A new chest pain strategy in Thunder Bay

Abstract

SUMMARY:Thunder Bay Regional Hospital (TBRH) developed a chest pain strategy (CPS) to support its emergency physicians in making the difficult clinical decisions required to properly evaluate and manage ED “chest pain” patients. This strategy was developed to ensure excellent patient care in a setting of diminished inpatient bed availability and increasing ED congestion. It focuses on rapid risk stratification, using history, electrocardiogram, physical examination and 3 new point-of-care cardiac markers: myoglobin, CK-MB mass, and cardiac troponin I.Following the introduction of the CPS in 1997, TBRH realized significant ($500 000/yr) institutional resource savings through a 60% decrease in the admission rate of non-myocardial infarction, non-unstable angina chest pain patients, a 30% decrease in ED chest pain evaluation time, and improved ED availability of monitored stretchers. The CPS has allowed TBRH to simultaneously decrease costs and improve patient care.

Diagnostic parameters of CK–MB and myoglobin related to chest pain duration

“…However, even in patients with prolonged pain, test sensitivity did not approach 100%. Many authors suggest that myoglobin 10,[27][28][29]31,32,43 and CK-MB assays 6,8,10,[15][16][17][18]20,21,24,25,27,43 achieve excellent sensitivity in patients with 3-6 or 6-8 h of symptoms, respectively. A recent NACB position paper 14 proposes the use of "an early marker that is reliably increased within 6 h and a definitive marker that is elevated within 6-9 h." Based on this recommendation and previous studies, clinicians may feel that a single test can rule out AMI in patients with adequate symptom duration.…”

“…In patients with 0-4 h of pain, myoglobin was more sensitive (39% vs. 28%), in patients with 4-8 h of pain, sensitivities for the 2 markers were similar (61% vs. 56%), and in patients with over 8 h of pain, CK-MB was more sensitive (73% vs. 65%). The maximum sensitivity achieved by a single assay was 77%: this was the 1-h CK-MB draw in patients with [8][9][10][11][12] or >12 h of pain. * Sensitivity was enhanced by combining markers and performing serial assays (Figs.…”

“…[1][2][3][4] Consequently, more patients undergo emergency department (ED) diagnostic protocols, which are based largely on the use of cardiac marker assays to "rule out" myocardial infarction. 2,[5][6][7][8][9][10][11] One large study in 4 teaching hospitals 12 concluded that emergency physicians rely heavily on the results of single marker assays, although these have been shown to have poor sensitivity. 13 The National Academy of Clinical Biochemistry (NACB) recently recommended that physicians employ 2 cardiac markers to evaluate patients with chest pain -an early marker that is reliably increased within 6 hours and a definitive marker that is elevated within 6 to 9 h. 14 CK-MB and the troponins are considered definitive markers.…”

“…39,40 Myoglobin, a nonspecific marker of muscle injury, is released rapidly during acute myocardial infarction (AMI) and provides greater early sensitivity, from 26%-58% at presentation, 11,26,31,32,41,42 to 79%-100% with serial as-says. 11,27,28,31,33,43 It has been proposed as the early marker for ED "rule-out" protocols, 10,27,33 included in recently developed commercial marker panels, 10,27,44 and advocated by the NACB panel as the most conveniently measured early marker. 14 But myoglobin's early sensitivity may not be adequate to rule out AMI and the clinical benefit of adding myoglobin to other, more specific, markers remains unclear.…”

Cardiac markers and their point-of-care testing for diagnosis of acute myocardial infarction

“…Although the cost of a single POC test may be higher than a laboratory test, implementation of POC testing may significantly lower the overall/long-term costs for healthcare by the reduction of central laboratory services, the reduced length of patients' stay in ED or CCU, and the more appropriate or rapid triage to the patients. One of the reports to substantiate this was an institutional saving of $500,000 (Canadian)/year following implementation of POCT for cardiac markers, with an associated 60% decrease in the admission rate of patients without AMI or unstable angina, and a 30% decrease in ED evaluation time [93].…”