A 57-year-old man was brought in by ambulance with 1 hour of left shoulder pain, nausea and feeling faint.
He had a history of obstructive sleep apnoea and recurrent low back pain.
Paramedics had given aspirin and clopidogrel, obtained IV access and called us saying probable inferior STEMI.
He goes into a resus bay and the team pounce on him: monitoring, ECG, a second IV line, bloods including a troponin, a very focused history and examination.
He is pale but his obs are normal.
These was his first ECG in ED.
It shows an inferior STEMI. Note the reciprocal ST depression in aVL which helps to support the diagnosis.
See STEMI criteria.
We don’t have PCI so he needed thrombolysis. Generally we will thrombolyse anyone who meets ECG criteria, has had pain for less than 12 hours and doesn’t have contraindications.
As always, if you are alone at night (or any other time) trying to make this big decision, scan and email, or text a photo of the ECG to someone else for a second opinion.
Contraindications to Thrombolysis
We quickly checked that he didn’t have any contraindications to thrombolysis. You can use a check list for this:
|History of any intracranial hemorrhage|
|History of ischemic stroke within the preceding three months, with the important exception of acute ischemic stroke seen within three hours, which may be treated with thrombolytic therapy|
|Presence of a cerebral vascular malformation or a primary or metastatic intracranial malignancy|
|Symptoms or signs suggestive of an aortic dissection|
|A bleeding diathesis or active bleeding, with the exception of menses; thrombolytic therapy may increase the risk of moderate bleeding, which is offset by the benefits of thrombolysis|
|Significant closed-head or facial trauma within the preceding three months|
|History of chronic, severe, poorly controlled hypertension or uncontrolled hypertension at presentiaton (blood pressure >180 mmHg systolic and/or >110 mmHg diastolic; severe hypertension at presentation can be an absolute contraindication in patients at low risk)|
|History of ischemic stroke more than three months previously|
|Any known intracranial disease that is not an absolute contraindication|
|Traumatic or prolonged (>10 min) cardiopulmonary resuscitation|
|Major surgery within the preceding three weeks|
|Internal bleeding within the preceding two to four weeks or an active peptic ulcer|
|Noncompressible vascular punctures|
|Current warfarin therapy – the risk of bleeding increases as the INR increases|
|For streptokinase or anistreplase – a prior exposure (more than five days previously) or allergic reaction to these drugs|
So key screening questions to ask your patient: Are you prone to excessive bleeding, have you ever had anything unusual happen to your brain like a stroke or head injury, does your pain radiate to your back, is it tearing, was it most severe at onset, have you been in hospital in the last 3 months, what medications are you on, could you be pregnant?
Check their blood pressure, check both radial pulses, listen for aortic regurgitation from a thoracic aortic dissection
Discuss the risks and benefits with the patient.
Benefit: one life saved for every 43 people treated within 6 hours of onset of pain (there are likely to be more who have no or reduced heart failure or angina due to treatment).
Harm: One in 250 recipients will have a haemorrhagic stroke – usually fatal. 2 of the patients I have thrombolysed have bled into their brains and died. It isn’t pleasant. There is also risk of other serious bleeding. If the patient has any of the relative contraindications their risk of bleeding may be highter.
We usually use tenectoplase. Some recommend streptokinase for the elderly as it is associated with a lower rate of intracranial bleeding.
Inject the 10 ml of water from the syringe into the bottle with the powder then mix.
Tip the bottle and syringe upside down and draw out the required volume of the mixture. The weight-adjusted dose is on the syringe. Our patient was over 90kg so he got the full 10ml = 50mg.
|Weight (kg)||tenecteplase (IU)||tenecteplase (mg)||Volume of reconstituted solution (mL)|
|60 to < 70||7,000||35||7|
|70 to < 80||8,000||40||8|
|80 to < 90||9,000||45||9|
|90 and up||10,000||50||10|
Give it as an IV push over 5 seconds
Give aspirin and clopidogrel if not already given. Dose of clopidogrel with thrombolysis is controversial. We currently use 300mg.
Give 30mg IV enoxaparin (omit if > 75 years old or known GFR < 30). Then 1mg/kg SC enoxaparin (0.75mg/kg if patient over 75, max 75mg).
Then we gave him small boluses of fentanyl. I’m a little cautious with the opioids with inferior ventricular infarcts. They might have right ventricular infartion as well (see below). I don’t want to venodilate the patient too much. That would decrease his right ventricular preload and therefore his left ventricular preload.
After 40mcg of fentanyl he was painfree and back to a normal colour. About 15 minutes post tenectoplase his inferior ST elevation had reduced to ~ 1mm.
If his pain persisted and 60-90 minutes post tenectoplase his ST elevation was still > half of what it had been at its largest this would count as failed thrombolysis. Patients with failed thrombolysis are candidates for urgent transfer for PCI. Some argue that all STEMIs in peripheral hospitals should be thrombolysed and flown urgently to a PCI capable centre so that they can receive PCI if thrombolysis fails. This is not the practice in our region.
Door to Needle Time
I was a little disappointed our door to needle time was 5 minutes. We can do better, eg we could have had the tenectoplase at the bedside before the patient arrived.
For interest, after thrombolysis, we also did a right-sided and posterior ECG.
His right-sided ECG (V4, V5 and V6 put on to the R side of the chest) showed ST elevation in V4R and V5R showing right ventricular infarction
The posterior ECG didn’t show any posterior ST elevation. So this is an inferior and right ventricular STEMI.
Delayed ST Elevation
One last point: If your patient has chest pain and a normal ECG, then develops ST elevation in front of you: thrombolyse, no matter how long they have had the pain.
Thrombolysis contraindications from UpToDate http://www.uptodate.com/contents/image?imageKey=CARD/68784&source=graphics_search&rank=0&search=thrombolysis
Tenectoplase dose http://www.medsafe.govt.nz/profs/datasheet/m/Metalyseinj.pdf
Risks and benefits of thrombolysis from the NNT http://www.thennt.com/nnt/thrombolytics-for-major-heart-attack/
Whanganui Hospital ACS Guideline.
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