ACC/AHA Guidelines for the Management of Patients with ST Elevation Myocardial Infarction;

2004

Ahmad Aslam, M.D.

Prasantha Bathini, M.D.

Robert Smith, M.D.

Cardiac Cath Conference

July 13, 2004

Participants in Updated Guidelines

““There is an unsettling truth about the practice There is an unsettling truth about the practice

of medicine. …study after study shows that few of medicine. …study after study shows that few

physicians systematically apply to everyday physicians systematically apply to everyday

treatment the scientific evidence about what treatment the scientific evidence about what

works best.”works best.”

Millenson, ML. Demanding Medical Excellence: Doctors Millenson, ML. Demanding Medical Excellence: Doctors and Accountability in the Information Age. 1997and Accountability in the Information Age. 1997

Evidence Based Medicine; What’s the Problem?

How Should We Be Dealing With This?

ACC/AHA Practice Guidelines: Classification of Benefit

Class I

Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective

Class IIa

Conditions for which there is conflicting evidence and/or divergence of opinion about the usefulness/efficacy of a procedure or treatment. However, the treatment/procedure is reasonable and is probably useful and effective

Class IIbConditions for which there is conflicting evidence and/or divergence of opinion about the usefulness/efficacy of a procedure or treatment. However, the treatment/procedure may be reasonable. The usefulness and effectiveness is not well established

Class IIIConditions for which there is evidence and/or general agreement that the procedure/treatment is not useful or effective and in some cases may be harmful

ACC/AHA Practice Guidelines: Level of Evidence

A (highest)The data were derived from multiple randomized clinical trials that involved large numbers of patients

B (intermediate)The data were derived from a limited number of randomized trials that involved small numbers of patients, or from careful analysis of non-randomized studies or observational registries

C (low)A lower rank was given when expert consensus was the primary basis for the recommendation

Epidemiology

• In the U.S., there were 1,680,000 discharges for ACS in the year 2001

• Approximately 500,000 of these were STEMI’s

Prehospital Issues

Class IPatients with symptoms of STEMI should be transported to the hospital by ambulance rather than by friends or relatives. (Level of Evidence: B)

Healthcare providers should instruct patients in whom NTG has been prescribed to take ONE NTG dose sublingually in response to chest pain. If the pain is worsened or unimproved after 5 minutes, the patient should be instructed to call 911 (Level of Evidence: C)

Initial Recognition and Management in the ED

“Hospitals should establish multidisciplinary teams (including primary care physicians, emergency medicine physicians, cardiologists, nurses, and laboratorians) to develop guideline-based, institution-specific written protocols for triaging and managing patients who are seen in the prehospital setting or present to the ED with symptoms suggestive of STEMI.”

Class I, Level of Evidence: B

Targeted History• Ascertain whether the patient has had prior episodes of

myocardial ischemia (stable or unstable angina, MI, CABG, or PCI)

• Focus on chest discomfort and associated symptoms• HTN?• DM?• Assess for possibility of aortic dissection• Assess risk of bleeding• Assess for clinical cerebrovascular disease (amaurosis fugax,

face/limb weakness or clumsiness, sensory loss, ataxia, vertigo

Class I, Level of Evidence: C

Physical Exam

Class ITo aid in the diagnosis and assessment of the extent, localization, and presence of complications of STEMI. (Level of Evidence: C)

A brief, focused neurologic exam in order to look for evidence of prior stroke or cognitive defects (before administering fibrinolytics) . (Level of Evidence: C)

ECGClass I

Should be done within 10 minutes of arrival. (Level of Evidence: C)

If the initial ECG is not diagnostic of STEMI but the clinical suspicion is high, serial ECG’s (5-10 minute intervals) or continuous 12 lead ST segment monitoring should be performed. (Level of Evidence: C)

With inferior STEMI, right sided ECG should be performed in order to look for ST elevation suggestive of RV infarct. (Level of Evidence: B)

Inferior Infarct

V6

V1 V2 V3V4

V5

Right Sided Leads

V1 (R)V2 (R)V3(R)

V6(R)

V4(R)

V5(R)

(R)

(R)

(R)

(R)

(R)

(R)

Inferior/RV Infarct

Laboratory Examinations

Class I

Cardiac-specific troponins should be used as the optimum biomarkers for the evaluation of patients with STEMI who have coexistent skeletal muscle injury. (Level of Evidence: C)

For patients with STEMI on the ECG and symptoms, reperfusion therapy should be initiated immediately and is not contingent on a biomarker assay. (Level of Evidence: C)

ECG

The 12 lead ECG is the center of the therapeutic decision pathway because of the strong evidence that ST segment elevation identifies patients who benefit from reperfusion therapy

Imaging

Class IPatients with STEMI should have a portable CXR, but this should not delay implementation of reperfusion therapy unless a contraindication, such as aortic dissection, is suspected. (Level of Evidence: C)

High quality pCXR, TTE and or TEE, and contrast chest CT or MRI should be used to differentiate STEMI from dissection in patients for whom this distinction is unclear. (Level of Evidence: B)

Initial Management; Oxygen

Class I

Supplemental O2 should be administered to patients with arterial oxygen desaturation (SaO2 less than 90%). (Level of Evidence: B)

Class IIa

It is reasonable to administer O2 to all patients with uncomplicated STEMI during the first 6 hours. (Level of Evidence: C)

Initial Management: Nitrates

Class I

Patients with ongoing ischemic discomfort should receive SL NTG (0.4mg) every 5 minutes for a total of 3 doses, after which an assessment should be made about the need for IV NTG. (Level of Evidence: C)

IV NTG is indicated for relief of ongoing ischemic discomfort, control of HTN, or management of pulmonary congestion. (Level of Evidence: C)

Initial Management: Nitrates

Class IIINitrates in all forms should be avoided in patients with an initial systolic blood pressure less than 90mmHg or greater than or equal to 30mmHg below baseline, in patients with marked bradycardia or tachycardia, and in patients with known or suspected RV infarction. In view of their marginal treatment benefits, nitrates should not be used if hypotension limits the administration of Beta Blockers

Initial Management: Analgesia

Class I

MSO4 (2-4mg IV with increments of 2-8mg IV repeated at 5-15 minute intervals) is the analgesic of choice for management of pain associated with STEMI. (Level of Evidence: C)

Initial Management: Aspirin

Class IAspirin should be chewed by patients who have not taken aspirin before presentation with STEMI. The initial dose should be 162mg (Level of Evidence: A) to 325 mg. (Level of Evidence: C)

Although some trials have used enteric-coated ASA for initial dosing, more rapid buccal absorption occurs with non-enteric coated formulations

Initial Management: Beta-Blockers

Class I

Oral BB therapy should be administered promptly to those patients without a contraindication, irrespective of concomitant fibrinolytic therapy or performance of primary PCI. (Level of Evidence: A)

Class IIa

It is reasonable to administer IV BB promptly to STEMI patients without contraindications, especially if a tachyarrhythmia or HTN is present. (Level of Evidence: B)

Reperfusion

Class I

All STEMI patients should undergo rapid evaluation for reperfusion and have a reperfusion strategy implemented promptly after contact with the medical system. (Level of Evidence: A)

Reperfusion

• For fibrinolytic therapy, goal is door to needle time of 30 minutes

• For PCI, goal is door to balloon inflation time of 90 minutes

• These goals may not be relevant for patients with an appropriate reason for delay such as uncertainty about the diagnosis, life threatening conditions (e.g., respiratory failure), or delays associated with patient’s informed failure to consent

Reperfusion

• These goals should not be understood as “ideal” times, but the rather the longest times that should be considered acceptable

• Systems that are able to achieve more rapid times should be encouraged

Selection of Reperfusion Strategy

• Several issues should be considered in selecting the type of reperfusion therapy– Time From Onset of Symptoms– Risk from STEMI– Risk of Bleeding– Time Required for Transport to a Skilled PCI

laboratory

Time From Onset of Symptoms• Time from onset of symptoms to fibrinolytic therapy is

an important predictor of MI size and patient outcome1

• The efficacy of fibrinolytic agents for lysing thrombus diminishes with time2

• Fibrinolytic therapy administered within the first 2 hours (especially the first hour) can occasionally abort MI and dramatically reduce mortality3,4

1Boersma, E., et al. Lancet, 1996;348:771-7752Zeymer et al. Am Heart J, 1999:137:34-383FTT Collaborative Group. Lancet, 1994;343:311-3224Weaver, WD et al. JAMA, 1993;270:1211-1216

Time From Onset of Symptoms• Conversely, the ability to produce a patent infarct artery is much

less dependent on symptom duration in patients undergoing PCI• Several reports claim no influence of time delay on mortality rates

when PCI is performed after 2-3 hours of symptom duration1,2 • However, after adjustment for baseline characteristics, time from

symptom onset to balloon inflation is significantly correlated with 1 year mortality in patients undergoing primary PCI for STEMI3

1FTT Collaborative Group. Lancet, 1994;343:311-3222Brodie et al. Am J Cardiol, 2001;88:1085-10903Williams, D. Circ, 2004;109:1806-1808

Risk From STEMI

• In patients at high risk for adverse outcome from STEMI, such as those with cardiogenic shock or high TIMI risk score1, compelling evidence exists that favors a PCI strategy

1Morrow et al. Circ. 2000;102:2031-2037

Risk of Bleeding

• If both types of reperfusion therapy are available, PCI is favored in patients at high risk for bleeding

• If PCI is not available, the risks and benefits of fibrinolysis must be weighed

Transport Time to PCI Lab

• For facilities that can offer PCI, the literature suggests that this approach is superior to fibrinolysis1

• The trials comparing fibrinolysis to PCI, however, were conducted prior to the advent of more recent PCI and pharmacologic therapies

• When a composite end point of death, nonfatal recurrent MI, or stroke is analyzed, much of the superiority of PCI is driven by the reduction of nonfatal recurrent MI2

1Magid et al. JAMA. 2000;284:3131-31382Boersma, E., et al. Lancet, 1996;348:771-775

PCI vs. Fibrinolysis; 4-6 Weeks

PCI vs. Fibrinolysis; Long Term

Reperfusion Strategy (cont.)

• As the time delay for performing PCI increases, the mortality benefit of PCI over fibrinolysis decreases1

• Compared with a fibrin-specific lytic agent, a PCI strategy may not reduce mortality when a delay greater than 60 minutes is anticipated vs. immediate lytic therapy

1Nallamothu et al. Am J. Cardiol. 2003;92:824-826

Reperfusion Strategy (cont.)

• Given the current literature, it is not possible to say definitively that a particular reperfusion approach is superior for all patients in all clinical settings at all times of day

• The main point is that some type of reperfusion therapy should be selected for all appropriate patients with suspected STEMI

• The appropriate and timely use of some reperfusion therapy is likely more important than the choice of therapy

Step II: Determine whether fibrinolysis or invasive strategy is preferred

Step I: Assess time and risk- Time since onset of symptoms- Risk from STEMI- Risk of fibrinolysis- Time required for transport to a skilled PCI lab

Fibrinolysis is generally preferred if

- Early presentation (3 hours or less and delay to invasive strategy) - Invasive strategy is not an option - Cath lab not available - Vascular access difficulties - Lack of access to a skilled lab - Delay to invasive strategy

Invasive strategy is generally preferred if - Skilled PCI lab available with surgical backup - High risk from STEMI - Cardiogenic shock - Killip class > or = to 3 - Contraindications to fibrinolysis including increased risk of bleeding and ICH - Late presentation - Symptom onset more than 3 hours - Diagnosis of STEMI is in doubt

Fibrinolytic TherapyClass I

STEMI patients presenting to a facility without the capacity for expert, prompt intervention (primary PCI with 90 minutes of first medical contact) should undergo fibrinolytic therapy. (Level of Evidence: A)

In the absence of contraindications, fibrinolytic therapy should be administered to STEMI patients with symptom onset within the prior 12 hours and ST elevation greater than 0.1mV in at least 2 contiguous precordial leads or at least 2 adjacent limb leads. (Level of Evidence: A)

In the absence of contraindications, fibrinolytic therapy should be administered to patients with symptom onset within the prior 12 hours and new or presumably new LBBB. (Level of Evidence: A)

Fibrinolytic Therapy

Class IIa

In the absence of contraindications, it is reasonable to administer fibrinolytic therapy to STEMI patients with symptom onset within the prior 12 hours and ECG findings consistent with true posterior MI. (Level of Evidence: C)

In the absence of contraindications, it is reasonable to administer fibrinolytic therapy to patients with symptoms of STEMI beginning within the prior 12-24 hours who have continuing ischemic symptoms and ST elevation greater than 0.1mV in at least 2 contiguous precordial leads or at least 2 adjacent limb leads. (Level of Evidence: B)

True Posterior MI

V6

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True Posterior MI

V6

V1 V2 V3V4

V5

V9 V8V7

True Posterior MI

Fibrinolytic Therapy

Class IIIFibrinolytic therapy should not be administered to asymptomatic patients whose initial symptoms of STEMI began more than 24 hours earlier. (Level of Evidence: C)

Fibrinolytic therapy should not be administered to patients whose ECG shows only ST segment depression unless true posterior MI is suspected. (Level of Evidence: A)

Contraindications and Cautions for Fibrinolysis use in STEMI

Absolute Contraindications - Any prior ICH - Known structural cerebral vascular lesion (e.g., AVM) - Known malignant intracranial neoplasm (1o or 2o) - Ischemic stroke within 3 months except acute ischemic stroke within 3 hours - Suspected aortic dissection - Active bleeding or bleeding diathesis (except menses) - Significant closed head or facial trauma within 3 months

Relative Contraindications - History of chronic, severe, poorly controlled HTN - Severe, uncontrolled HTN on presentation (SBP>180, DBP>110) - Hx of prior ischemic stroke >3 months, dementia, or known IC pathology not listed in contraindications - Traumatic or prolonged CPR (>10 min) or major surgery (<3 weeks) - Recent internal bleeding (2-4 weeks) - Noncompressible vascular punctures - For Streptokinase/Anistreplase: prior exposure (>5 days) or prior allergic rxn - Pregnancy - Active peptic ulcer - Current use of anticoagulants; the higher the INR, the higher the risk

Percutaneous Coronary Intervention

Class I

If immediately available, primary PCI should be performed in patients with STEMI (including posterior MI), or in patients with new LBBB who can undergo PCI of the infarct artery within 12 hours of onset of symptoms. (Level of evidence: A)

PCI must be performed in a timely fashion (door balloon time 90 minutes) by persons skilled in the procedure (greater than 75/year). (Level of evidence: A)

Percutaneous Coronary Intervention

Class IPrimary PCI should be performed for patients younger than 75 years with STEMI or LBBB who develop shock within 36 hours of MI and are suitable for revascularization that can be performed within 18 hours of shock. (Level of Evidence: A)

Primary PCI should be performed in patients with severe CHF and/or pulmonary edema (Killip class III) and onset of symptoms within 12 hours. Door balloon should be within 90 minutes. (Level of Evidence: B)

Percutaneous Coronary Intervention

Class IIaPrimary PCI is reasonable for patients >75 yrs who develop shock within 36 hours of MI and are suitable for revascularization that can be performed within 18 hours of shock. (Level of Evidence: B)

It is reasonable to perform primary PCI for patients with onset of symptoms in prior 12-24 hours and severe CHF (Level of Evidence: C), hemodynamic or electrical instability (Level of Evidence: C), or persistent ischemic symptoms (Level of Evidence: C)

Percutaneous Coronary Intervention

Class IIIPCI should not be performed in a non-infarct artery at the time of PCI in patients without hemodynamic compromise. (Level of Evidence: C)

Primary PCI should not be performed in asymptomatic patients more than 12 hours after onset of STEMI if they are hemodynamically and electrically stable. (Level of Evidence: C)