Acute coronary syndromes--beyond myocyte necrosis

[Natriuretic peptides and multimarker approach to risk stratification of patients with acute coronary syndromes]

NATRIURETIC PEPTIDES IN ACUTE CORONARY SYNDROMES: Brain natriuretic peptides (BNP) and N-terminal prohormone brain natriuretic peptides (N-proBNP) have been shown to provide important prognostic information in patients with acute coronary syndrome (ACS). Ischemia may be an important stimulus for BNP release. This does not imply, however, that BNP is useful for diagnosing ischemia, and BNP is unlikely to prove sensitive or specific enough for this purpose. SIGNIFICANCE OF NATRIURETIC PEPTIDES IN ASSESSING PROGNOSIS IN PATIENTS WITH ACUTE CORONARY SYNDROMES: In patients with ST-elevation and non-ST-elevation myocardial infarction, higher BNP and N-proBNP levels have been shown to predict a greater likelihood of death or heart failure, independent of other prognostic factors. THERAPEUTIC IMPLICATIONS OF BNP ELEVATION IN ACUTE CORONARY SYNDROMES: Patients with BNP or NT-proBNP elevation following ACS are clearly at high risk for death and for developement of heart failure, but specific therapeutic implications of BNP elevation have not been defined. In particular, it is not known how patients with BNP elevation should be treated considering the fact that they have normal troponin levels and no clinical evidence of heart failure. MULTIMARKER STRATEGIES FOR RISK STRATIFICATION IN ACUTE CORONARY SYNDROMES: It has been shown recently that in patients with acute coronary syndromes the risk increased sequentially among those with one, two or three elevated biomarkers. THERAPEUTIC APPLICATIONS OF CARDIAC BIOMARKERS IN ACUTE CORONARY SYNDROMES: Multimarker strategies, that incorporate panels of cardiac biomarkers, are likely to be used in the future for risk stratification and for pathophysiologically-guided treatment of patients with ACS.

Risk factors for thromboembolic events in renal failure

OBJECTIVES

To determine whether prior thromboembolic events (TE) influence current measures of hemostasis, inflammation and oxidative stress in a population at high cardiovascular risk.

BACKGROUND

Renal failure patients demonstrate a remarkably elevated incidence of TE.

METHODS

Relationships between plasma test results and prior TE history were studied in 78 diabetic and 23 non-diabetic patients with renal failure. TE were defined as myocardial infarction, stroke or vascular surgery.

RESULTS

Markers for inflammation (interleukin (IL)-6, C reactive protein (CRP)), thrombosis (fibrinogen, low molecular weight (LMW) fibrinogen, factor VII, viscosity), fibrinolysis (fibrinolytic activity, plasminogen activator inhibitor (PAI)), endothelial/platelet activity (P-selectin, von Willebrand factor (vWf)) and oxidative stress (antibody to oxidized low-density lipoprotein (LDL), advanced glycated end products) were significantly different from a healthy control population. Dialysis patients with diabetes were twice as likely to have sustained a TE (58 vs. 30%, p = 0.032). Those patients in the total group with levels above the median for IL-6 (p = 0.045), and CRP (p < 0.017) were more likely to have sustained a TE than those with levels below the median. Those diabetic patients with levels above the median for CRP were more likely to have a prior history of TE (p < 0.021). For non-diabetic patients, levels above the median of IL-6 were associated with a prior history of TE (p = 0.027). Multiple correlations for factors of inflammation, hemostasis and oxidative stress indicate that these mechanisms are not independent of one another.

CONCLUSION

Prior TE was associated with markers of inflammation a relationship that may influence the interpretation of these tests which are strongly interrelated in patients at high cardiovascular risk.

Evaluation and management of the acutely dyspneic patient: the role of biomarkers

The etiology of dyspnea can often be difficult to rapidly and accurately determine and can delay timely and appropriate therapies. The current literature reveals important diagnostic, prognostic, and therapeutic implications of several currently used biomarkers: sensitive d -dimer, myoglobin, creatine kinase-MB, cardiac troponins, and b-type natriuretic peptide. These biomarkers were found to have a high sensitivity and negative predictive value for rapidly ruling out potential serious etiologies of dyspnea, namely, pulmonary embolism (PE), acute myocardial infarction (AMI), and congestive heart failure (CHF). In the setting of a low to moderate pretest probability of PE, a negative sensitive d -dimer can rule out a PE with 97% accuracy. After 10 hours from the onset of symptoms, normal levels of myoglobin, creatine kinase-MB, and cardiac troponin I can rule out an AMI with greater than 96% accuracy. A b-type natriuretic peptide level less than 80 pg/mL can confidently rule out decompensated CHF with greater than 99% accuracy. However, no literature was found analyzing the use of these biomarkers in combination. A dyspnea biomarker panel could rapidly and accurately assist a clinician to rule out PE, AMI, and CHF. If a PE, AMI, or CHF is determined to be the cause of dyspnea, a biomarker panel could help risk stratify and help determine initial therapies. Subsequent clinical research is needed to corroborate this postulation.

Brain Natriuretic Peptide in the Management of Heart Failure

Brain natriuretic peptide (BNP), also called B-type natriuretic peptide, is a member of a family of structurally related hormones, the natriuretic peptides. Current data suggest that measurement of BNP plasma concentrations is a useful tool in the diagnosis of acute heart failure in patients presenting to an emergency department with acute dyspnea. Furthermore, BNP constitutes a promising new marker of prognosis after an acute coronary syndrome episode and in patients with chronic heart failure. Nesiritide, the human recombinant form of BNP, is a new vasodilator used in the treatment of acute heart failure that has several potential advantages over current drug therapy.

Biochemical markers of cardiac diseases

This article reviews the current contribution of the determination of biochemical markers to clinical cardiology and discusses some important developments in this field. Biochemical markers play a pivotal role in the diagnosis and management of patients with acute coronary syndrome (ACS), as witnessed by the incorporation of cardiac troponins into new international guidelines for patients with ACS and in the redefinition of myocardial infarction. Despite the success of cardiac troponins, there is still a need for development of early markers that can reliably rule out ACS from the emergency room at presentation and detect myocardial ischemia also in the absence of irreversible myocyte injury. Under investigation are two classes of indicators: markers of early injury/ischemia and markers of coronary plaque instability and disruption. Finally, with the characterization of the cardiac natriuretic peptides, Laboratory Medicine is also assuming part in the assessment of cardiac function.

C-reactive protein in acute myocardial infarction: association with heart failure

BACKGROUND

High C-reactive protein (CRP) levels have been associated with higher mortality rate in patients with acute myocardial infarction (AMI). However, it is not known whether inflammation plays a role in the time-course of heart failure (HF) in this clinical setting. Our aim was to study the nature of the relationship between CRP and HF during AMI.

METHODS

This prospective study was carried out in 269 subjects admitted to the hospital for suspected AMI. Of these, 220 had evidence of AMI. The other 49 subjects were studied as controls. CRP was assessed on the first, third, and seventh day after admission.

RESULTS

CRP was significantly higher in the patients with AMI than in the control patients (P =.001) and peaked on the third day. Among the patients with AMI, CRP was higher in patients with HF than in patients without HF (adjusted P =.008, P =.02 and P =.03 on 1st, 3rd, and 7th day, respectively). Prevalence of HF on admission was slightly higher in the subjects with first-day CRP >or=15 mg/L than in those with CRP <15 mg/L, and the between-group difference progressively increased from the first to the seventh day (P <.0001). At multivariable regression analysis, first-day log-CRP was shown to be a strong independent predictor of both HF progression (P <.0001) and left ventricular ejection fraction (P <.0001). One-year total mortality and HF-mortality rates turned out to be higher in the patients with CRP >or=85 mg/L than in those with CRP below that level (P <.0001), and log-third-day CRP was independently associated with 1-year mortality at multivariable analysis (P =.0001).

CONCLUSIONS

CRP on admission to hospital is suitable for predicting the time-course of HF in patients with AMI. Peak CRP value is a strong independent predictor of global and HF-mortality during the following year.

Cardiac troponin I (2nd generation assay) in chronic haemodialysis patients: prevalence and prognostic value

BACKGROUND

Elevated serum cardiac troponin T (cTnT) levels are frequently observed in chronic dialysis patients and have been shown to be associated with increased morbidity and mortality. The aim of this study was to determine whether cardiac troponin I (cTnI), which is less frequently elevated, has similar clinical significance.

METHODS

We studied 101 asymptomatic patients with no clinical evidence of coronary artery disease who were undergoing chronic dialytic treatment. We measured their serum cTnI levels immediately before the start of their dialysis sessions by a second-generation assay (OPUS-DADE). Our study included a year-long follow-up with trimestrial cTnI assays as well as clinical, X-ray and echocardiographic surveillance. We considered patients with serum cTnI > or =0.15 ng/ml as positive and those with levels <0.15 ng/ml as negative.

RESULTS

Among the 14 patients with high serum cTnI levels, nine (64%) suffered acute cardiac events during the 12-month follow-up. In contrast, among the 72 patients with low cTnI levels only seven (9.7%) had acute events. In another group of 15 patients with variable cTnI levels, three patients (20%) had cardiac events.

CONCLUSION

Based on these results, serum cTnI appears to be a valuable predictive marker of cardiovascular events in asymptomatic dialysis patients. For those patients who might benefit from thorough cardiac investigation and treatment, information on cTnI could be useful in preventing cardiac events.