STEMI-70

Published: June 1st, 2016

Category: STEMI

Pre-hospital ECG

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Emergency Department ECG

ECG1

Right Side ECG

ECG2

  • Patient arrived bradycardic and hypotension
  • Complete AV block on ECG
  • Transcutaneous pacing started while awaiting cath
  • Patient converted to sinus tach while transvenous pacer being placed

Cardiac Cath Report

1. LMCA: Large, long, widely patent, gives rise to the LAD and LCX.

2. LAD: Normal caliber, transapical, mid LAD 40%, small D1, D2, D3 are patent.

3. LCX: Normal caliber, nondominant, OMB1 is normal caliber and patent, small AV groove LCX is patent.

4. RCA: Large, dominant, mid 95% high grade stenosis with thrombus, patent right PDA and right PL branches.

 

Teaching

Complete Heart Block

  • Complete absence of AV conduction
  • Perfusing rhythm is maintained by a junctional or ventricular escape rhythm
  • Mechanism
    • It may be due to progressive fatigue of AV nodal cells as per Mobitz I (e.g. secondary to increased vagal tone in the acute phase of an inferior MI).
    • Alternatively, it may be due to sudden onset of complete conduction failure throughout the His-Purkinje system, as per Mobitz II (e.g. secondary to septal infarction in acute anterior MI).
  • Causes
    • Inferior MI
    • AV nodal blocking drugs
    • Idiopathic degeneration of conduction system
  • Complete Heart Block Complicating ST-Segment Elevation Myocardial Infarction : Temporal Trends and Association With In-Hospital Outcomes [JACC 2015;1(6):529-38]
    •  2,273,853 patients with STEMI, 49,882 (2.2%) had CHB
    •  STEMI patients with CHB had higher in-hospital mortality than those without CHB
    • The higher mortality associated with CHB was independent of the location of STEMI
    • The incidence of CHB was higher in patients with inferior STEMI compared with those with anterior STEMI

CHB

CHB2

Inferior MI

  • 40-50% of all myocardial infarctions.
  • more favorable prognosis than anterior myocardial infarction
  • Up to 40% of patients with an inferior STEMI will have a concomitant right ventricular infarction. These patients may develop severe hypotension in response to nitrates and generally have a worse prognosis.
    • Confirmed with Right sided ECG, Elevation in V4R
  • Up to 20% of patients with inferior STEMI will develop significant bradycardia due to second- or third-degree AV block. These patients have an increased in-hospital mortality (>20%).
  • ECG findings
    • ST elevation in leads II, III and aVF
    • Reciprocal ST depression in aVL (± lead I)
    • RCA (80%): Elevation in III > II, Reciprocal depression in I
    • LCx (20%): Elevation in III = II, No reciprocal depression in I