STEMI

• Identify patients with STEMI as soon as possible for immediate revascularization.

• Treatment of choice: PCI within 90 minutes of first medical contact (FMC).

• Consider intravenous fibrinolytics if:

  • PCI cannot be performed within 120 minutes

  • AND there are no contraindications to fibrinolytics for STEMI

Avoid excluding a diagnosis of STEMI based on a single ECG as findings can change over time and with symptom fluctuation.

• Definition: significant ST elevation in two contiguous leads

• Additional considerations

  • ECG findings may change over time

  • Hyperacute T waves can be present without ST elevations in the very early stages of ischemia.

  • If inferior myocardial infarction is suspected, investigate for signs of right ventricular involvement

• Acute stage: myocardial damage ongoing

  • Hyperacute T waves (peaked T wave)

  • ST elevations in two contiguous leads with reciprocal ST depressions

• Intermediate stage: myocardial necrosis present

  • Absence of R wave

  • T-wave inversions

  • Pathological Q waves

    • Duration ≥ 0.04 seconds

    • Amplitude ≥ ¼ of the R wave or ≥ 0.1 mV

    • Any Q wave in leads V1–3

• Chronic stage: permanent scarring

  • Persistent, broad, and deep Q waves

  • Often incomplete recovery of R waves

  • Permanent T-wave inversion is possible.

The sequence of ECG changes over several hours to days: hyperacute T wave → ST elevation → pathological Q wave → T-wave inversion → ST normalization → T-wave normalization

• A set of ECG criteria that can help identify STEMI in patients with LBBB and high clinical suspicion of ACS.

• Acute STEMI is likely if any of the following are present:

  • Concordant ST elevation of ≥ 1 mm in any lead

  • Concordant ST depression of ≥ 1 mm in any of leads V1–V3

  • Discordant ST elevation ≥ 1 mm and ≥ 25% of preceding S wave

Positive modified Sgarbossa criteria can help identify STEMI in symptomatic patients with LBBB for whom ST-segment assessment is difficult.

PCI for STEMI

• Indication: preferred method of revascularization in patients suspected of having STEMI

• Procedure: coronary angiography with PCI, i.e., balloon dilatation with stent implantation

• First medical contact (FMC) to PCI time

  • Ideally ≤ 90 minutes.

  • Should not exceed 120 minutes

• Indications (in STEMI and STEMI equivalents, if all of the following apply):

  • PCI cannot be performed ≤ 120 minutes after FMC.

  • Symptom onset

    • ≤ 12 hours

    • OR 12–24 hours with clinical signs of ongoing ischemia (PCI is even more preferable in this context)

  • No contraindications to fibrinolysis present

• Timing: within < 30 minutes of patient arrival at the hospital [1]

• Contraindications

  • If > 24 hours after symptom onset

• Regimens (one of the following)

  • Tenecteplase

  • Alteplase

  • Reteplase

  • Streptokinase

Initiate therapy without delaying revascularization.