Tag Archives: acs

Acute Med, All Updates

Fancy new ACS tests

It’s hard to keep track of all new proposed biomarkers that may be useful in the work up of acute coronary syndrome (ACS) patients. We’re all used to troponin now – so we really want to know how novel tests measure up against the existing standard, in particular for the timeframe in which troponin is less helpful, namely the first six hours.
A systematic review examine the evidence for the following biomarkers in the early assessment (ie, within 6 h of symptom onset) of suspected ACS:

  • CK-MB: CK-MB and 2 h ΔCK-MB have potential in diagnosing AMI in the first hours after symptom onset. Whether CK-MB has value in the early diagnostic assessment of ACS in addition to clinical symptoms, ECG or other markers has rarely been studied.
  • myoglobin: myoglobin might be of value in early ruling out of AMI and ACS in suspected patients because of the relatively high NPV; its PPV, however, is low. However, it is not yet known whether myoglobin has diagnostic value in addition to symptoms, signs and other diagnostic tests (eg, ECG), because of the lack of multivariable analysis
  • heart-type fatty acid binding protein (H-FABP): H-FABP seems to have some potential as an early diagnostic marker of AMI or ACS, but its value in addition to clinical features and other markers has not been studied
  • ischemia modified albumin (IMA): IMA could be a potential marker for early ruling out of ACS in chest pain patients because of its relatively high NPV, especially combined with cTn and ECG. However, its PPV is low. Importantly; IMA seems to add relevant diagnostic information to more readily available diagnostic parameters. However, problems with the stability of IMA and its lack of cardiospecificity have been reported
  • pregnancy-associated plasma protein A: contradictory results indicate that the diagnostic value of PAPP-A in patients suspected of having ACS has not been evaluated properly
  • glycogen phosphorylase isoenzyme BB: GPBB might be a marker for myocardial ischaemia and myocardial necrosis, although the available research is limited and does not assess the added value of the marker.
  • myeloid-related protein 8/14: more research is needed to evaluate the (added) diagnostic value of MRP 8/14 in patients suspected of having ACS.

The authors also point out the introduction of high-sensitivity troponin assays may further improve diagnosis of ACS. They refer to a study in patients with suspected AMI presenting at the emergency department, which showed that a sensitive cTnI assay had a higher NPV than a standard cTnT assay and comparable PPV for detecting AMI within 6 h of symptom onset. The PPV was 79.3% and 80.7%, respectively; the NPVs were 95.3% and 88%. The Full Text of this high-sensitivity troponin paper is here
The review makes the following conclusions:

  • current guidelines advocate the use of cardiac troponin or CK-MB when cTn is not available, and myoglobin in the first 6 h in addition to cTn
  • IMA and H-FABP seem to be promising diagnostic biomarkers in the early diagnostic assessment of patients suspected of having ACS
  • There is an urgent need for adequately designed studies of (novel) ACS markers and their combinations against contemporary troponin assays

Novel biochemical markers in suspected acute coronary syndrome: systematic review and critical appraisal
Heart. 2010 Jul;96(13):1001-1

Acute Med, All Updates, Resus

Inferior MI – check V1 too

Lead V1 directly faces the right ventricle and during an inferior AMI may exhibit ST elevation with concomitant right ventricular infarction. Lead V1 also faces the endocardial surface of the posterolateral left ventricle, and ST depression may reflect concomitant posterolateral infarction (as the “mirror image” of ST elevation involving posterolateral epicardial leads). In this situation, V3 also shows ST depression. In lead V1, however, ST elevation from right ventricular AMI may potentially cancel out the ST depression from posterolateral AMI to give an isoelectric ST level. Diagnosis of right ventricular infarction during an inferior AMI may therefore be aided by evaluating both V1 and V3 ST levels. Both right ventricular infarction and postero-lateral infarction worsen the prognosis of an inferior AMI.
In 7967 patients with acute inferior myocardial infarction in the Hirulog and Early Reperfusion or Occlusion-2 (HERO-2) trial, V1 ST levels were analyzed with adjustment for lead V3 ST level for predicting 30-day mortality.
V1 ST elevation at baseline, analyzed as a continuous variable, was associated with higher mortality. Unadjusted, each 0.5-mm-step increase in ST level above the isoelectric level was associated with ~25% increase in 30-day mortality; this was true whether V3 ST depression was present or not. The odds ratio for mortality was 1.21 (95% confidence interval, 1.07 to 1.37) after adjustment for inferolateral ST elevation and clinical factors and 1.24 (95% confidence interval, 1.09 to 1.40) if also adjusted for V3 ST level. In contrast, lead V1 ST depression was not associated with mortality after adjustment for V3 ST level. V1 ST elevation ≥1 mm, analyzed dichotomously in all patients, was associated with higher mortality. The odds ratio was 1.28 (95% confidence interval, 1.01 to 1.61) unadjusted, 1.51 (95% confidence interval, 1.19 to 1.92) adjusted for V3 ST level, and 1.35 (95% confidence interval, 1.04 to 1.76) adjusted for ECG and clinical factors. Persistence of V1 ST elevation ≥1 mm 60 minutes after fibrinolysis was associated with higher mortality (10.8% versus 5.5%, P<0.001). The authors conclude that V1 ST elevation identifies patients with acute inferior myocardial infarction who are at higher risk, although because no myocardial imaging was performed, could only speculate that the mechanistic link between V1 elevation and increased mortality is due to the occurrence of right ventricular infarction. This is important to know about in terms of prognostication, but is it useful in the diagnosis of right ventricular AMI? The authors acknowledge that the ECG diagnosis of right ventricular infarction is classically made by recording lead V4R. In an autopsy study of 43 patients, ST elevation in lead V4R had higher sensitivity and specificity than ST elevation in lead V1 in diagnosing right ventricular infarction. Similarly, ST elevation in leads V7 through V9 adds significantly to precordial ST depression in aiding the diagnosis of posterolateral AMI. The authors contend that recording leads V4R and V7 through V9 is an additional step in the performance of a standard 12-lead ECG and, although recommended, may not be routinely performed. I will continue to do a V4R in all inferior AMIs, and a V7-8 at least in patients with ST depression in V1-3. Prognostic Value of Lead V1 ST Elevation During Acute Inferior Myocardial Infarction
Circulation. 2010 Aug 3;122(5):463-9

Acute Med, All Updates, PHARM, Resus

Oxygen in AMI – no benefit, possible harm

A Cochrane review examined the evidence from randomised controlled trials to establish whether routine use of inhaled oxygen in acute myocardial infarction (AMI) improves patient-centred outcomes, the primary outcomes being death, pain and complications.

Three trials involving 387 patients were included and 14 deaths occurred. The pooled relative risk (RR) of death was 2.88 (95% CI 0.88 to 9.39) in an intention-to-treat analysis and 3.03 (95% CI 0.93 to 9.83) in patients with confirmed AMI. While suggestive of harm, the small number of deaths recorded meant that this could be a chance occurrence. Pain was measured by analgesic use. The pooled RR for the use of analgesics was 0.97 (95% CI 0.78 to 1.20).
There is therefore no conclusive evidence from randomised controlled trials to support the routine use of inhaled oxygen in patients with acute AMI. A definitive randomised controlled trial is required.
Oxygen therapy for acute myocardial infarction
Cochrane Review

Acute Med, All Updates, Guidelines, Resus

STEMI and PCI guidelines

Lots of interesting and up to date information in this thick document from December 2009
Full text is available here
2009 Focused Updates: ACC/AHA Guidelines for the Management of Patients With ST-Elevation Myocardial Infarction (Updating the 2004 Guideline and 2007 Focused Update) and ACC/AHA/SCAI Guidelines on Percutaneous Coronary Intervention (Updating the 2005 Guideline and 2007 Focused Update)

Acute Med, All Updates, Guidelines, Resus

The early management of unstable angina and NSTEMI

The UK’s National Institute for Clinical Excellence has produced evidence based guidelines on the early management of unstable angina and NSTEMI
Their ‘key priorities for implementation’ are:

  • As soon as the diagnosis of unstable angina or NSTEMI is made, and aspirin and antithrombin therapy have been offered, formally assess individual risk of future adverse cardiovascular events using an established risk scoring system that predicts 6-month mortality (for example, Global Registry of Acute Cardiac Events [GRACE]).
  • Consider intravenous eptifibatide or tirofiban as part of the early management for patients who have an intermediate or higher risk of adverse cardiovascular events (predicted 6-month mortality above 3.0%), and who are scheduled to undergo angiography within 96 hours of hospital admission.
  • Offer coronary angiography (with follow-on PCI if indicated) within 96 hours of first admission to hospital to patients who have an intermediate or higher risk of adverse cardiovascular events (predicted 6-month mortality above 3.0%) if they have no contraindications to angiography (such as active bleeding or comorbidity). Perform angiography as soon as possible for patients who are clinically unstable or at high ischaemic risk.
  • When the role of revascularisation or the revascularisation strategy is unclear, resolve this by discussion involving an interventional cardiologist, cardiac surgeon and other healthcare professionals relevant to the needs of the patient. Discuss the choice of the revascularisation strategy with the patient.
  • To detect and quantify inducible ischaemia, consider ischaemia testing before discharge for patients whose condition has been managed conservatively and who have not had coronary angiography.
  • Before discharge offer patients advice and information about:

– their diagnosis and arrangements for follow-up

– cardiac rehabilitation

– management of cardiovascular risk factors and drug therapy for secondary prevention

– lifestyle changes

One of the most potentially confusing areas is the choice of antithrombin therapy. Whereas the low molecular weight heparin enoxaparin is currently widely used, the guideline recommends the following:

The guideline summary is here and the full guideline is here

Acute Med, All Updates

Atypical chest pain renders AMI more likely

A prospective study of 796 ED patients with suspected cardiac chest pain assessed the value of individual historical and examination findings for diagnosing acute myocardial infarction (AMI) and the occurrence of adverse events (death, AMI or urgent revascularization) within 6 months. AMI was diagnosed in 148 (18.6%) of the 796 patients recruited.
The results may surprise some physicians:
Sweating observed by the ED physician was the strongest predictor of AMI (adjusted OR 5.18, 95% CI 3.02–8.86).
Reported vomiting was also a fairly strong predictor of AMI (adjusted OR 3.50, 1.81–6.77).
Pain located in the left anterior chest was found to be the strongest negative predictor of AMI (adjusted OR 0.25, 0.14–0.46).
Patients who described the pain as being the same as previous myocardial ischaemia were significantly less likely to be having AMI!
Following adjustment for age, sex and ECG changes, the following characteristics made AMI more likely (adjusted odds ratio, 95% confidence intervals):

  • pain radiating to the right arm (2.23, 1.24-4.00)
  • pain radiating to both arms (2.69, 1.36-5.36)
  • vomiting reported (3.50, 1.81-6.77), central chest pain (3.29, 1.94-5.61)
  • sweating observed by physician (5.18, 3.02-8.86)

Pain in the left anterior chest made AMI significantly less likely (0.25, 0.14-0.46)
The presence of rest pain (0.67, 0.41-1.10) or pain radiating to the left arm (1.36, 0.89-2.09) did not significantly alter the probability of AMI.
Compare these results with the American Heart Association guidelines which state that “chest or left arm pain or discomfort as the chief symptom reproducing prior documented angina” is associated with a high likelihood of ACS, or the European Society of Cardiology guidelines which state that “the typical clinical presentation of NSTE-ACS is retrosternal pressure or heaviness radiating to the left arm, neck or jaw”, which the authors of this study point out are statements made based on expert opinion for which references are not given.
The authors summarise with a powerful message: ‘Several ‘atypical’ symptoms actually render AMI more likely, whereas many ‘typical’ symptoms that are often considered to identify high-risk populations have no diagnostic value.’
The value of symptoms and signs in the emergent diagnosis of acute coronary syndromes
Resuscitation. 2010 Mar;81(3):281-6

All Updates, PHARM

Stopping infusions before PCI transfer

An interhospital transport service introduced a no infusions policy for patients being transferred for primary coronary intervention, instead giving a bolus of heparin and glycoprotein 2b-3a inhibitor prior to transfer, along with non-intravenous nitrates (if needed). Discontinuing infusions during transport resulted in a significant reduction in transport times with no adverse effect on hospital length of stay or mortality. It did not significantly extend the time the patient spent in the catheterisation laboratory, nor did it impact the incidence of TIMI III flow. It did not impact the incidence of readmission to the hospital for cardiac-related chief complaints.
Transporting without infusions: effect on door-to-needle time for acute coronary syndrome patients
Prehosp Emerg Care. 2010 Apr 6;14(2):159-63

Acute Med, All Updates

80 lead ECG increases AMI detection – so what?

The 80-lead ECG is more sensitive than a 12 lead ECG for detecting infarcts in the posterior, right, inferior, and high lateral areas of the heart.
80-lead ECG body surface mapping was applied to 1830 patients in the emergency department with moderate to high risk chest pain. 12 lead ECG detected STEMI in 91 patients and an additional 25 patients had 80-lead-only STEMI.

The authors and an editorialist point out some interesting issues and unanswered questions regarding the application of this technology:

  • Since almost all of the 80-lead-only STEMI patients had an elevated troponin, is this just another way of diagnosing NSTEMI?
  • Since there are no convincing data demonstrating a benefit from immediate therapy of NSTEMI, would the earlier detection improve outcome?
  • Angiographic findings in the 80-lead-only STEMI group showed similar lesions to 12-lead STEMI patients, with more frequent involvement of posterior (left circumflex) and right ventricular (right coronary artery) regions
  • Is the increase in sensitivity offered by the 80-lead ECG accompanied by a decrease in specificity?

More research is needed – preferably in a randomised controlled trial – before this interesting technology is rolled out in emergency departments
Acute detection of ST-elevation myocardial infarction missed on standard 12-Lead ECG with a novel 80-lead real-time digital body surface map: primary results from the multicenter OCCULT MI trial.
Ann Emerg Med. 2009 Dec;54(6):779-788
The 80-lead ECG: more expensive NSTEMI or Occult STEMI
Ann Emerg Med. 2009 Dec;54(6):789-90

Acute Med, All Updates

pain radiation to right arm in ACS

How predictive is the history for acute coronary syndrome? Of 1576 patients entered into a multicentre evaluation of chest pain units, 132 (8.4%)  had ACS, as determined by positive troponin, CK-MB, or early treadmill test.
On multivariate analysis, only age, duration, sex and radiation of pain to the right arm were independently associated with ACS.
Likelihood ratios (95% CI) were:

  • radiation of pain to the right arm, 2.9 (95% CI 1.4 to 6.3)
  • male sex 1.2 (95% CI 1.0 to 1.3)
  • female sex 0.79 (95% CI 0.62 to 1.0).

The area under the receiver operator characteristic curve for age was 0.629 (95% CI 0.573 to 0.686) and for duration was 0.546 (95% CI 0.481 to 0.610).
The authors conclude that clinical features have very limited value for diagnosing ACS in patients with a normal or non- diagnostic ECG, and radiation of pain to the right arm increases the likelihood of ACS.
Clinical diagnosis of acute coronary syndrome in patients with chest pain and a normal or non-diagnostic electrocardiogram.
Emerg Med J. 2009 Dec;26(12):866-70

Acute Med, All Updates, PHARM

Characteristic ECG signs of LAD occlusion without ST elevation

In a single centre observational study over 10 years of patients undergoing acute PCI of the left anterior descending (LAD) artery, 35 of 1890 (2%) had a distinct non-ST elevation ECG pattern.
The ECG showed ST-segment depression at the J-point of at least 1 mm in the precordial leads with upsloping ST-segments continuing into tall, symmetrical T-waves. Patients also showed a mean J-point elevation of approximately 0.5 mm in lead aVR.
This novel ECG pattern resolved after reperfusion in all included patients.
The authors caution that these electrocardiographic changes may be missed or misdiagnosed as reversible ischaemia, which might substantially delay the transportation to a PCI centre or the start of reperfusion therapy
The authors conclude: “It is important for cardiologists and emergency care physicians to recognise this distinct ECG pattern, so they can triage such patients for immediate reperfusion therapy.”

Image from Dr Smith's ECG Blog

Persistent precordial “hyperacute” T-waves signify proximal left anterior descending artery occlusion
Heart. 2009 Oct;95(20):1701-6