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Risk Score for Early Prediction of Neurological Outcome After Out-of-Hospital Cardiac Arrest
Quick Takes
- A MIRACLE2 score of ≥5 predicted poor neurological outcome in nearly half of all patients, with a specificity of 90.8%.
- The accurate prediction of poor outcome in patients with OOHCA and STEMI, where the main cause of mortality remains hypoxic brain injury, would allow identification of risk distinct to clinical presentation.
- Since the risk score was derived and validated in retrospective cohorts, there is a need to prospectively validate this in larger cohorts across different systems of health care before routine clinical use.
Study Questions:
What is the predictive utility of a practical risk score for poor neurological outcome after out-of-hospital cardiac arrest (OOHCA) for use on arrival to a Heart Attack Center?
Methods:
The investigators included all patients over the age of 18 years who presented with OOHCA and had return of spontaneous circulation in the community between May 2012 and December 2017. Inclusion criteria for the registry were all patients with ST elevation on electrocardiogram and patients without ST elevation if there was absence of a noncardiac etiology, since this group represents patients recommended for the consideration of an early invasive approach by European Association of Percutaneous Cardiovascular Interventions and European Society of Cardiology guidelines. From May 2012 to December 2017, 1,055 patients had OOHCA, of whom 373 patients were included in the King's Out of Hospital Cardiac Arrest Registry. The authors performed prediction modeling with multivariable logistic regression to identify predictors of the primary outcome to derive a risk score. This was externally validated in two independent cohorts comprising 473 patients. The primary endpoint was poor neurological outcome, classified as Cerebral Performance Category 3–5 (severe disability–death) at follow-up of 6 months (blinded analysis).
Results:
Seven independent predictors of outcome were identified: missed (unwitnessed) arrest, initial nonshockable rhythm, nonreactivity of pupils, age (60-80 years: 1 point; >80 years: 3 points), changing intra-arrest rhythms, low pH <7.20, and epinephrine administration (2 points). The MIRACLE2 score had an area under the curve (AUC) of 0.90 in the development and 0.84/0.91 in the validation cohorts. Three risk groups were defined: low risk (MIRACLE2 ≤2: 5.6% risk of poor outcome); intermediate risk (MIRACLE2 3-4: 55.4% risk of poor outcome); and high risk (MIRACLE2 ≥5: 92.3% risk of poor outcome). The MIRACLE2 score had superior discrimination than the OOHCA (median AUC, 0.83 [0.818-0.840]; p < 0.001) and Cardiac Arrest Hospital Prognosis models (median AUC 0.87 [0.860-0.870]; p = 0.001) and equivalent performance with the Target Temperature Management score (median AUC 0.88 [0.876-0.887]; p = 0.092).
Conclusions:
The authors concluded that the MIRACLE2 is a practical risk score for early accurate prediction of poor neurological outcome after OOHCA, which has been developed for simplicity of use on admission.
Perspective:
This study derived and validated the MIRACLE2 risk score as a practical tool to predict poor neurological outcome at the time of index admission to a Heart Attack Center and report that a MIRACLE2 score of ≥5 predicted poor neurological outcome in nearly half of all patients, with a specificity of 90.8%. The accurate prediction of poor outcome in patients with OOHCA and ST-segment elevation myocardial infarction (STEMI), where the main cause of mortality remains hypoxic brain injury, would allow identification of risk distinct to clinical presentation. Furthermore, these findings might help define subgroups of patients where an early invasive approach might be futile. Finally, since the risk score was derived and validated in retrospective cohorts, there is a need to prospectively validate this in larger cohorts and across different systems of health care before its routine use.
Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Prevention, Stable Ischemic Heart Disease, Vascular Medicine, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Chronic Angina
Keywords: Acute Coronary Syndrome, Arrhythmias, Cardiac, Brain Injuries, Electrocardiography, Epinephrine, Heart Arrest, Myocardial Infarction, Neurologic Manifestations, Outcome Assessment, Health Care, Out-of-Hospital Cardiac Arrest, Risk Assessment, Secondary Prevention, ST Elevation Myocardial Infarction
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