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Sunday, October 14, 2007

Q&A based on Malaysian MOH CPG Management of Acute STEMI


I have compiled a series of Q&A notes based on the latest CPG on STEMI. If there is any mistake, please email me at cksheng74@yahoo.com. Cheers,
K.S. Chew



Management of Acute Myocardial Infarction



  1. In some cases of early MI, the ECG can be normal or equivocal. In such cases, serial ECG is advocated. What is the time interval recommended for the repeat ECG?

  1. Which cardiac biomarkers are most specific for MI?

  1. For the diagnosis of STEMI, what is the value of CK-MB should be as compared to its normal range?

  1. Why is CKMB useful for diagnosis of reinfarction?

  1. In a patient with a known diagnosis of coronary heart disease, how often can sublingual GTN be given while en route to emergency department?

  1. What is the time interval for

    1. Door to ECG?
    2. Door to needle?
    3. Door to balloon?

  1. Generally which is better – primary PCI or fibrinolytic therapy?

  1. So, how effective is fibrinolytic therapy?

  1. How would you decide which therapy (primary PCI or fibrinolytic therapy) to be given? What are factors of consideration?

  1. In people considered high risk, primary PCI is generally preferred. Who are considered high risk?

  1. In selected groups of people presented very late (>12 hours), reperfusion therapy would still be beneficial. Who are they?

  1. What are the available choices of fibrinolytic therapy?

  1. What are the regimens of giving streptokinase?

  1. Can fibrinolytic therapy still be given in a patient with hypotension (systolic BP<90>

  1. Can fibrinolytic therapy be given in NSTEMI?

  1. What are the definitions of

1. Primary PCI

2. Facilitated PCI

3. Delayed PCI

4. Rescue PCI

5. Emergency PCI

  1. How long should complete bed rest be advocated in a patient with acute myocardial infarction in the cardiac care unit?

  1. What is concomitant therapy that should be given in ED and CCU?

  1. What are the roles of nitrates in the management of acute myocardial infarction?

  1. What are the contraindications of giving nitrates?

  1. What are the differences between unfractionated heparin and low molecular weight heparin?

  1. What is the different between early ventricular fibrillation and late ventricular fibrillation that complicates AMI?

  1. Does all 2nd degree Mobitz 2 and 3rd degree heart block that complicates AMI require treatment?

  1. What is the treatment modality for AMI patient complicated with cardiogenic shock?

  1. How do you suspect the diagnosis of mechanical complications in AMI?

  1. What is clinical triad of right ventricular infarction?

  1. Which lead would you look for in the diagnosis of right ventricular infarction?

  1. How would you manage a patient complicated with right ventricular infarction? What would you suspect if the patient does not respond to the standard measures?

  1. How would you suspect the diagnosis of reinfarction?

  1. What is post infarct angina?

  1. List the medications that have been shown to reduce the incidence of sudden death.

  1. What should be the target

    1. blood pressure
    2. lipids level
    3. glycemic control in a post MI patient?

  1. What are medications that should be continued on in a post MI patient as secondary prevention?

  1. How long should a patient with AMI be hospitalized?


Management of Acute Myocardial Infarction

  1. At least 15 min. Comparison with previous ECGs may also be useful.

  1. Cardiac troponins and CKMB. However they only start to rise after around 3 hours. So, early measurement may lead to a false negative results. Free fatty acid binding proteins and myoglobin rise earlier (around 1.5 hours)

  1. At least twice that of upper limit of normal.

  1. CK-MB rises and falls early (falls by 48 hours; CK falls by 72 hours). Persistently elevated values of CK-MB are almost never due to myocardial necrosis. Therefore CK-MB is useful for diagnosis of reinfarction. By contrast, troponins fall only by 7 – 14 days (Troponin I remain elevated up to 7 – 10 days and Troponin T remains elevated up to 10 – 14 days)

  1. That depends whether the pain is suggestive of STEMI. If the patient is severe, patient should take one tab of S/L GTN and be rapidly transported to hospital. If pain is not severe, take one tablet of GTN and repeat every 5 minutes, for a maximum of 3 tablets. If pain still persist after three tablets, patient should go to hospital.

  1. Time interval for
    1. Door to ECG? Within 10 minutes
    2. Door to needle? Within 30 minutes
    3. Door to balloon? Within 90 minutes
    4. Therefore the PCI time delay (which is (door to balloon) – (door to needle) time difference should be less than 60 minutes

  1. Most studies indicate that primary PCI is superior to fibrinolytic therapy

  1. Fibrinolytic therapy has been shown to be effective when given early. If given within 1 hour from time of osnet of symptoms, able to reduce mortality by up to 50%.

  1. Depends of

Time from onset of symptoms

Facilities available

Transport time

More than 12 hours

Generally both not given especially if patient already stable and asymptomatic except for certain groups of patients (see next question).

Less than 12 hours

If more than 3 hours but less than 12 hours

PPCI is preferred. But if can’t transfer within 2 hours, then fibrinolytic

If less than 3 hours

PPPCI and fibrinolytic shown to be equally effective

Unless if PCI facilities nearby (acceptable PCI time delay)

If patients is considred high risk, then PPCI preferred (see next question)

  1. High risks include:

- large infarcts

- anterior infarcts

- cardiogenic shock

- elderly patient

- post revascularization (post PCI and post CABG)

- post infarct angina

  1. Reperfusion therapy would still be beneficial even though patient presented very late (> 12 hours), if
    1. Still with persistent symptoms
    2. Hemodynamic instability
    3. Electrical instability

  1. Fibrinolytic can be divided into

I Fibrin selective

Ia Older generation

Alteplase

Higher achievement of reperfusion

But higher rate of reocclusion also

So, need heparin (post administration of ) for at least 48 hours (Level of evidence I, Grades of recommendation A; as compared to usage of heparin in post streptokinase, Level of evidence of IIa, class of recommendation B)

Ib Newer second generation

Tenecteplase

As efficacious as alteplase but

a. Slightly lower bleeding rate

b. Easier to administer (main advantage) – can give as single or double boluses

Again, need heparin for at least 48 hours

Non fibrin selective

Classically streptokinase

Less efficacious as compared with fibrin selective

Lower risk of intracranial hemorrhage

Overall, reduction of mortality is less than fibrin selective type

Antigenic, therefore less effective if given again after 5 days of the first administration in cases of reinfarction

  1. Streptokinase can be given as
    1. 1.5 mega units in 100 cc normal saline or D5% over 1 hour
    2. 1.5 mega units over 20 minutes (faster infusion)
    3. 0.75 mega units (half of it) as a bolus then the rest over the next 50 minutes IF there is no clinical reperfusion

  1. Can. But support with inotrope prior to administration.

  1. No. May even be detrimental if given in NSTEMI

  1. Definitions of

Primary PCI – PCI performed promptly when patient having symptoms

Facilitated PCI – Combining PCI and fibrinolytic to achieve reperfusion rates

Delayed PCI – PCI after >72 hours post fibrinolytic – not for routine

Rescue PCI – PCI when failed fibrinolytics (no clinical evidence of reperfusion)

Emergency PCI – PCI when patient in cardiogenic shock

  1. At least 12 hours; stool softeners is encouraged also because Valsalva maneuver has been shown to precipitate dangerous hemodynamic and ECG changes particularly in the youngs.

  1. In ED – MONA Morphine, Oxygen, Nitrates, Aspirin (+/- clopidogrel); in CCU, MONA + ABC – ACEI, Beta Blocker, Clopidogrel

  1. Nitrates actually has not been shown to improve survival but is used for:

- continuing chest pain

- heart failure

- hypertension

  1. Beware of nitrates in

- SBP <>

- RV infarction

- History of PDEI usage (like Viagra)

  1. LMWH actually was associated with better clinical outcomes as compared to UFH following fibrinolytics; however higher risk of bleeding; therefore, in patients over 75 years old and with renal impairment (serum creatinine > 200 μmol/l) – UFH is preferred.

  1. Early VF (<48>

  1. No – if hemodynamically stable

  1. Emergency PCI

  1. Sudden clinical deterioration and new onset murmurs

  1. Hypotension, clear lung base, elevated JVP

  1. rV4 – look for ST elevation – however this maybe transient, resolving by 8 – 10 hours

  1. Re-fill the RV (optimize with IV fluid) and inotropes. If doesn’t respond, think of both LV and RV dysfunctions

  1. Recurrence of chest pain; recurrence of STE at least 0.1 mV in contiguous leads; re-elevation of CKMB

  1. Early recurrent angina after successful reperfusion.

  1. ACEI, Aldosterone antagonists, eplerenone, B-blocker, statins

  1. Target

    1. blood pressure <130/80
    2. lipids level LDL<2.0>
    3. glycemic control in a post MI patient: FBS <6.0>

  1. Medications

Aspirin – indefinitely

Clopidogrel – at least 1 month

B-blocker – indefinitely

ACEI – indefinitely

Statins – indefinitely

Warfarin- if persistent AF; for LV thombus 3 – 6/12 of warfarin

  1. If asymptomatic and uncomplicated, can discharge after 3-5 days.

Reference:

Clinical Practice Guidelines on Management of Acute ST Segment Elevation Myocardial Infarction (STEMI) 2007. Ministry of Health, Malaysia, National Heart Association Malaysia and Academy of Medicine, Malaysia; 2007.

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