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ACUTE CORONARY SYNDROMES AND THE EVALUATION OF CHEST PAIN 1 medicalquery@torrentpharm a.com
| Date post: | 11-May-2015 |
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SPECTRUM OF PRESENTATIONS
• NON CARDIAC CHEST PAIN• ATYPICAL CHEST PAIN• EXERTIONAL ANGINA• POSSIBLE REST ANGINA• DEFINITE REST ANGINA• NON ST SEGMENT ELEVATION MI
(NSTEMI)• ST SEGMENT ELEVATION MI
Evaluation and Management of Chest Pain
• Rapid triage of chest pain patients
• Appreciation of atypical presentations, particularly in the elderly
• Appreciation of the frequency of coronary artery disease in middle aged patients
• Low threshold to get an ECG– Value of serial ECGs, and old ECGs– Normal ECG does not exclude CAD
Evaluation and Management of Chest Pain
• Who should be discharged from the ER?
• Who should be observed in a 12-24 hour low risk chest pain unit?
• Who should be admitted to telemetry?
• Who should be admitted to the CCU/ICU?
• Who should go directly to the cardiac catheterization laboratory?
Pitfalls of “Rule-Out” Patients
• Even if troponins are negative:– Are the negative troponins obtained within
the right time window to exclude MI?– Does the patient have unstable angina?– Does the patient have another potentially life-
threatening cause of chest pain?– What is the cause of the chest pain?– Has the patient been given pre-discharge
instructions and follow-up?
“Non - pain” presentations of coronary ischemia
• Burning, including heartburn
• Pressure
• Aching
• Discomfort
• Abdominal, jaw, arm pain
• Dyspnea
• Malaise
Atypical presentations of coronary ischemia
• Sharp, stabbing
• Pleuritic
• Pain on palpation of the chest
• Shoulder, back pain
Chest Pain Myths
• Absence of pain radiation argues against a cardiac etiology
• Absence of preceding angina argues strongly against a cardiac etiology
• Absence of risk factors argues against a cardiac etiology
• Coronary artery disease is rare in middle aged patients
Chest Pain Myths
• A normal ECG in a pain free patient argues strongly against a cardiac etiology
• Relief of pain after nitrates proves that the pain was caused by ischemia
• With a careful history and physical, any patient can be discharged from the ED without ancillary testing (ECG, CXR, serial troponins)
Chest Pain Myths
• Ischemic chest pain in the first year after bypass surgery is rare. The pain must be musculoskeletal.
• Atypical features allow physicians to discharge patients from the ED without further evaluation.
• Atypical presentations of MI are rare• Treadmill testing is always safer than
cardiac [email protected]
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Important questions in the evaluation of chest pain
• Have you had this type of pain before?• In between episodes of resting chest pain,
have you been able to exert yourself vigorously without getting symptoms?
• How long does the pain last (continuously)?• After nitroglycerin, how long did it take for
the pain to start to improve?• Have you had previous cardiac
events/tests?
Important questions in the evaluation of chest pain
• Is the pain associated with:– Inspiration– Eating– Local movements (incl. palpation)– Nausea/vomiting– Dyspnea– Malaise– Lightheadedness
Other diagnoses: Pulmonary Embolus
• Hypoxia (+/- decreased pCO2)• Tachycardia• Chest Pain• Dyspnea• Risk Factors (need not be present):
– Cancer, obesity, immobility, travel, hypercoaguable state, post-op, elevated right sided pressures e.g. CHF, COPD.
Other diagnoses: Aortic Dissection
• Pain severest at its onset
• Chest and/or back pain
• Predisposing Factors– HTN, Marfan’s syndrome, pregnancy,
coarctation, bicuspid aortic valve
• Associated findings– Aortic insufficiency, hemopericardium, left
pleural effusion, hypertension or hypotension, asymmetric BP and pulses, limb ischemia
Clinical Classification of Angina
• TYPICAL (definite)– 1. substernal chest discomfort with
characteristic quality and duration, that is– 2. provoked by exertion or emotional stress– 3. relieved by rest or nitroglycerin
• ATYPICAL (probable)– Meets 2 of above criteria
• NON-CARDIAC – Meets 1 or none of typical angina characteristics
Relief of pain “by nitroglycerin” is tricky
• Recent data suggests that value of pain relief by NTG is overrated at best
• True NTG effect should begin to work within a few minutes– Pain that starts to go away 30 minutes after a
sublingual NTG is probably nor “relieved by NTG” but it may be inappropriately reported as such in the medical record
• You should ask about timing of pain improvement after nitro
Risk Factors for CAD
• Sex
• Age
• Smoker
• DM
• Elevated lipids
• Family history
• Personal history of CAD
Pre-Test ProbabilitySex/Age Non-anginal Atypical pain Typical pain
Men
60-69 .28 .67 .94
50-59 .22 .59 .92
40-49 .14 .46 .87
30-39 .05 .22 .70
Women
60-69 .19 .54 .91
50-59 .08 .32 .79
40-49 .03 .13 .55
30-39 .01 .04 [email protected]
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Approach to the patient with chest pain (or other possible “anginal equivalents”)
• Get a quick ECG while vitals signs and a focused history are obtained
• If the ECG shows a ST segment elevation MI, get assistance– Stabilize the patient (IV access, treating
abnormal hemodynamics, initiating pharmacologic therapy) while cardiology is simultaneously contacted for consideration of primary percutaneous coronary intervention, (or thrombolytics if PCI is unavailable)
Approach to the patient with chest pain (or other possible “anginal equivalents”)• If the ECG does not show evidence of a ST segment
elevation MI, focus on obtaining a thorough history and physical exam, while labs and CXR are obtained simultaneously.– You must consider other etiologies for chest pain besides coronary
artery disease, especially those that are life-threatening
• If the pain sounds anginal and hemodynamics are stable, consider sublingual nitroglycerin
• If the pain is typical and occurs at rest (especially in a patient with known CAD or risk factors for CAD, especially if the ECG is abnormal) treat the patient as a presumed acute coronary syndrome– ICU if likelihood of ACS is high, otherwise telemetry– ASA. For high likelihood of ACS, heparin (or LMWH), consider beta
blockade, IV nitroglycerin, clopidogrel, and IIb/IIIa antagonists
Approach to the patient with chest pain (or other possible “anginal equivalents”)• If the symptoms are atypical with a normal or
near normal ECG, the patient should be given aspirin and “ruled out” for MI with serial troponin– Telemetry admission or ER “chest pain observation”
stay, depending on level of concern– Consider stress test or coronary CT angiography for
certain patients but not all• Patients with exceptionally low suspicion of ischemia after
negative troponins and ECGs may be “managed expectantly”, because further testing may be falsely positive or deliver unnecessary radiation
• Even the lowest risk patients need to follow-up with their provider
Approach to the patient with chest pain (or other possible “anginal equivalents”)
• The duration of chest discomfort (especially if constant and substantial) may be helpful– Most patients with substantial, prolonged chest
discomfort will “rule in” with positive troponins if the rest pain is truly ischemic
• Counting risk factors for CAD is not the best way to determine if a patient is actually having an ACS– History and evaluation of the ECG is key, even in a
patient with few or no risk factors
Approach to the patient with chest pain (or other possible “anginal equivalents”)
• Even in patients with a “terrible” history for myocardial ischemia, you must get an electrocardiogram– Atypical presentations of common diseases (like
CAD) are more common than classic presentations of weird diseases
– Coexisting etiologies of non-cardiac chest pain may fake you out
• Musculoskeletal CP, reflux (GERD) are very common
– Patients may be in denial: “I’m sure its just heartburn”
Approach to the patient with chest pain (or other possible “anginal equivalents”)• ST segment elevation may be due to other causes
(besides a STEMI) but if you are not 100% sure, show the ECG to a cardiologist– Magnitude of ST elevation may be subtle in a real STEMI- look
for reciprocal change– A new LBBB in a patient with typical pain should raise concern
for a large acute LAD infarct, to be treated like a STEMI– Actively look for prior ECGs– Consider frequent repeat ECGs and more frequent troponins– Consider acute imaging with echo or resting nuclear perfusion
scintigraphy for low (but non-zero) pre-test probability cases with non diagnostic ST elevation
– For cases that are “50/50” emergent cath is perfectly reasonable
Approach to the patient with chest pain (or other possible “anginal equivalents”)
• Most patients with a real ACS but without ST elevation can be made pain free without opiates– Most patients with a NSTEMI have T wave inversions
and or ST depression, although a normal ECG is possible
– ASA, Nitrates, heparin (or LMWH), beta blockers– NSTEMI patients who cannot be rendered pain free
should be considered for emergent cath (coronary angiography)
– Morphine should not be given glibly just because someone has chest pain
T Wave inversions in a patient with rest angina and indeterminate troponins, who
ultimately required CABG
ST depression in a patient with rest angina and positive troponins, who ultimately
required CABG
Approach to the patient with chest pain (or other possible “anginal equivalents”)• “Ruling a patient out” with negative
troponins does not rule out an ACS, it only rules out a myocardial infarction– Patients with typical pain that is not
prolonged, substantial and unremitting may have true “rest angina” with normal troponins. True rest angina patients should generally be treated the same as NSTEMI patients, with aggressive pharmacotherapy and generally catheterization.
• Stress testing is contraindicated for patients with rest angina who have not been stabilized medically
Approach to the patient with chest pain (or other possible “anginal equivalents”)• Giving heparin (or LMWH) to patients with atypical pain
who are likely to “rule out” is common but inappropriate– Bleeding risk not trivial, especially if dosing is inappropriate
• Not all patients with a positive troponin are having a “classic” ACS– Other cardiovascular stressors may result in borderline troponin
increase• PE, CHF exacerbation, or hypertensive emergency in patients with
normal coronaries– Patients with substantial stabilized chronic CAD, may “rule in” in
the setting of a large stressor (COPD exacerbation, GI bleed, emergency surgery)
• Treat the underlying illness first to decrease myocardial oxygen demand, reserve emergent angiography for highest risk cases.
Stress Testing: Decisions, Decisions
• Is Stress Testing the Right Thing to Do?– In some cases, is it even necessary?– Is it contraindicated or not enough?
• Can The Patient Exercise?• Is Imaging Needed or is Plain ETT Enough?• If Pharmacologic Stress, Which Type?• If Imaging is Needed, Which Type?• Should Antianginal Meds be Held?
General Contraindications to Stress Testing
• Unwillingness/ Inability to Participate
• Acute Pulmonary Embolus
• Aortic Dissection
• Acute Myocarditis/Pericarditis
• Acute MI (within 3 days)
• Severe metabolic derangement
• Resting ischemic chest pain– ie. Unstable Angina
General Contraindications to Stress Testing
• Decompensated Heart Failure
• Uncontrolled Arrhythmia
• Recent CVA
• Significant Aortic Stenosis
• Hypertrophic Cardiomyopathy
• Some patients with Severe MS and /or Significant Pulmonary Hypertension
• Severe Uncontrolled [email protected]
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Types of Stressors
• Exercise– Treadmill– Bicycle, Upright or Supine
• Vasodilators– Persantine– Adenosine
• Positive Inotropes/Chronotropes– Dobutamine
Specific Contraindications
• All General Contraindications Still Apply• Dobutamine
– Greater propensity to Aggravate Arrhythmias than Persantine
• Persantine/Adenosine– Reactive Airway Disease– Heart Block with Adenosine– Recent Caffeine Ingestion– Theophylline Use
Which Type of Pharmacologic Stress?
• Persantine/Adenosine vs. Dobutamine– Consider Specific Contraindications– Persantine or Adenosine Cardiolite test of
choice for LBBB patient• Septal reversible defects with dobutamine or
exercise and LBBB, not with persantine
– Persantine and adenosine statistically less likely to produce ischemia than dobutamine, but have comparable sensitivity for CAD
Imaging with Stress Testing
• When imaging is necessary– LBBB, LVH with Strain, WPW, Paced Rhythm– Patient cannot exercise
• When imaging may help (controversial)– LVH w/o Strain, digoxin, Established CAD
• Types of Imaging– Nuclear: Perfusion Scintigraphy – Echocardiography
Which Type of Imaging?
• Know your own institution’s strengths
• Echo preferable in pregnancy
• Echo less suitable if images are poor
• Technological improvements have helped both types of imaging
• Cardiolite (Sestamibi) vs. Myoview (Tetrofosmin) vs. Thallium
Accuracy of Stress Testing:“Plain” ETT
• Sensitivity 68-76%– Higher for left main, 3 vessel disease– Higher if upsloping ST depression used
• Specificity 73-77%– Lower if upsloping ST depression used– Probably lower in women
• Reported Range 48-86%
Accuracy of Stress Testing: Nuclear Perfusion Imaging
• ETT with Nuclear Perfusion – Sensitivity 83-90%, Specificity 62-88%
• Persantine with Nuclear Perfusion– Sensitivity 82-89%, Specificity 75-78%
• Dobutamine with Nuclear Perfusion– Sensitivity 80-97%, Specificity 74-89%
Accuracy of Stress Testing:Stress Echocardiography
• Exercise Echocardiography– Sensitivity 71-97%, Specificity 64-100%
• Dobutamine Echocardiography– Sensitivity 76-89%, Specificity 70-95%
• Persantine (High Dose) Echocardiography– Rarely done in U.S.– Sensitivity 74-83%, Specificity @ 80%
