moderate risk categories (p = 0.03 for the interaction between risk category and management assignment).

CONCLUSIONS

Risk stratification may be an effective method for identifying those patients with unstable angina or NQMI most likely to benefit from early invasive management. Selective use of early invasive management can have a substantial impact in reducing morbidity and mortality in higher risk patients, but may not be warranted in lower risk patients.

Cardiac markers and risk stratification: an integrated approach

Risk stratification of patients with acute coronary syndromes (ACS) is pivotal for correct allocation of health resources and for maximizing the benefit of available treatment modalities. However, clinical and electrocardiographic indicators of high risk lack sufficient sensitivity for the detection of major cardiac events. The complementary information provided by the measurement of different biomarkers is believed to be very useful. Specifically, elevations of cardiac troponin I (cTnI) and T (cTnT) are strongly associated with a high-risk profile both at short- and long-term. This has been definitely demonstrated in many studies as well as in cumulative meta-analysis. The role of different biomarkers, such as those reflecting activation of hemostasis and the presence of inflammation, is however less defined. At the moment, no study has prospectively evaluated these biomarkers in the whole spectrum of unselected patients with ACS. It is also unclear whether these biomarkers add independent prognostic value to the clinical and electrocardiographic indicators of adverse outcome and whether they offer additional information when compared to each other. The Early Prognostic Value of Biochemical Markers of Myocardial Damage, Activation of Hemostatic Mechanism and Inflammation in Acute Ischemic Syndromes (EMAI) study has been prospectively designed to solve these issues. In this study, we have evaluated the prognostic value of cTnI and cTnT, D-dimer, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT) and C-reactive protein (CRP) in patients with ACS at the time of admission. We have enrolled in 31 Italian Coronary Care Units 1971 patients with rest anginal pain within 12 h from admission and electrocardiographic evidence of myocardial ischemia. Of these, 730 patients resulted to have ST-segment elevation myocardial infarction eligible for a reperfusion strategy and 1241, an acute coronary syndrome without persisting ST-segment elevation. Primary outcome measure of the study is the composite of death and non-fatal MI within 30 days from admission, which has occurred in 8.9% of the study population.

C-reactive protein, fibrinogen, interleukin-6 and tumour necrosis factor-alpha in the prognostic classification of unstable angina pectoris

BACKGROUND

Inflammatory process has been found to play an important role in the pathogenesis of coronary heart disease (CHD) and in the prognosis of CHD patients. AIM. The aim of this study was to investigate the prognostic value of C-reactive protein (CRP), fibrinogen, interleukin (IL)-6 and tumour necrosis factor-alpha (TNF-alpha) in patients with unstable angina pectoris (UAP), including factor analysis to assess their joint effects.

METHODS

The study comprised 263 consecutive patients (159 men, 104 women; median age 68 years) with UAP. Blood samples for the acute-phase protein and cytokine determinations were drawn on admission.

RESULTS

Coronary mortality during the median follow-up time of 17 months was 6-fold higher in the highest tertile for CRP and IL-6 and 3.5-fold higher in the highest tertile for fibrinogen and TNF-alpha than in the respective combined lower tertiles. Factor analysis produced two underlying factors, ie the 'inflammation' factor, including CRP, fibrinogen and IL-6, and the 'injury' factor, including troponin T, creatine kinase MB mass and TNF-alpha. In Cox models, both of these factors were independent predictors of the risk of coronary death and major coronary events (coronary death or nonfatal myocardial infarction).

CONCLUSIONS

Elevated levels of acute-phase proteins and cytokines, particularly CRP and IL-6, are strong predictors of the risk of serious coronary events in patients with UAP.

Is Inflammation Related to the Clinical Severity of Unstable Angina?

The present study determined the white blood cell (WBC) count and the serum C-reactive protein (CRP) level in 27 patients with coronary spastic angina, 16 with Braunwald class IB unstable angina (UA) and 13 with Braunwald class IIIB. The relationship between the clinical presentation of UA and the requirement for emergency percutaneous transluminal coronary angioplasty (PTCA) was examined, and in patients with medically refractory angina, the determining factor among the clinical manifestations of angina was also investigated. In the acute phase, the WBC count and the serum CRP level were significantly higher in patients with Braunwald class IIIB than in those with coronary spastic angina or Braunwald class IB UA (p<0.001). In the Braunwald class IIIB group, a significantly higher rate of patients required emergency PTCA than that of the coronary spastic angina group (p<0.01). Patients with medically refractory angina had a significantly higher WBC count and higher serum CRP level on admission, and the WBC count on admission was independently associated with medically refractory angina by multivariate analysis (p<0.05). Inflammation may play a major pathological role in the rapid development of acute coronary syndrome.

Effect of leukocytosis at initial examination on prognosis in patients with primary unstable angina

BACKGROUND

Leukocytosis with acute myocardial infarction at initial examination predicts adverse prognosis, but it is unknown whether it predicts outcome in patients with primary unstable angina.

METHODS AND RESULTS

We studied 414 consecutive patients with unstable angina admitted through the emergency department to telemetry and intensive care units of an urban academic hospital. To study primary unstable angina, we excluded 134 patients with precipitants (eg, urosepsis, pneumonia) that may cause leukocytosis. Of 280 patients, 96 (34%) had leukocytosis (leukocyte count >10,000 per microL) at initial examination. A total of 30 patients (11%) died and 47 (17%) died or had nonfatal myocardial infarction within 12 months of initial examination. In a univariate Cox model, patients with leukocytosis had a hazard ratio (HR) of 2.6 (95% confidence interval [CI] 1.3-5.4) for death by 1 year. In a multivariate Cox model the only significant predictors of 1-year death were congestive heart failure at initial examination (HR 7.8; 95% CI 2.8-22) and elevated creatinine (HR 2.7; 95% CI 1.3-5.7); in this model, the relation between leukocytosis and prognosis was markedly attenuated (HR 1.4; 95% CI 0.6-2.9). The adjusted HR for leukocytosis was 1.3 (95% CI 0. 7-2.3) for death or nonfatal MI by 1 year.

CONCLUSIONS

Leukocytosis at initial examination is associated with adverse prognosis in patients with primary unstable angina. However, the association is confounded by other important predictors of prognosis. Leukocytosis may be a marker of stress associated with more severe cases of unstable angina or comorbid conditions.

Serum C-reactive protein and self-reported stroke: findings from the Third National Health and Nutrition Examination Survey

C-reactive protein may predict the risk of coronary heart disease, but its association with stroke has not been well studied. We used data from the Third National Health and Nutrition Examination Survey, conducted from 1988 to 1994, to examine the association between serum C-reactive protein concentrations and self-reported past history of stroke among 8850 US men and women aged >/=40 years. The unadjusted geometric mean of C-reactive protein concentration was higher among participants with stroke than those without stroke (0. 45+/-0.02 versus 0.32+/-0.01, P<0.001). After adjusting for age, sex, race or ethnicity, education, smoking status, systolic blood pressure, serum cholesterol, high density lipoprotein cholesterol, history of diabetes mellitus, body mass index, and physical activity, the odds ratio for stroke among participants with C-reactive protein concentrations >/=0.55 mg/dL compared with participants with concentrations </=0.21 mg/dL was 1.71 (95% CI 1.11 to 2.64 [odds ratio per mg/dL 1.19, 95% CI 1.05 to 1.34]). These cross-sectional data support findings from other studies suggesting that C-reactive protein concentration may be a risk factor or marker for stroke in the US population.

Markers of inflammation as predictors in cardiovascular disease

Recent research suggests that inflammation in the coronary arteries may be intimately involved in the development of atherosclerosis and its associated acute coronary syndromes. Experimental and clinical studies based on the biochemical markers of inflammation and vascular perturbation in plasma as well as in atherosclerotic tissue have provided substantial evidence of ongoing inflammation in coronary heart disease. These studies have suggested a potential role for biochemical markers of inflammation in the prediction of risk for the development of coronary heart disease as well as in the prediction of adverse cardiac-related outcomes in patients with known coronary syndromes. Markers of inflammation appear to offer risk prediction information that is independent of, and possibly complementary to, traditional risk factors for the development of cardiovascular disease. There are numerous potential markers for these inflammatory processes and their interdependence remains somewhat unclear. Clinical studies have investigated some, but not all of these markers in a critical and comparative fashion. Therefore, further well-designed prospective studies should elucidate the role of markers of inflammation in the prediction, diagnosis, and management of cardiovascular disease.

Serum C-reactive protein and fibrinogen concentrations and self-reported angina pectoris and myocardial infarction: findings from National Health and Nutrition Examination Survey III

C-reactive protein may predict the risk of cardiovascular disease, but its association with angina pectoris in the general population has not been clearly established, however. We used data from National Health and Nutrition Examination Survey III conducted from 1988-1994 to examine the associations between serum C-reactive protein and plasma fibrinogen concentrations and self-reported angina pectoris and myocardial infarction among 7,948 U.S. men and women aged 40 years and older. C-reactive protein and fibrinogen concentrations were moderately correlated (r = 0.43). After adjustment for age, sex, race or ethnicity, education, smoking status, systolic blood pressure, serum cholesterol, high-density lipoprotein cholesterol, history of diabetes mellitus, body mass index, and physical activity, fibrinogen (but not C-reactive protein) concentration was significantly associated with self-reported angina pectoris. Neither fibrinogen or C-reactive protein concentrations were significantly associated with angina pectoris when entered in the model simultaneously. C-reactive protein and fibrinogen concentrations were positively associated with myocardial infarction when entered separately into models, but only C-reactive protein concentration was significantly associated with myocardial infarction when both variables were entered simultaneously. These cross-sectional data showed a significant positive association between C-reactive protein concentration and myocardial infarction but not self-reported angina pectoris in the U.S. population.

Redefining medical treatment in the management of unstable angina

In 1994, the Agency for Health Care Policy and Research sponsored the development of guidelines for diagnosing and managing patients with unstable angina. Since their publication, several important developments have occurred. The prognostic value of biochemical assays for cardiac-specific troponins T and I have been shown in many studies. The possible role for C-reactive protein in determining prognosis deserves further investigation. Substantial clinical benefits have been obtained with intravenous inhibitors of the platelet glycoprotein (GP) IIb-IIIa receptor (abciximab, eptifibatide, tirofiban) and with one of the low-molecular-weight heparins (enoxaparin). The therapeutic potential of other low-molecular-weight heparins, direct thrombin inhibitors, and oral GP IIb-IIIa inhibitors remains to be clarified. On the basis of this evidence, consideration should be given to measuring serum levels of a cardiac troponin (either T or I) and using intravenous GP IIb-IIIa inhibitors and low-molecular-weight heparin in the standard management of patients with unstable angina.

Heat production of atherosclerotic plaques and inflammation assessed by the acute phase proteins in acute coronary syndromes

Several studies have shown that inflammation plays an important role in the pathogenesis of coronary heart disease (CHD). Serum amyloid A (SAA) and C-reactive protein (CRP) reactants of the acute phase of inflammation, have been shown to be increased in patients with CHD. Recently ex vivo studies demonstrated that some types of atherosclerotic plaques show substantially warmer regions. A catheter-based technique has been developed to measure the temperature of human arteries in vivo. Therefore, the aim of the present study was to measure the luminal surface temperature in patients with CHD and to correlate it with the acute phase proteins in order to discriminate the role of inflammation in heat production in acute coronary syndromes. Sixty patients were studied with CHD (20 with stable angina, 20 with unstable angina and 20 with acute myocardial infarction) and 20 sex- and age-matched controls without coronary artery disease, by measuring plasma levels of SAA, CRP, plasma lipids and intracoronary arterial luminal wall temperature. Intracoronary temperature was measured with a thermography catheter developed in our Institution: a thermistor probe with a temperature accuracy of 0.05 degrees C, was attached at the distal end of a long 3F polyurethane shaft. It was found that the median temperature differences at the site of the lesion from the core temperature was increased in patients with unstable angina (1.025 degrees C) and acute myocardial infarction (2.150 degrees C) compared with stable angina (0.300 degrees C), P<0.001 for each comparison. Furthermore, stable angina has increased temperature differences compared with controls (0.200 degrees C, P<0.001). There were very good correlations between CRP and SAA with the temperature (r=0.796, P=0.01 and r=0.848, P=0.01, respectively). Local heat at the site of lesion is increased in patients with acute coronary syndromes and may arise from an aggressive inflammatory response occurring in these situations. The sensitive measurement of plaque temperature as a prognostic marker may be useful in the management of coronary heart disease.

Fibrinolytic factors, serum lipid and C-reactive protein predicting cardiac events in Japanese patients with coronary atherosclerotic lesions

Although disturbances of the fibrinolytic system and serum lipid, and the presence of inflammation, may be risk factors for coronary artery disease (CAD), few reports have investigated these relationships in Japanese patients. Data on 106 patients (79 men and 27 women, mean age 62.3 years) with atherosclerotic lesions on the coronary angiogram were evaluated prospectively to identify whether the factors were useful in predicting the risk of coronary events during a follow-up of 50+/-4 months. Of the 106 patients who were followed, 11 patients had coronary events (4 acute myocardial infarction and 7 unstable angina pectoris). In univariate Cox analyses, a high level of tissue-plasminogen activator (t-PA), apolipoprotein CII, C-reactive protein (CRP), and a low level of high-density lipoprotein-cholesterol (HDL-C) was each associated with a significant increase in the risk of future cardiac events. The stepwise model of Cox proportional hazards analysis selected only a high level of t-PA and CRP as predictors of cardiac events. Controlling for any risk factor did not lower the relation between t-PA and the risk of cardiac events, whereas the relative risk of cardiac events in CRP was not significant when controlled for HDL-C. Thus, in prospective data obtained from a cohort of Japanese patients with coronary atherosclerotic lesions, the elevation of t-PA was an independent predictor of subsequent cardiac events. The prognostic role of CRP in cardiac events was related to a low level of HDL-C.

The role of C-reactive protein in cardiovascular disease risk

The genesis of an atherosclerotic plaque depends on interplay of cellular components of the immune system such as monocytes, cytokines, and cell adhesion molecules with lipids, platelets and endothelial cells. Thus, inflammation may play a pivotal role in the propagation of coronary artery disease. Several reports have linked inflammation and cardiovascular risk, particularly a novel acute inflammatory peptide, C-reactive protein (CRP), with future risk of coronary events independent of the traditional coronary artery disease risk factors. To this end, many studies suggest that CRP may be used as a marker of sub-clinical atherosclerosis and cardiovascular risk. Specifically, CRP has been positively linked to future cardiovascular events in healthy women, healthy men, elderly patients, and high-risk individuals. In addition, reports have shown associations between CRP and peripheral vascular disease and stroke. Furthermore, preliminary data suggest that the relative efficacy of secondary preventive therapies such as statin drugs and aspirin may depend on the individual patient's baseline CRP level.

Intense acute phase response in ischemic patients

The aim of this study was to estimate the qualitative and quantitative changes of acute phase proteins in patients suffering from coronary heart disease. The study was carried out on 74 patients and 12 healthy volunteers. The patients were divided into three groups as follows: patients with myocardial infarction (n=37), Group I--without heart failure, Group II--with heart failure (II-III NYHA), Group III--patients with unstable angina pectoris (n=35); controls-healthy volunteers (n=12). The immunological measurements were performed at the beginning of hospitalisation (point 0), after 4, 8, 12 and 72 h, and after 6, 9 and 12 days of hospitalisation. The concentrations of C-reactive protein (CRP), alpha1-acid glycoprotein (AGP) and alpha1-antichymotrypsin (ACT) were measured using rocket immunoelectrophoresis according to Laurell. Glycosylation profiles of AGP and ACT were determined using crossed affinity immunoelectrophoresis with Con A as ligand according to Bøg-Hansen. Between Groups I and II statistically significant differences were observed for all investigated parameters. Highest concentration values were observed for Groups II and III; for Group II they appeared earlier than for Group III. The maximal values for reactivity coefficients (AGP-RC and ACT-RC) were observed earlier than the respective maximal values of concentrations. Continuous activation occurring in unstable angina leads to a more rapid increase in the concentrations of acute phase proteins and more marked alterations in their glycosylation profiles. In a way these patients seem to be 'primed' with constant stimulation, so that they respond dramatically to the stimulus of ischemia.

Comparison of the prognostic value of C-reactive protein and troponin I in patients with unstable angina pectoris

This study assessed the prognostic value of cardiac troponin I (cTnI) and C-reactive protein (CRP) in unstable angina, and specifically in patients with angiographically proven coronary artery disease. These biochemical parameters, which are related to myocardial injury or to systemic inflammation, may help in short-term risk stratification of unstable angina. We prospectively studied 195 patients with unstable angina, 100 of whom had angiographically proven coronary artery disease (with normal creatine kinase [CK] and CK-MB mass). Serum concentrations of cTnI (N < 0.4 ng/ml) and CRP (N < 3 mg/L) were measured at admission, 12, and 24 hours later. The rate of in-hospital major adverse cardiac events (death, myocardial infarction, or emergency revascularization) was higher in patients with increased cTnI within the first 24 hours, regardless of the results of coronary angiography (23% vs 7%; p < 0.001). Conversely, events occurred at similar rates in patients with or without increased CRP. In patients with angiographic evidence of coronary artery disease, multivariate analysis showed that increased cTnI within 24 hours of admission (35 patients) was an independent predictor of major adverse cardiac events (odds ratio 6.7, range 1.7 to 27.3), but not cTnI levels at admission and CRP at 0, 12, and 24 hours. Thus, both in unselected patients with unstable angina and in patients with angiographically proven coronary artery disease, increased cTnI within 24 hours of admission, but not CRP, is a predictor of in-hospital clinical outcome. We also found a temporal link between cTnI increase and late elevation of CRP, suggesting that systemic inflammation may partially be a consequence of myocardial injury.