Chest pain assessment on the fast track

Chest pain assessment on the fast track – In House

Two new approaches to evaluating chest pain have been introduced that achieve a “collapse in the time required to evaluate a patient with possible ACS [acute coronary syndrome],” according to authors of an editorial recently published with the two studies in Annals of Emergency Medicine.

The Erlanger Chest Pain Evaluation Protocol, explain Fesmire et al, comprises six incremental steps (see Table 1). The protocol was tested in a one-year study of 2,074 consecutive patients who presented with chest pain to the Erlanger Medical Center emergency department (ED), Chattanooga, Tennessee. According to physician judgment and clinical findings, patients either underwent emergency reperfusion therapy, were admitted for ACS, underwent nuclear stress testing for possible ACS, or were admitted or discharged with a non-ACS condition.

The protocol was judged effective in confirming or ruling out acute myocardial infarction (AMI, the discharge diagnosis for 8.6% of patients; recent AMI was found in 1.3%) and 30-day ACS (reported in 15.8% and defined as MI, percutaneous coronary intervention or coronary artery bypass grafting, detection of at least 70% stenosis of a major coronary artery, a life-threatening complication, or cardiac death within 30 days’ follow-up).

In the same issue, Baxt and colleagues describe their development of an artificial neural network in which 40 variables (including patient history, physical examination, ECG findings, and levels of chemical markers) are input; computer analysis is then used to distinguish between cardiac and noncardiac chest pain. In a “jackknife” study, a group of 2,204 previously evaluated patients was divided, with baseline data from half used to train the network and from the other half to test it; the process was then reversed and information pooled.

Through the network, 128 cases of MI were diagnosed (81.1% confirmed by coronary artery catheterization), as were 199 cases of unstable angina (57.7% confirmed) and 34 cases of angina, leaving 1,843 diagnoses of noncardiac chest pain. Although some 5% of all required data were missing, the artificial neural network was more effective than three other statistical approaches.

Editorialists Andra L. Blomkalns, MD, and W. Brian Gibler, MD, praise the system created by Baxt and associates because “through artificial intelligence, [it] improves its diagnostic capabilities after every new patient evaluation.” The Erlanger protocol, they also note, is widely generalizable because it includes high-and low-risk patients, and it focuses on net increases in serial cardiac marker levels rather than rigid cutoff points.

The scarcity of hospital beds, note Drs. Blomkalns and Gibler, makes ruling out ACS in the ED—and complying with guidelines for management of confirmed ACS–increasingly important.

Fesmire FM, Hughes AD, Fody EP, et al. The Erlanger Chest Pain Evaluation Protocol: a one-year experience with serial 12-lead ECG monitoring, two-hour delta serum marker measurements, and selective nuclear stress testing to identify and exclude acute coronary syndromes. Ann Emerg Med. 2002;40:584-594.

Baxt WG, Shofer ES, Sites ED, Hollander JE. A neural network aid for the early diagnosis of cardiac ischemia in patients presenling to the emergency department with chest pain. Ann Emerg Med. 2002;40:575-583.

Blomkalns AL, Gibler WB. It’s about time: the evolution of acute coronary syndrome evaluation in the emergency department [editoriall. Ann Emerg Med. 2002;40:595-597.

Table 1

THE ERLANGER CHEST PAIN EVALUATION PROTOCOL

A positive result in one or more of the following steps is considered a positive protocol:

* Initial ECG reflecting acute or reciprocal injury

* Baseline CK-MB level [greater than or equal to] 10 ng/mL and index of [greater than or equal to] 5% or cTnI level [greater than or equal to] 2 ng/mL

* Serial 12-lead ECG monitoring indicating new or evolving injury or ischemia

* Minimum 1.5-ng/mL increase in CK-MB level or minimum 0.2-ng/mL increase in cTnI level in 2 h

* Clinical diagnosis of ACS (despite a negative evaluation at 2 h)

* Reversible perfusion defect on nuclear stress scan vs resting scan

ECG, electrocardiogram; CK-MB, creatine kinase MB band; cTnI, cardiac troponin I; ACS, acute coronary syndrome.

Source: Fesmire et al. Ann Emerg Med. 2002;40:584-594.

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