ECG to be taken from the start of thrombolysis or from the end of thro

ECG to be taken from the start of thrombolysis or from the end of thrombolysis in STEMI

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ECG timing after thrombolysis STEMI reperfusion assessment 90 minutes

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ECG Timing After Thrombolysis in STEMI

The Answer: From the START of Thrombolysis

The ECG is assessed 60-90 minutes after the START of thrombolytic therapy - not from the end of administration. This is the internationally accepted standard across AHA/ACC, ESC, and Australian Heart Foundation guidelines.

The rationale is straightforward: the clock starts when the drug begins working (i.e., when infusion starts), and you want to assess whether the vessel has reopened at a clinically meaningful time point. Waiting until after the infusion ends would shift the assessment window and potentially delay identification of failed reperfusion.

What the ECG Assesses at 60-90 Minutes

The key marker is ST-segment resolution. The criterion for successful reperfusion is:

≥50% reduction in ST-segment elevation in the lead with the highest initial ST elevation, measured at 60-90 minutes from the start of thrombolysis

Additional signs of successful reperfusion include:

Relief of chest pain
Accelerated idioventricular rhythm (reperfusion arrhythmia)

Practical Protocol (Alberta Health Services / Standard)

ECGs are taken serially at 30, 60, and 90 minutes after the START of fibrinolytic administration - or earlier if symptoms worsen or ST elevation increases.

Failed Reperfusion Criteria (Rescue PCI Trigger)

Patients should be transferred immediately for rescue PCI if any of the following persist at 60-90 minutes post-thrombolysis start:

Ongoing or worsening chest pain
<50% ST-segment resolution (persistent/worsening ST elevation)
Hemodynamic instability or heart failure
Unstable arrhythmias

(Washington Manual of Medical Therapeutics, p. 156)

Summary Table

Parameter	Detail
ECG timing reference	From START of thrombolysis
Assessment time point	60-90 minutes post-start
Target for success	≥50% ST reduction
If target not met	Rescue PCI indicated
Serial ECG protocol	At 30, 60, and 90 minutes

Key takeaway: The 90-minute ECG is timed from the start of thrombolytic infusion. This is the window in which a successfully lysed thrombus should have restored flow, and the ST changes should reflect that. If the ECG at 90 minutes (from start) does not show ≥50% ST resolution, failed fibrinolysis is declared and urgent rescue PCI is the next step.

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