Cumulative risk assessment in unstable angina: clinical, electrocardiographic, autonomic, and biochemical markers

A novel heart rate variability based risk prediction model for septic patients presenting to the emergency department

A quick, objective, non-invasive means of identifying high-risk septic patients in the emergency department (ED) can improve hospital outcomes through early, appropriate management. Heart rate variability (HRV) analysis has been correlated with mortality in critically ill patients. We aimed to develop a Singapore ED sepsis (SEDS) predictive model to assess the risk of 30-day in-hospital mortality in septic patients presenting to the ED. We used demographics, vital signs, and HRV parameters in model building and compared it with the modified early warning score (MEWS), national early warning score (NEWS), and quick sequential organ failure assessment (qSOFA) score.Adult patients clinically suspected to have sepsis in the ED and who met the systemic inflammatory response syndrome (SIRS) criteria were included. Routine triage electrocardiogram segments were used to obtain HRV variables. The primary endpoint was 30-day in-hospital mortality. Multivariate logistic regression was used to derive the SEDS model. MEWS, NEWS, and qSOFA (initial and worst measurements) scores were computed. Receiver operating characteristic (ROC) analysis was used to evaluate their predictive performances.Of the 214 patients included in this study, 40 (18.7%) met the primary endpoint. The SEDS model comprises of 5 components (age, respiratory rate, systolic blood pressure, mean RR interval, and detrended fluctuation analysis α2) and performed with an area under the ROC curve (AUC) of 0.78 (95% confidence interval [CI]: 0.72-0.86), compared with 0.65 (95% CI: 0.56-0.74), 0.70 (95% CI: 0.61-0.79), 0.70 (95% CI: 0.62-0.79), 0.56 (95% CI: 0.46-0.66) by qSOFA (initial), qSOFA (worst), NEWS, and MEWS, respectively.HRV analysis is a useful component in mortality risk prediction for septic patients presenting to the ED.

Prognostic importance of electrocardiographic abnormalities in patients with acute noncardiac conditions

The electrocardiogram's (ECG) ability to aid in the diagnosis and risk stratification of patients with acute coronary syndromes is well established. We sought to investigate the prognostic significance of ECG abnormalities in patients with noncardiac conditions in the emergency department. Patients presenting to the emergency department who were evaluated for possible acute coronary syndrome were consecutively enrolled and an initial ECG was obtained (n = 1024). Only patients with noncardiac diagnoses were reviewed in this analysis (n=493) and 30-month follow-up was obtained. Sinus tachycardia, atrial fibrillation/flutter, ST depression, and left bundle branch block were associated with increased 30-month mortality. After controlling for history of coronary artery disease, age, sex, diabetes mellitus, hypertension, and renal insufficiency, sinus tachycardia and ST-segment depression ≥1 mm were independent predictors of 30-month mortality with a hazard ratio of 2.33 (95% confidence interval, 1.36-4.00; P = 0.002) and 2.49 (95% confidence interval, 1.10-5.67; P = 0.029), respectively. In conclusion, ST-segment depression and sinus tachycardia in patients presenting to the hospital with noncardiac conditions are independently associated with increased 30-month mortality.

The electrocardiogram as a prognostic tool for predicting major cardiac events

Among patients with cardiac disease, the identification of those who are at low risk and those who are at high risk for major cardiac events is crucial for a rational clinical management of individual patients. A correct noninvasive risk stratification of cardiac patients, in particular, has relevant clinical implications because it would avoid unnecessary exposure to potentially risky invasive diagnostic or interventional procedures in low-risk patients, whereas it would allow an appropriate aggressive diagnostic and therapeutic approach in high-risk patients. Furthermore, the appropriate identification of low- and high-risk patients would also have social and economic implications by favoring optimization of resource distribution and costs. A large number of studies in previous decades provided evidence that several methods and variables derived from the analysis of the electrocardiogram (ECG) are powerful predictors of major cardiac events in several clinical conditions. Despite that, there has been limited attention about how several of these findings can be used in clinical practice. Furthermore, in recent years, most studies about risk stratification of cardiac patients have mainly been focused on the use of a number of serum/plasma biomarkers with reduced attention to ECG variables. Surprisingly, however, there have been few attempts to establish whether the various proposed risk markers add any significant information to that obtainable from ECG methods. In this article, the evidence for the prognostic value of variables derived from the assessment of the ECG signal by several methods and techniques will be briefly reviewed. Because of the largeness of the topic, this review will be necessarily incomplete. Because most of the clinical research in this field concerned risk stratification of patients with coronary artery disease, the article will be largely focused on this population of patients. The role of ECG methods in specific cardiac diseases and, in particular, in the general population of asymptomatic subjects will be briefly discussed when believed appropriate and helpful. Furthermore, only major clinical events (ie, cardiac death, arrhythmic events, acute myocardial infarction) will be taken into account as end points in this article. Minor clinical events (eg, coronary revascularization procedures, coronary artery restenosis, recurrences of symptoms) are indeed less robust as end points because they are widely biased by subjective judgments.

Relation of heart rate variability to serum levels of C-reactive protein in patients with unstable angina pectoris

Heart rate variability (HRV) and systemic markers of inflammation have prognostic value in patients with unstable angina pectoris (UAP). However, it is unknown whether any relation exists between HRV parameters and indexes of inflammation in this clinical context. We assessed HRV on 24-hour electrocardiographic Holter recordings, performed within 24 hours of admission, and measured C-reactive protein (CRP) serum levels by a high-sensitivity assay on admission, in 531 patients with UAP (65+/-10 years of age; 347 men) who were enrolled in the prospective multicenter study Stratificazione Prognostica dell'Angina Instabile (SPAI). A significant inverse correlation was found between CRP levels and all HRV parameters, with the highest r coefficient shown with SD of all RR intervals (r= -0.23; p<0.001) in the time domain and with very low-frequency amplitude (r= -0.22; p<0.001) in the frequency domain. When patients were categorized into 4 groups according to CRP quartile levels, statistically significant lower HRV values were observed in the upper CRP quartile. On separate multiple regression analyses, including the most important clinical and laboratory variables, SD of all RR intervals and very low-frequency amplitude were the most significant predictors of increasing CRP levels (p<0.001 for the 2 comparisons). In contrast, in models with SD of all RR intervals and very low-frequency amplitude as dependent variables, CRP was a strong predictor of impaired cardiac autonomic function (p<0.001 for the 2 comparisons). Thus, our data show that, in patients with UAP, high levels of serum CRP levels are significantly associated with decreased HRV, suggesting a possible pathophysiologic link between cardiac autonomic dysfunction and inflammatory activity.

Prognostic value of ventricular arrhythmias and heart rate variability in patients with unstable angina

OBJECTIVES

To assess the prognostic value of ventricular arrhythmias (VA) and heart rate variability (HRV) in patients with unstable angina.

DESIGN

Multicentre prospective study.

SETTING

17 cardiological centres in Italy.

PATIENTS

543 consecutive patients with unstable angina and preserved left ventricular function (ejection fraction >or=40%) enrolled in the SPAI (Stratificazione Prognostica dell'Angina Instabile) study.

METHODS

Patients underwent 24 h ECG Holter monitoring within 24 h of hospital admission. Tested variables were frequent ventricular extrasystoles (>or=10/h), complex (that is, frequent or repetitive) VA, and bottom quartile values of time-domain and frequency-domain HRV variables. Primary end points were in-hospital and six-month total and cardiac deaths.

RESULTS

Eight patients died in hospital (1.5%) and 32 (5.9%, 29 cardiac) during follow up. Both complex VA and frequent extrasystoles were strongly predictive of death in hospital and at follow up, even after adjustment for clinical (age, sex, cardiac risk factors and history of myocardial infarction) and laboratory (troponin I, C reactive protein and transient myocardial ischaemia on Holter monitoring) variables. At univariate analysis bottom quartile values of three HRV variables (standard deviation of RR intervals index, low-frequency amplitude and low to high frequency ratio) were associated with in-hospital death, and bottom quartile values of most HRV variables predicted six-month fatal events. At multivariate Cox survival analysis reduced low-frequency amplitude was consistently found to be independently associated with fatal end points.

CONCLUSION

In patients with unstable angina with preserved myocardial function, both VA and HRV are independent predictors of in-hospital and medium-term mortality, suggesting that these factors should be taken into account in the risk stratification of these patients.

FRISC score for selection of patients for an early invasive treatment strategy in unstable coronary artery disease

OBJECTIVE

To develop a scoring system for risk stratification and evaluation of the effect of an early invasive strategy for treatment of unstable coronary artery disease (CAD).

DESIGN

Retrospective analysis of a randomised study (FRISC II; fast revascularisation in instability in coronary disease).

SETTING

58 Scandinavian hospitals.

PATIENTS

2457 patients with unstable CAD from the FRISC II study.

MAIN OUTCOME MEASURES

One year rates of mortality and death/myocardial infarction (MI).

METHODS

Patients were randomly assigned to an early invasive or a non-invasive strategy. From the non-invasive cohort independent variables of death or death/MI were identified.

RESULTS

Seven factors, age > 70 years, male sex, diabetes, previous MI, ST depression, and increased concentrations of troponins and markers of inflammation (interleukin 6 or C reactive protein), were associated with an independent increased risk for death or death/MI. In patients with > or = 5 of these factors the invasive strategy reduced mortality from 15.4% (20 of 130) to 5.2% (7 of 134) (risk ratio (RR) 0.34, 95% confidence interval (CI) 0.15 to 0.78, p = 0.006). Death/MI was also reduced in patients with 3-4 factors from 15.7% (80 of 511) to 10.8% (58 of 538) (RR 0.69, 95% CI 0.50 to 0.94, p = 0.02). Neither death nor death/MI was reduced in patients with 0-2 risk factors.

CONCLUSION

In unstable CAD, this scoring system based on factors independently associated with an adverse outcome can be used shortly after admission to the hospital for risk stratification and for selection of patients to an early invasive treatment strategy.

Risk stratification in acute coronary syndrome: focus on unstable angina/non-ST segment elevation myocardial infarction

Although there have been advances in the management of unstable angina/non-ST segment elevation myocardial infarction syndromes, the rate of cardiovascular mortality after discharge is still unacceptably high. With many therapeutic options available, the clinician is challenged to identify the safest and most effective treatment for long term survival of each individual patient

Heart rate variability estimates of autonomic tone: relationship to mapping pathological and procedural stress responses in coronary disease

Many lines of experimental evidence suggest the interplay of the autonomic nervous system and a variety of mediators of vascular atheroma and ultimately vascular occlusion. In vivo study in human volunteers and patients is hampered by the lack of a reliable and sensitive marker of prevailing autonomic tone able to reflect the appropriate dynamic change in nervous activity. Currently, the modern standard for definition of autonomic tone is based on a variety of analyses of R-R interval variability from the surface ECG. In this review, we consider whether heart rate variability techniques are sensitive enough to define relevant clinical interactions between neural tone and other mediators of vascular occlusion--specifically, mechanical pressure, thrombotic and hormonal factors--which are relevant to atherosclerotic vascular disease.