This study looked at how often the out-of-hospital and emergency department ECG diagnostic classification changed in adult patients with return of spontaneous circulation (ROSC) from out-of-hospital cardiac arrest (OHCA).
The ST segment morphology post cardiac arrest may change for various reasons including:
- no/low flow states
- hypoxia
- acidosis
- defibrillation
- adrenaline administration
- vasospasm
- ischaemia due to underlying coronary artery disease.
In this study, nearly half of the ECGs changed classification from initial out of hospital ECG to the emergency department ECG. Of these, the majority (80%) changed to a less ischaemic pattern. Serial ECGs and the timing of angiography become important. Refer also to the PEACE Trial (1).
The Study
Aufderheide T.T., et al. Change in out-of-hospital 12-lead ECG diagnostic classification following resuscitation from cardiac arrest. Resuscitation 169 (2021) 45-52.
What They Did
This was a retrospective case series evaluation of patients in one US hospital.
The inclusion criteria were:
- > 18 years old
- ROSC following a presumed cardiac cause of cardiac arrest.
- At least one ECG recorded in both the pre-hospital setting and in the emergency department
ECGs were assessed by emergency physicians and a cardiologist and were classified as either:
- STEMI
- Ischaemic or
- Non-Ischaemic
The time from ROSC to ECGs being performed was measured at two time points ie., < or > than 7 minutes, for the purpose of evaluating any change in ECG classification.
What They Found
N= 176
- 504 ECGs were used in the study:
- 235 (46%) were out-of-hospital ECGs
- 272 (54%) were emergency department ECGs.
ECG classifications vs emergency department classifications were as follows:
- STEMI: There was a significant difference in the change in classification.
- 27.8% vs 11.9%
- Ischaemic
- 34.7% vs 61.4%
- Non-ischaemic
- 37.5% vs 61.4%
48.9% of patients changed classification from out-of-hospital to the emergency department, with 80% of these changing to a less ischaemic ECG.
27.8% of patients had an initial out-of-hospital STEMI diagnosis on ECG. 67.3% of these patients changed to a non- STEMI classification.
How long did it take for the change in classification to occur?
Of the 52.2% of patients where time to ECG was recorded as < 7 minutes post ROSC, 51.8% had a classification change
Of those 47.8% with times of > 7 minutes from ROSC to ECG, 47.4% had a classification change.
The Verdict
In this study nearly half of the ECGs changed classification from initial out of hospital ECG to the emergency department ECG. Of these, the majority (80%) changed to a less ischaemic pattern.
This is a single center, retrospective case series, with potential selection bias, issues with record availability and no control over who received an ECG. It simply looks at ECG findings and does not correlate them with coronary angiography. It also doesn’t tell us anything about the rate of change of ECGs after 7 minutes. Is there a point past which, no changes occur? Is there an optimal point at which we can make a call for sending the patient to the cath lab? See the PEACE Trial (1).
What this means to me is that we should look at all ECGs and certainly perform ECGs early. However given than nearly half of the ECGs changed to a less ischaemic classification, we should consult with and wait perhaps for 20-30 minutes before making a call. It also tells me that we should be performing serial ECGs in these post ROSC from cardiac presumed causes of cardiac arrest, as 20% of the patients in this study progressed from a less ischaemic to a more ischaemic ECG.
References
- Baldi E., et al. Association of Timing of Electrocardiogram Acquisition After Return of Spontaneous Circulation With Coronary Angiography Findings in Patients With Out-of-Hospital Cardiac Arrest. JAMA Network Open. 2021;4(1):e2032875.doi:10.1001/jamanetworkopen.2020.32875
This Literature Review first appeared on EM Mastery.
