EKG Considerations

Criteria per 2013 AHA Guidelines:
- ST elevation in 2 contiguous leads of ≥ 1 mm
Except for leads V2 and V3 where STE must be taller:
≥ 2 mm in men
≥ 1.5 mm in women
- ST depression ≥ 2 mm in anterior leads c/w a posterior STEMI
- Multi-lead depressions with ST elevation in aVR c/w L main or LAD lesion
- LBBB with +Sgarbossa criteria (concordant STE, concordant STD V1-V3, or > 5 mm discordant STE)
- Maximal onset symptoms in 12-24 hours

Quick HPI & Exam
[ ] "Not dissecting:" Cocaine? Ripping/tearing, max at onset?
[ ] "Not pericarditis:" Young? Positional pain? Recent viral illness?
[ ] Eligible for a cath?
- Not CMO; never been told can't be cath'd (i.e., no known multivessel disease unamenable to cath)
[ ] Phys Ex: heart sounds, lung sounds, pulses x 4, rectal exam
- Rub with pericarditis, DEM with dissection. Consider bedside US of heart & aorta

Lytics, Cath lab or CABG?
[ ] For STEMI, PCI within 90 mins, or fibrinolytics within 30 mins
- If PCI will be delayed 120 mins, give 'lytics prior to PCI
- tPA (alteplase) 15 mg IV bolus, then 0.75 mg/kg (up to 50 mg) over 30 minutes, then 0.5 mg/kg (up to 35 mg) over 60 minutes. (Max total dose 100 mg)
- contras: any h/o ICH, malignancy or vascular malformation; ischemic CVA, severe head trauma in past 3 months
- post-reperfusion, common to see PVCs, non-sustained VT, and accelerated idioventricular rhythms. Do not require treatment
[ ] If EKG is not STEMI-equivalent, still benefit from emergent caths for:
- Objective evidence of ACS (+ troponin and/or dynamic EKG changes) with pain uncontrolled by nitro
[ ] Think cardiac surgery when:
- STE in aVR with other ischemic findings (e.g. diffuse STDs) c/f left main dz
- STE in aVR and aVL, or aVR and V1, highly specific for left main dz
- New severe murmur c/w valve rupture
- Aortic dissection with STEMI (i.e. dissecting down RCA)

Adjunctive care
[ ] ASA 325
[ ] heparin 60 U/kg bolus (max 5,000 U), then 12 U/kg/h (maximum 1,000 U/h) gtt, titrate to aPTT 50-75
- If h/o HIT: Bivalrudin 0.25 mg/kg IV bolus, then 0.5 mg/kg/hr gtt for 12 hours
- Do not use Fondaparinux as sole anti-coagulation, a/w catheter thrombosis, Class III Harm

[ ] A PGY12 platelet inhibitor "as early as possible or at time of primary PCI"
- Plavix 600 mg PO (may defer if c/f need for CABG)
- Or Prasugrel 60 mg, or Ticagrelor 180 mg

ST Elevations Diff Dx
[ ] compare to T-P segment to judge
[ ] BER: usually anterior, smile-face contour, fish-hook contour in V4, often with LVH, does not evolve (rpt EKG)
[ ] BBB
[ ] pericarditis: PR dep with PR elev in aVR
[ ] LV aneurysm: STE in V1-V2 with Qs from old anterior MI

ST Depressions Diff Dx
[ ] Posterior STEMI: STD in V1-V3, +/- tall Rs in those leads
[ ] reciprocal changes / ischemia: PLANAR STD = ischemia
[ ] subendocardial infarct
[ ] Dig effect
[ ] LVH with repol abnormality (“strain”): tall R waves with downsloping STD and asymmetric inverted Ts, worse with tachycardia / HTN

Flipped Ts
[ ] TWI is normal in V1, acceptable in V2 and III – pathology anywhere else:
- ischemia, CNS bleed Ts, PE, Wellens
[ ] Normal T is < 5 mm in limbs < 10 mm precordial; +; asymmetrical
[ ] Bad T is SYMMETRIC, large or inverted
- TWI in aVL a/w significant LAD lesion, also an early reciprocal change in acute inferior MI.

Wide QRS or BBB
[ ] BBB, hyperK+, paced, WPW, tox/med (TCA, Dig, etc), ventricular rhythm
[ ] “BBB man”: RBBB + in V1, – in V6; LBBB + in V6, – in V1
- in LBBB, ST always discordant (or isoelectric) to terminal QRS
- in RBBB only always discordant (or isoelectric) for V1-V3
[ ] If LBBB: check Sgarbossa criteria (only need 1 lead):
- ST segs should be discordant to QRS
- If > 5 mm discordance however that’s too much: specific for MI
- If > 1 mm concordance, also specific for MI:
(>1 mm STE in any lead or STD in V1,2,3)
[ ] If RBBB: should never see STE.
- Since normal STD V1-V3 can’t see posterior MI, so check posterior EKG in RBBB + CP.
- RBBB or RBBish plus STE V1 V2 = Brugada (cove or saddle)

[ ] TWI in V1-V4 or biphasic Ts precordial esp V2 and V3
[ ] Classically seen in pain-free EKG so get serials
[ ] Trop not elevated
- No stress test!

“Not Sinus Rhythm”
[ ] In SR: P up in II, inverted in aVR. If not so: limb lead reversal
[ ] Regular? (Irregular = AFib)
[ ] QRS Narrow? (Narrow regular = ST (can’t see P waves > 150), SVT, Aflutter)
- Aflutter best in II and V-1, unmask with Adenosine
- ST unmask with fever control, fluids
[ ] QRS Wide? VTach (or aberrancy or BBB but tx VT)
[ ] Rate slow? Jx’al, hyperK+, Dig toxic

Q waves
[ ] Normal in lateral (and sometimes inferior) leads if small (“septal Qs”; look for analogous small + deflections in V1 V2)
[ ] Qs in V1 V2 are pathological: LBBB vs septal MI
[ ] Deep, narrow Qs in lateral leads c/f HOCM esp if high voltage otherwise

Long QTc
[ ] Low ‘lytes (Ca Mag K)
[ ] Usually 2/2 large T wave, but if 2/2 prolonged S-T segment: HypoCa++
[ ] Replete calcium, magnesium up front

Inferior STEMI:
- bradycardia = vagal event (diaphragmatic irritation), responds to Atropine
- hypotension = preload, IVF responsive

Anterior STEMI:
- bradycardia = conduction system ischemia, no Atropine
- hypotension = pump failure, IVF won’t help
- brady + hypotension = 80% mortality
- STE in aVR + aVL/V1: Left main STEMI, only hope is cath lab vs CABG, lytics useless
- Only applies when symptomatic and other ischemic changes; doesn’t apply in SVTs

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