MDCT in Early Triage of Patients With Acute Chest Pain
MDCT in Early Triage of Patients With Acute Chest Pain
Objective: Current risk stratification of patients with acute chest pain but normal initial cardiac enzymes and nondiagnostic ECG is inefficient. We sought to determine whether contrast-enhanced MDCT-based detection of stenosis is feasible and improves early and accurate triage of patients with acute chest pain.
Subjects and Methods: We studied 40 patients (53% men; mean age, 57 ± 13 years) with chest pain who were awaiting hospital admission to rule out an acute coronary syndrome (ACS) despite the absence of diagnostic ECG changes and normal cardiac enzymes on emergency department presentation. Patients underwent contrast-enhanced MDCT before hospital admission. Afterward, patients received standard clinical care. All physicians involved in the patients' care were blinded to the results of MDCT. An expert panel established the presence or absence of ACS based on American Heart Association (AHA) guidelines. The MDCT images were evaluated for the presence of significant coronary artery stenosis (diameter reduction > 50%) and were used to make a triage decision.
Results: All five patients (12.5%) with ACS (one with non-ST elevation myocardial infarction, four with unstable angina pectoris) had at least one significant coronary stenosis on MDCT (sensitivity, 100% [95% CI, 49-100%)]. ACS was ruled out in 35 patients (87.5%). Significant coronary stenosis was excluded in 26 of the 35 patients without ACS by MDCT (specificity, 74% [CI, 75-88%]), potentially saving 70% of unnecessary hospital admissions.
Conclusion: MDCT-based detection of significant coronary stenoses has tremendous potential to decrease the number of unnecessary hospital admissions, without reducing appropriate admission rates, in patients with chest pain who have nondiagnostic ECG results and normal cardiac enzymes. These results are likely to further improve with advances in MDCT technology.
More than 5 million patients with acute chest pain present to emergency departments in the United States each year. Early triage of these patients is important both for prognosis and treatment but it remains difficult. Patients at highest risk for adverse outcomes derive the greatest benefit from glycoprotein IIb/IIIa inhibitor therapy and early revascularization. By contrast, patients at low risk may be discharged without long-term impact on their risk of death or myocardial infarction and can safely be assessed further as outpatients.
Unfortunately, triage decisions guided by an estimate of patient risk for acute coronary syndrome (ACS) using a variety of clinical predictors is often ineffective, especially in patients with convincing clinical presentation but normal initial cardiac enzymes and normal or nondiagnostic ECG. The predictive value of single variables such as patient age, sex, presence of risk factors, and biochemical markers for adverse outcomes is limited. Moreover, the rate of missed ACS remains unacceptably high (2%) and is associated with a twofold increased risk of mortality, contributing to the low threshold of emergency department physicians to admit patients with chest pain. Because of the limited ability to correctly risk stratify patients with acute chest pain, the potentially fatal consequences of missed ACS, and the resulting liability issues (20% of emergency department malpractice dollar losses), more than 2 million patients with acute chest pain are admitted to the hospital without developing an ACS. Because 60% of patients eligible for early emergency department discharge are actually admitted to the hospital, the number of potentially unnecessary hospital days (per 100 patients enrolled) is high, ranging from 65 in New Zealand to 839 in Germany.
The ability to quickly and accurately exclude a potentially life-threatening coronary cause of chest pain would improve patient care and potentially reduce health care costs significantly.
MDCT systems with submillimeter spatial and high temporal resolutions that permit motion-free imaging of the coronary arteries are becoming available in many emergency departments around the United States. A growing number of studies provide sufficient evidence that MDCT is highly accurate for detecting significant coronary stenoses (> 50% luminal narrowing) in the major epicardial coronary arteries compared with invasive selective coronary angiography. Recent data indicate the feasibility of 64-MDCT to detect stenosis in smaller side branches with a sensitivity of 78-100%, specificity of 96-100%, positive predictive value of 87-100%, and negative predictive value of 97-100%.
Noninvasive assessment of coronary artery disease is not part of the standard clinical care of patients with acute chest pain. Conceivably, implementation of noninvasive coronary imaging in the emergency department could influence existing paradigms for triage and care of patients with acute chest pain by significantly reducing the number of unnecessary hospital admissions.
The aim of this pilot study was to determine the accuracy of the noninvasive detection of significant coronary artery stenosis by MDCT, and to ascertain the feasibility of using the findings for triage decision making in patients with acute chest pain who are awaiting hospital admission despite normal initial cardiac enzymes and normal or nondiagnostic ECG on emergency department presentation.
Abstract and Introduction
Abstract
Objective: Current risk stratification of patients with acute chest pain but normal initial cardiac enzymes and nondiagnostic ECG is inefficient. We sought to determine whether contrast-enhanced MDCT-based detection of stenosis is feasible and improves early and accurate triage of patients with acute chest pain.
Subjects and Methods: We studied 40 patients (53% men; mean age, 57 ± 13 years) with chest pain who were awaiting hospital admission to rule out an acute coronary syndrome (ACS) despite the absence of diagnostic ECG changes and normal cardiac enzymes on emergency department presentation. Patients underwent contrast-enhanced MDCT before hospital admission. Afterward, patients received standard clinical care. All physicians involved in the patients' care were blinded to the results of MDCT. An expert panel established the presence or absence of ACS based on American Heart Association (AHA) guidelines. The MDCT images were evaluated for the presence of significant coronary artery stenosis (diameter reduction > 50%) and were used to make a triage decision.
Results: All five patients (12.5%) with ACS (one with non-ST elevation myocardial infarction, four with unstable angina pectoris) had at least one significant coronary stenosis on MDCT (sensitivity, 100% [95% CI, 49-100%)]. ACS was ruled out in 35 patients (87.5%). Significant coronary stenosis was excluded in 26 of the 35 patients without ACS by MDCT (specificity, 74% [CI, 75-88%]), potentially saving 70% of unnecessary hospital admissions.
Conclusion: MDCT-based detection of significant coronary stenoses has tremendous potential to decrease the number of unnecessary hospital admissions, without reducing appropriate admission rates, in patients with chest pain who have nondiagnostic ECG results and normal cardiac enzymes. These results are likely to further improve with advances in MDCT technology.
Introduction
More than 5 million patients with acute chest pain present to emergency departments in the United States each year. Early triage of these patients is important both for prognosis and treatment but it remains difficult. Patients at highest risk for adverse outcomes derive the greatest benefit from glycoprotein IIb/IIIa inhibitor therapy and early revascularization. By contrast, patients at low risk may be discharged without long-term impact on their risk of death or myocardial infarction and can safely be assessed further as outpatients.
Unfortunately, triage decisions guided by an estimate of patient risk for acute coronary syndrome (ACS) using a variety of clinical predictors is often ineffective, especially in patients with convincing clinical presentation but normal initial cardiac enzymes and normal or nondiagnostic ECG. The predictive value of single variables such as patient age, sex, presence of risk factors, and biochemical markers for adverse outcomes is limited. Moreover, the rate of missed ACS remains unacceptably high (2%) and is associated with a twofold increased risk of mortality, contributing to the low threshold of emergency department physicians to admit patients with chest pain. Because of the limited ability to correctly risk stratify patients with acute chest pain, the potentially fatal consequences of missed ACS, and the resulting liability issues (20% of emergency department malpractice dollar losses), more than 2 million patients with acute chest pain are admitted to the hospital without developing an ACS. Because 60% of patients eligible for early emergency department discharge are actually admitted to the hospital, the number of potentially unnecessary hospital days (per 100 patients enrolled) is high, ranging from 65 in New Zealand to 839 in Germany.
The ability to quickly and accurately exclude a potentially life-threatening coronary cause of chest pain would improve patient care and potentially reduce health care costs significantly.
MDCT systems with submillimeter spatial and high temporal resolutions that permit motion-free imaging of the coronary arteries are becoming available in many emergency departments around the United States. A growing number of studies provide sufficient evidence that MDCT is highly accurate for detecting significant coronary stenoses (> 50% luminal narrowing) in the major epicardial coronary arteries compared with invasive selective coronary angiography. Recent data indicate the feasibility of 64-MDCT to detect stenosis in smaller side branches with a sensitivity of 78-100%, specificity of 96-100%, positive predictive value of 87-100%, and negative predictive value of 97-100%.
Noninvasive assessment of coronary artery disease is not part of the standard clinical care of patients with acute chest pain. Conceivably, implementation of noninvasive coronary imaging in the emergency department could influence existing paradigms for triage and care of patients with acute chest pain by significantly reducing the number of unnecessary hospital admissions.
The aim of this pilot study was to determine the accuracy of the noninvasive detection of significant coronary artery stenosis by MDCT, and to ascertain the feasibility of using the findings for triage decision making in patients with acute chest pain who are awaiting hospital admission despite normal initial cardiac enzymes and normal or nondiagnostic ECG on emergency department presentation.
