Evaluation and risk stratification of patients with chest pain in the emergency department. Predictors of life-threatening events

The risk for acute coronary syndrome associated with atrial fibrillation among ED patients with chest pain syndromes

OBJECTIVE

We sought to determine if atrial fibrillation is associated with an increased risk for an acute coronary syndrome (ACS) among emergency department (ED) patients with chest pain syndromes.

METHODS

We performed a retrospective analysis of a prospectively collected database on ED patients with chest pain by selecting patients with atrial fibrillation and frequency-matched control subjects without atrial fibrillation. Measured outcomes were acute myocardial infarction (AMI), ACS, and unstable angina (UA). The relative risks of AMI, ACS, and UA associated with atrial fibrillation were calculated.

RESULTS

One hundred forty patients with atrial fibrillation and 683 matched control subjects were identified. The rates of AMI for the atrial fibrillation and control groups were 11.4% and 10.8%, respectively; those of ACS were 27.9% and 26.7%, respectively; and those of UA were 16.4% and 15.8%, respectively. The relative risks of AMI and ACS did not increase in patients with atrial fibrillation: AMI, 1.05 (95% confidence interval [CI] = 0.63-1.75); ACS, 1.05 (95% CI = 0.78-1.40); and UA, 1.05 (95% CI = 0.6-1.7).

CONCLUSION

Among patients presenting to the ED with chest pain syndromes, atrial fibrillation is not associated with an increased risk for AMI, ACS, and UA.

Modified Thrombolysis in Myocardial Infarction (TIMI) risk score to risk stratify patients in the emergency department with possible acute coronary syndrome

OBJECTIVE

To assess the prognostic utility of the Thrombolysis in Myocardial Infarction (TIMI) risk score in patients in the emergency department (ED) evaluated for possible acute coronary syndrome (ACS).

BACKGROUND

The ability of the TIMI risk score to risk stratify patients at initial presentation in the ED with chest pain of unclear etiology is uncertain.

METHODS

We investigated the prognostic utility of the TIMI risk score in 947 consecutive patients evaluated in the ED for possible ACS. A multivariate analysis was done to evaluate the independent predictive power of the individual components of the TIMI risk score to predict an adverse event at 30 days (all-cause death, myocardial infarction, and coronary revascularization).

RESULTS

There were 151 (16%) patients diagnosed with ACS. At 30 days there were 48 (5%) deaths, 84 (9%) myocardial infarctions, and 49 (5%) coronary revascularization procedures. The mean TIMI risk score was significantly higher in patients with an adverse event compared with those without (2.6 +/- 1.3 vs. 1.7 +/- 1.2, P < 0.0001). Four of the 7 TIMI risk factors (age > or = 65 years, ST segment deviation > or = 0.5 mm elevated troponin I, and coronary stenosis > or = 50%) were independently associated with adverse events. A simplified TIMI risk score was computed and was found to have similar prognostic ability as the 7 variable TIMI risk score.

CONCLUSION

A modified TIMI risk score may simplify risk stratification of ED patients with undifferentiated chest pain.

Prevalence of esophageal disorders in patients with recurrent chest pain

The objective of this study is to determine the prevalence of esophageal disorders (ED) associated with recurrent chest pain (RCP) and the utility of esophageal functional tests (EFT) in the study of these patients. The cross-sectional study was conducted at Hospital Clínico de La Frontera, Chile. One hundred and twenty-three patients with RCP were studied using esophageal manometry, edrophonium stimulation and 24-h pH monitoring. The performance of EFT was considered acceptable when they were capable of finding ED. To state the probability that RCP had an esophageal origin, patients were classified according to whether their pain had a probable, possible or unlikely esophageal origin. The prevalence of ED was determined according to diagnoses obtained after applying EFT and a multivariate analysis was performed to examine the association between the esophageal origin of RCP and ED. Rates of correct diagnosis of 65.9%, 56.9% and 31.7% was verified for 24-h pH monitoring, esophageal manometry and edrophonium stimulation, respectively. In 38.2% of patients with RCP, the pain was probably of esophageal origin, in 42.3% there was a possible esophageal origin and in 19.5% an unlikely esophageal origin. A 44.7% prevalence of GERD, 26.8% of GERD with secondary esophageal motor dysfunction and 8.9% of pure esophageal motor dysfunction were verified. The multivariate analysis allowed us to verify the association between the probability of esophageal origin of RCP, the variables RCP duration, esophagitis and dysphagia coexistence (P= 0.037, P= 0.030 and P= 0.024, respectively), and a statistically significant association between ED and dysphagia coexistence (P= 0.028). A high prevalence of ED was identified in patients with RCP.

Chest pain in athletes

The symptom of chest pain in the athlete can represent anything from a nonspecific musculoskeletal strain to a life-threatening condition such as tension pneumothorax. For the physician charged with evaluating this patient population, a thorough knowledge of the possible etiologies, their usual diagnostic algorithms, available imaging modalities, and potential therapeutic options is essential. Although the vast majority of patients with traumatic chest pain will not harbor significant pathology, the clinician must be prepared for those few who do have such conditions, and be prepared to intervene in an appropriate, time-sensitive fashion.

It is safe to manage selected patients with acute coronary syndromes in unmonitored beds

This prospective, observational study evaluated the safety of the Western Hospital admission protocol for patients with suspected acute coronary syndromes. The study included all patients admitted from the Emergency Department with an admission diagnosis of unstable angina, post infarct angina, atypical chest pain, or chest pain for evaluation. Data collected included demographic data, admission diagnosis, location of admission (bed with or without cardiac monitoring), past medical history and presenting chest pain history to determine Agency for Health Care Policy (AHCPR) and Western Hospital (WH) protocol classifications, cardiac enzyme assays, electrocardiogram analysis, adverse outcomes [death, myocardial infarction (MI), dysrhythmia, acute pulmonary edema, recurrent pain], diagnosis at hospital discharge, and length of stay-(LOS). There were 508 patients with a mean age of 63.7 years enrolled in the study. Three hundred nineteen (62.8%) were admitted to beds without any cardiac monitoring. There was one unexpected death in the unmonitored group, an 85 year-old patient who suffered a presumed dysrhythmia and whom the treating physician had decided was not for resuscitation. Twelve patients suffered nonfatal MI, and none suffered pulmonary edema. All MI patients made an uneventful recovery, and none required thrombolysis. If all patients had been admitted to an area of care based on AHCPR guidelines, an additional 310 admissions to monitored beds would have been required. The results of this study suggest that selected patients with suspected acute coronary syndromes can be safely managed in beds without continuous cardiac monitoring.

Advances create opportunities: implementing the major tenets of the new unstable angina guidelines in the emergency department

Of all the clinical syndromes with which emergency physicians must deal, chest pain of coronary cause has benefited from the most striking recent advances both in diagnostic approach (cognitive and technologic) and in therapeutic options. Chest pain evaluation and management have become important foci of research in emergency medicine, and entire units are dedicated to its clinical prosecution in emergency departments and elsewhere in the hospital. New diagnostic tools are proposed and studied on a regular basis. Antiplatelet, antithrombin, and fibrinolytic agents unknown in clinical practice as recently as 5 years ago have secured places in the emergency physician's armamentarium for treating acute coronary syndrome. Many of these diagnostic and therapeutic tools have been developed in the coronary care unit and in the cardiac catheterization laboratory. Although intuitively they may also be useful outside of those settings, they have unreliably been brought to the ED for implementation and resultant appropriate prompt and early care of the coronary patient who does not meet fibrinolytic criteria. As emergency physicians seek to bring accurate chest pain risk stratification into their practice and begin to use new therapeutic agents to minimize myocardial damage before turning the patient's care over to other specialists, it is essential that they are familiar with the data supporting these approaches. In this commentary, we seek to place the American College of Cardiology/American Heart Association unstable angina guidelines into the clinical context of the ED.

A prediction model for prehospital triage of patients with suspected cardiac ischemia

The American College of Cardiology recommends that patients with high risk acute myocardial infarction (AMI) be triaged to hospitals with percutaneous transluminal coronary angioplasty capability. However, there are no prehospital triage criteria to select candidates for bypassing community hospitals and being taken directly to "cardiac centers." This article assesses which independent variables predict death within 7 days in patients with suspected AMI transported by EMS. This is a retrospective study of 291 AMI patients transported by ambulance to 3 hospitals during 1996-1997. Included were patients who were (n = 244) > or =18 years of age, had a ED chief complaint of chest pain or dyspnea for whom we had mortality data. Mortality at 7 days, our primary outcome measure, was obtained by using a metropolitan Detroit tricounty death index records. Differences between the survivors and nonsurvivors were assessed using the Student's t-test and chi-square tests. Multiple triage criteria were assessed for optimal identification of high risk patients by constructing a logistic multivariate model. Among the study population, 15% died within 7 days (95% confidence interval (CI) 10.3-19.2), and this group represented 63.2% of all deaths over a 2 year surveillance period. Survivors, compared to nonsurvivors, were 14.1 years younger (P < or = .001) and more often men (P < or = 0.001). The dispatch time to ED arrival was less among survivors than nonsurvivors (42.8 vs. 50.6 min, P < or = .01). EMS vital signs differed by survivor status. Among survivors, HR was lower (-11.9 bpm; P < or = 0.01), RR was lower (-6.7 rpm; P < or = .001), SBP was higher (+14.5 mmHg; P < or = 0.05) and DBP was higher (+13.2 mm Hg; P < or = .01). A multivariate model identified the following as independent predictors of early mortality: female gender (OR = 2.3; P < or = .05), age > or =65 (OR = 5.9; P < or = .01), RR > or = 20 (OR = 4.6; P < or = .001), SBP < 120 (OR = 2.4; P < or = .05). The overall model was 86% sensitive and 53% specific with an area under the receiving operating characteristic curve of 0.8 (P < or = .001). A triage rule based on a multivariate model can identify the group at high risk of early cardiac death. This decision rule needs to be prospectively validated.

ECG scores for a triage of patients with acute myocardial infarction transported by the emergency medical system

Prehospital triage of cardiac patients for bypass from community hospitals to cardiac centers may improve survival. This article determines if electrocardiogram (ECG)-based scoring triage methods (Aldrich MI scoring, QRS distortion, and the TIMI classification) and location of infarct (via 12 lead ECG) are associated with mortality before and after adjusting for age, sex, and race. It is a retrospective study of 291 AMI adult patients transported by ambulance to community hospitals or cardiac centers. Patients with an ED chief complaint of chest pain or dyspnea, presence of MI as defined by ECG findings of 0.1 mV of ST segment elevation in two leads or positive CPK-MB were eligible for the study. The primary outcome variable was 2-year mortality as determined with a metropolitan Detroit tri-county death index. Logistic regression was used to calculate the unadjusted and adjusted odds ratios (with 95% CIs) of the predictor variables with mortality. Of the initial population selected for the study (n = 291), 229 patients were eligible for the analysis. The mean age was 66 years (SD of 14.4) with 63.8% being male and 54% being white. The overall mortality point estimate was 21.3% (95% CI of 15.2 to 27.3%). Aldrich scores and QRS distortion (yes/no) were not associated with mortality. Patients classified as a "high risk" for AMI per TIMI status were almost 3 times more likely to die than those at "low risk" and reached borderline statistical significance (P = .06) after adjusting for the covariates. Having an anterior infarct, as opposed to an inferior infarct, was significantly associated with death before and after adjusting for the covariates (Unadjusted OR = 2.6, Adjusted OR = 2.8). Properly training emergency medical system professionals in this area may prove useful for identifying higher risk AMI patients in the prehospital setting.

Identification of chest pain patients appropriate for an emergency department observation unit

There are no perfect tests or algorithms to exclude ACI. Because acute coronary occlusion often occurs in patients with low-grade coronary stenosis, the diagnostic goal of a chest pain diagnostic protocol is not to identify patients with CAD, but rather to identify patients who may be safely discharged home without the development of complications such as MI, unstable angina, death, shock, or CHF over the next 1 to 6 months. There is an advantage to evaluating patients at the time of their symptoms. Patients who have a small plaque that is ruptured, leading to intracoronary thrombosis and ischemia, will manifest ischemia on diagnostic testing that could missed in routine outpatient testing when their plaque were stable. The diagnosis and risk stratification of acute coronary ischemia in the ED depends on a careful history and interpretation of the ECG. Multiple regression models using readily available data (e.g., history, physical examination, and ECG) provide the best tools for risk stratification. If one is deciding how to select patients for an EDOU chest pain evaluation, diagnostic tools that have previously been tested and validated in this setting are preferable. These include the Multicenter Chest Pain Study derived tools (i.e., Goldman, Lee), the ACI and ACI-TIPI tools, and sestamibi risk stratification tools. This is not to say that other tools may not play a role at individual institutions. It is probably better to select a consistent approach and evaluate its performance, rather than to allow random variation to dictate practice. The future direction probably will involve standardization of the ED chest pain population. This allows outcome and cost-effectiveness comparative research of various strategies for patients with normal or nondiagnostic ECGs and normal biomarkers. Although this approach allows more precise stratification, the risk will never be zero, meaning that there will never be a substitute for good clinical judgment and close follow-up care.

Stress testing for risk stratification of patients with low to moderate probability of acute cardiac ischemia

In summary, this article focused on the use of stress testing to risk-stratify patients at the conclusion of their emergency evaluation for ACI. As discussed, those patients in the probably not ACI category require additional risk stratification prior to discharge. It should be kept in mind that patients in this category are heterogeneous, containing subgroups at both higher and lower risk of ACI and cardiac events. The patients with lower pretest probability for ACI may only need exercise testing in the ED. Patients with higher pretest probability should undergo myocardial perfusion or echocardiographic stress testing to maximize diagnostic and prognostic information. Prognostic information is the key to provocative testing in the ED. Prognostic information is the component that will help emergency physicians identify the patients who may be discharged home safely without having to worry about a 6% annual cardiac death rate and a 10% overall death rate over the next 30 months. Stress testing provides this key prognostic data, and it can be obtained in short-stay chest pain observation units in a safe, timely, and cost-effective fashion.