We read with interest the study published in this month's EMJ by
Aldous et al. High-Sensitivity troponin T for early rule-out of
myocardial infarction in recent onset chest pain. (1) This study adds to
the growing body of published evidence that points to the safe use of new
high-sensitivity troponin assays earlier in the patient journey.(2,3,4)
The authors quite rightly point out that further prospective testing is
required.
The current aim of emergency department research surrounding
suspected cardiac chest pain is to allow identification of a patient group
that can be safely discharged following rapid rule-out of MI with very
low (ideally <1%) Major Adverse Cardiac Event (MACE) rates. In the
recently published ASPECT Study (5) Than et al. identified such a group
using a combination of risk-scoring (using the TIMI score), ECG and
negative point-of-care biomarkers for myocardial necrosis (CK-MB,
myoglobin and "low-sensitivity" troponin) tested at 0 and 2 hours giving
MACE rates of 0.08%. However, the cost effectiveness of point-of-care
biomarker testing has recently been questioned,(6) and therefore the focus
has switched to new laboratory high-sensitivity troponin assays.
We note that the cohort of patients investigated by Aldous et al. had
a high prevalence of high-risk clinical features prior to troponin
testing (52% had ischaemic heart disease and 33% had prior
revascularisation). This may have contributed to the relatively higher
MACE rates of 1.2% observed in this study, and highlights the Bayesian
argument regarding pre-test probability. We suggest that improved early
risk stratification using a combination of history, risk factors and ECG
may improve the accuracy of early high-sensitivity troponin. However, a
risk score appropriate for this purpose has yet to be identified. One
problem with current risk score systems, such as the TIMI(7) and GRACE(8),
is that they were developed to identify high rather than low risk
individuals. Furthermore, they often require knowledge of troponin and
angiography results. Further validation of risk scores is required.
At a time when there is increased focus on the new Emergency
Department Quality Indictors, it is strongly recommended that Patient
Satisfaction should be taken into account. (9) We have found no published
evidence that patients have increased satisfaction when discharged earlier
following an episode of chest pain assessed by accelerated chest pain
protocols. Rather, may patients actually prefer to be admitted to
hospital for a longer period of observation following what is an
undoubtedly a high-anxiety presentation? Qualitative research in this
area is also required.
REFERENCES
1. Aldous S, Pemberton C, Richards AM, et al. High-sensitivity
troponin T for early rule-out of myocardial infarction in recent onset
chest pain. Emerg Med J 2011
2. Keller T, Zeller T, Peetz D, Tzikas S, Roth A, Czyz E, Bickel C,
Baldus S, Warnholtz A, Frohlich M, Sinning CR, Eleftheriadis MS, Wild PS,
Schnabel RB, Lubos E, Jachmann N, Genth-Zotz S, Post F, Nicaud V, Tiret L,
Lackner KJ, Munzel TF, Blankenberg S. Sensitive troponin I assay in early
diagnosis of acute myocardial infarction. N Engl J Med 2009; 361:868-77.
3. Reichlin T, Hochholzer W, Bassetti S, Steuer S, Stelzig C,
Hartwiger S, Biedert S, Schaub N, Buerge C, Potocki M, Noveanu M,
Breidthardt T, Twerenbold R, Winkler K, Bingisser R, Mueller C. Early
diagnosis of myocardial infarction with sensitive cardiac troponin assays.
N Engl J Med 2009; 361:858-67.
4. Body R, Carley S, McDowell G, Jaffe AS, France M, Cruickshank K,
Wibberley C, Nuttall M, Mackway-Jones K. Rapid exclusion of acute
myocardial infarction in patients with undetectable troponin using a high-
sensitivity assay. J Am Coll Cardiol 2011; 58:1332-9.
5. Than M, Cullen L, Reid CM, Lim SH, Aldous S, Ardagh MW, Peacock
WF, Parsonage WA, Ho HF, Ko HF, Kasliwal RR, Bansal M, Soerianata S, Hu D,
Ding R, Hua Q, Seok-Min K, Sritara P, Sae-Lee R, Chiu TF, Tsai KC, Chu FY,
Chen WK, Chang WH, Flaws DF, George PM, Richards AM. A 2-h diagnostic
protocol to assess patients with chest pain symptoms in the Asia-Pacific
region (ASPECT): a prospective observational validation study. Lancet.
2011 Mar 26;377(9771):1077-84.
6. Fitzgerald P, Goodacre SW, Cross E, Dixon S. Cost-effectiveness of
point-of-care biomarker assessment for suspected myocardial infarction:
the randomized assessment of treatment using panel Assay of cardiac
markers (RATPAC) trial. Acad Emerg Med. 2011 May;18(5):488-95.
7. Antman EM, Cohen M, Bernink PJ, McCabe CH, Horacek T, Papuchis G,
Mautner B, Corbalan R, Radley D, Braunwald E. The TIMI risk score for
unstable angina/non-ST elevation MI: A method for prognostication and
therapeutic decision making. JAMA. 2000 Aug 16;284(7):835-42.
8. Fox KA, Eagle KA, Gore JM, Steg PG, Anderson FA; GRACE and GRACE2
Investigators. The Global Registry of Acute Coronary Events, 1999 to 2009-
-GRACE. Heart. 2010 Jul;96(14):1095-101.
9. Department of Health (UK). A & E Clinical Quality Indicators.
Epub 2010 Dec.
Conflict of Interest:
None declared
We read with interest the study published in this month's EMJ by Aldous et al. High-Sensitivity troponin T for early rule-out of myocardial infarction in recent onset chest pain. (1) This study adds to the growing body of published evidence that points to the safe use of new high-sensitivity troponin assays earlier in the patient journey.(2,3,4) The authors quite rightly point out that further prospective testing is required.
The current aim of emergency department research surrounding suspected cardiac chest pain is to allow identification of a patient group that can be safely discharged following rapid rule-out of MI with very low (ideally <1%) Major Adverse Cardiac Event (MACE) rates. In the recently published ASPECT Study (5) Than et al. identified such a group using a combination of risk-scoring (using the TIMI score), ECG and negative point-of-care biomarkers for myocardial necrosis (CK-MB, myoglobin and "low-sensitivity" troponin) tested at 0 and 2 hours giving MACE rates of 0.08%. However, the cost effectiveness of point-of-care biomarker testing has recently been questioned,(6) and therefore the focus has switched to new laboratory high-sensitivity troponin assays.
We note that the cohort of patients investigated by Aldous et al. had a high prevalence of high-risk clinical features prior to troponin testing (52% had ischaemic heart disease and 33% had prior revascularisation). This may have contributed to the relatively higher MACE rates of 1.2% observed in this study, and highlights the Bayesian argument regarding pre-test probability. We suggest that improved early risk stratification using a combination of history, risk factors and ECG may improve the accuracy of early high-sensitivity troponin. However, a risk score appropriate for this purpose has yet to be identified. One problem with current risk score systems, such as the TIMI(7) and GRACE(8), is that they were developed to identify high rather than low risk individuals. Furthermore, they often require knowledge of troponin and angiography results. Further validation of risk scores is required.
At a time when there is increased focus on the new Emergency Department Quality Indictors, it is strongly recommended that Patient Satisfaction should be taken into account. (9) We have found no published evidence that patients have increased satisfaction when discharged earlier following an episode of chest pain assessed by accelerated chest pain protocols. Rather, may patients actually prefer to be admitted to hospital for a longer period of observation following what is an undoubtedly a high-anxiety presentation? Qualitative research in this area is also required.
REFERENCES
1. Aldous S, Pemberton C, Richards AM, et al. High-sensitivity troponin T for early rule-out of myocardial infarction in recent onset chest pain. Emerg Med J 2011
2. Keller T, Zeller T, Peetz D, Tzikas S, Roth A, Czyz E, Bickel C, Baldus S, Warnholtz A, Frohlich M, Sinning CR, Eleftheriadis MS, Wild PS, Schnabel RB, Lubos E, Jachmann N, Genth-Zotz S, Post F, Nicaud V, Tiret L, Lackner KJ, Munzel TF, Blankenberg S. Sensitive troponin I assay in early diagnosis of acute myocardial infarction. N Engl J Med 2009; 361:868-77.
3. Reichlin T, Hochholzer W, Bassetti S, Steuer S, Stelzig C, Hartwiger S, Biedert S, Schaub N, Buerge C, Potocki M, Noveanu M, Breidthardt T, Twerenbold R, Winkler K, Bingisser R, Mueller C. Early diagnosis of myocardial infarction with sensitive cardiac troponin assays. N Engl J Med 2009; 361:858-67.
4. Body R, Carley S, McDowell G, Jaffe AS, France M, Cruickshank K, Wibberley C, Nuttall M, Mackway-Jones K. Rapid exclusion of acute myocardial infarction in patients with undetectable troponin using a high- sensitivity assay. J Am Coll Cardiol 2011; 58:1332-9.
5. Than M, Cullen L, Reid CM, Lim SH, Aldous S, Ardagh MW, Peacock WF, Parsonage WA, Ho HF, Ko HF, Kasliwal RR, Bansal M, Soerianata S, Hu D, Ding R, Hua Q, Seok-Min K, Sritara P, Sae-Lee R, Chiu TF, Tsai KC, Chu FY, Chen WK, Chang WH, Flaws DF, George PM, Richards AM. A 2-h diagnostic protocol to assess patients with chest pain symptoms in the Asia-Pacific region (ASPECT): a prospective observational validation study. Lancet. 2011 Mar 26;377(9771):1077-84.
6. Fitzgerald P, Goodacre SW, Cross E, Dixon S. Cost-effectiveness of point-of-care biomarker assessment for suspected myocardial infarction: the randomized assessment of treatment using panel Assay of cardiac markers (RATPAC) trial. Acad Emerg Med. 2011 May;18(5):488-95.
7. Antman EM, Cohen M, Bernink PJ, McCabe CH, Horacek T, Papuchis G, Mautner B, Corbalan R, Radley D, Braunwald E. The TIMI risk score for unstable angina/non-ST elevation MI: A method for prognostication and therapeutic decision making. JAMA. 2000 Aug 16;284(7):835-42.
8. Fox KA, Eagle KA, Gore JM, Steg PG, Anderson FA; GRACE and GRACE2 Investigators. The Global Registry of Acute Coronary Events, 1999 to 2009- -GRACE. Heart. 2010 Jul;96(14):1095-101.
9. Department of Health (UK). A & E Clinical Quality Indicators. Epub 2010 Dec.
Conflict of Interest:
None declared