754 COMMENTARIES Hsieh et al. • LOW-RISK CHEST PAIN

How ‘‘Low’’ Can We Go: Assessing Risk inChest Pain Patients

What to do with emergencydepartment (ED) patients

complaining of chest pain butwithout an obvious ‘‘bad’’ cause—especially but not limited toacute coronary ischemia—is anongoing dilemma for physicians.Aided by diagnostic tools andclinical guidelines, emergencyphysicians can usually identifypatients at high risk for acutemyocardial infarction (AMI) andacute coronary syndrome (ACS).The more difficult question iswhom we can safely send home.Instinctively, we feel thatyounger patients with ‘‘nonclas-sic’’ histories, no coronary arterydisease risk factors, and a nor-mal electrocardiogram (ECG)will probably do well if dis-charged, because the disease(ACS) is either absent or un-likely to cause harm in the shortterm. The problems are twofold:Limited evidence exists to backup this belief and there is uncer-tainty over how little risk ofdeath or serious harm is ‘‘OK.’’Most clinicians want the latter tobe zero or very near that. Cur-rently, to the best of our knowl-edge, a valid tool does not existto help physicians identify a sub-set of chest pain patients with azero or very near zero likelihoodof adverse cardiovascular out-come if discharged from the ED.Therefore, the clinician mustchoose between two courses—ei-ther admitting many patientswith a low but non-zero risk ofimminent harm or sending themhome with follow-up by the pri-mary care physician. In the ab-sence of alternatives such as anED-based chest pain observationarea with well-defined protocolsand resources (still not commonin U.S. EDs), the choice is clearin most settings: we ‘‘liberally’’admit chest pain patients. Thisovertriage produces an inpatient

population with a low yield of anACS diagnosis (hovering near25–30%) and still manages todischarge 2–5% of ACS patientsfrom the ED.1–3

Two articles in this issue ofAcademic Emergency Medicineattempt to further answer thequestion of which chest pain pa-tients we can send home. Thestudy by Walker et al.4 addressesthe issue of whether younger pa-tients without cardiac history,risk factors, and ECG abnormal-ities are truly at low risk for ad-verse cardiovascular events. Inthe 16-month study period, theauthors prospectively identifiedand followed 487 patients be-tween the ages of 24 and 39years presenting to a universityED with non-cocaine-relatedchest pain. The investigators ex-amined the incidence of ACS insubsets of young adults withoutprior cardiac history and eitherwithout coronary artery diseaserisk factors or with a normalECG. Using either set of criteriaidentified patients with an in-cidence of ACS or importantadverse cardiovascular eventswithin 30 days of ED presenta-tion of 1% or less. This findingconfirms our suspicion thatmany young adult patients withchest pain are at low risk forACS or poor short-term out-comes from ACS. These resultsmay be helpful in the evaluationof young adults but would not beapplicable to the vast majority ofED chest pain patients who areover the age of 40. Furthermore,application of these rules wouldhave either increased or left un-changed the admission ratewithin the study cohort withoutan increase in sensitivity com-pared with physician judgmentalone.

Walker et al.’s study was partof a larger study by Limkakeng

et al.5 to evaluate the strategy ofusing a validated prediction rulein conjunction with a single car-diac troponin I (cTnI) determi-nation to identify a subset ofchest pain patients safe for dis-charge from the ED. The inves-tigators hypothesized that unse-lected adult ED chest painpatients with a 4% or less risk ofAMI or emergent complicationsidentified by a computerized pro-tocol (Goldman et al.1,6) and anormal initial cTnI level (#0.3ng/mL) would have a 1% or lessrisk of a poor outcome and there-fore be safe for discharge fromthe ED. Instead they found that4.9% of the 998 prospectivelyidentified patients who fulfilledboth criteria experienced an ad-verse outcome during the 30-dayfollow-up period, with 10 deaths,23 AMIs, and 23 revasculariza-tion procedures. Four of thesepatients were discharged fromthe ED.

The inability of Limkakeng etal. to identify a truly low-risk pa-tient subset is perhaps not sur-prising. Neither the Goldmanprediction rule nor the use ofinitial cTnI values has been in-dividually shown to exclude ACSor its attendant complications.The purpose of the Goldmancomputer protocol was to deter-mine whether some chest painpatients could be safely moni-tored in a less-intensive, non-in-tensive-care-unit inpatient set-ting1,6 rather than whether somepatients could be safely dis-charged from the ED, two ques-tions with very different implica-tions for emergency physicians.While the algorithm can identifypatients at high risk for AMI orits complications while reducingcoronary care unit admissions, itis inappropriate for use as a toolto identify low-risk patients forED discharge. Similarly, while el-evated cTnI levels on serial mea-surements are highly specific formyocardial injury, 15–59% of pa-tients with abnormal serial cTnIresults or who were diagnosed

ACADEMIC EMERGENCY MEDICINE • July 2001, Volume 8, Number 7 755

with ACS had normal cTnI levelson their initial presentations tothe ED.7–11 The results of theLimkakeng study suggest thatcombining two imperfect strate-gies does not produce an im-proved one.

So the search for an evidence-based prediction rule that can ac-curately identify adult chest painpatients at very low risk for ACSand reduce unnecessary hospitaladmissions continues. The futuremay lie in rules that incorporaterisk assessment based on newtechnologies such as nuclear im-aging rather than refinement ofpast strategies.12 Meanwhile,‘‘chest pain, possible MI’’ remainsa common admission diagnosis,and emergency physicians mustcontinue to live with the concernof sending home a chest pain pa-tient with ACS.—MARGARETHSIEH MD (hsiehm@msx.upmc.edu), THOMAS E. AUBLE, PhD,and DONALD M. YEALY, MD, De-partment of Emergency Medicine,

University of Pittsburgh, Pitts-burgh, PA

Key words. chest pain; acute coro-nary syndrome; risk stratification.

References

1. Goldman L, Weinberg M, Weisberg M,et al. A computer-derived protocol to aidin the diagnosis of emergency room pa-tients with acute chest pain. N Engl JMed. 1982; 307:588–96.2. Lee TH, Cook EF, Weisberg M, et al.Acute chest pain in the emergency room.Identification and examination of low-risk patients. Arch Intern Med. 1985;145:65–9.3. Hutter AM, Amsterdam EA, Jaffe AS.Task force 2: acute coronary syndrome:section 2B—chest discomfort evaluationin the hospital. J Am Coll Cardiol. 2000;35:825–80.4. Walker NJ, Sites FD, Shofer FS, Hol-lander JE. Characteristics and outcomesof young adults who present to the emer-gency department with chest pain. AcadEmerg Med. 2001; 8:703–8.5. Limkakeng A Jr, Gibler WB, PollackC, et al. Combination of Goldman riskand initial cardiac troponin I for emer-gency department chest pain patient riskstratification. Acad Emerg Med. 2001; 8:696–702.6. Goldman L, Cook EF, Brand DA, et

al. A computer protocol to predict myo-cardial infarction in emergency depart-ment patients with chest pain. N Engl JMed. 1988; 318:797–803.7. Antman EM, Tanasijevic MJ, Thomp-son B, et al. Cardiac-specific troponin Ilevels to predict the risk of mortality inpatients with acute coronary syndrome.N Engl J Med. 1996; 335:1342–9.8. Hamm CW, Goldmann BU, HeeschenC, Kreymann G, Berger J, Meinertz T.Emergency room triage of patients withacute chest pain by means of rapid test-ing for cardiac troponin T or troponin I.N Engl J Med. 1997; 337:1648–53.9. Tucker JF, Collins RA, Anderson AJ,Hauser J, Kalas J, Apple FS. Early di-agnostic efficiency of cardiac troponin Iand troponin T for acute myocardial in-farction. Acad Emerg Med. 1997; 4:13–21.10. Green GB, Li DJ, Bessman ES, CoxJL, Kelen GD, Chan DW. The prognosticsignificance of troponin I and troponin T.Acad Emerg Med. 1998; 5:758–67.11. Morrow DA, Rifai N, TanasijevicMJ, Wybenga DR, De Lemos JA, AntmanEM. Clinical efficacy of three assays forcardiac troponin I for risk stratificationin acute coronary syndromes: a Throm-bolysis In Myocardial Infarction (TIMI)IIB substudy. Clin Chem. 2000; 46:453–60.12. Kosnick JW, Zalenski RJ, Shamsa F,et al. Resting sestamibi imaging for theprognosis of low-risk chest pain. AcadEmerg Med. 1999; 6:998–1004.