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Very early risk stratification after thrombolytic therapy with a bedside myoglobin assay and the 12-lead
J A De Lemos1, E M Antman, R P Giugliano
1Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA. jdelemos@rics.bwh.harvard.edu
Insights
A negative baseline myoglobin assay and complete ST resolution significantly reduce mortality risk in ST-segment elevation myocardial infarction patients. These rapid tests aid early risk stratification and patient triage after thrombolytic therapy.
Area of Science:
- Cardiology
- Biomarkers
- Diagnostic Tools
Background:
- Current prognosis criteria for ST-elevation myocardial infarction (STEMI) lack consideration of reperfusion therapy and baseline cardiac markers.
- There is a need for improved risk stratification tools in STEMI management.
Purpose of the Study:
- To evaluate the combined utility of a baseline myoglobin assay and early ST-segment resolution for risk stratification in STEMI patients.
- To assess the predictive value of these markers for 30-day mortality.
Main Methods:
- A prospective substudy of the InTIME-II trial included 2079 STEMI patients.
- Baseline myoglobin levels were assessed immediately before thrombolysis.
- Serial electrocardiograms were used to categorize ST-segment resolution at 60-90 minutes post-thrombolysis.
Main Results:
- A negative baseline myoglobin assay was associated with a 3.3% mortality rate versus 8.9% for a positive assay (P <.0001).
- Complete ST resolution correlated with the lowest mortality (2.4%), while no ST resolution had the highest (8.1%) (P <.0001 for trend).
- Both positive myoglobin and ST resolution <70% were independent predictors of increased 30-day mortality.
Conclusions:
- A bedside risk assessment using myoglobin assay and ST resolution is feasible within 90 minutes post-thrombolysis.
- This strategy offers a simple, rapid, and inexpensive method for patient triage after thrombolytic therapy.
- Early identification of high-risk patients can guide subsequent management decisions.
Background:
Available clinical criteria to estimate prognosis in patients with evolving ST-segment elevation myocardial infarction do not consider the impact of reperfusion therapy and do not incorporate measurement of baseline levels of cardiac serum markers. We evaluated the combination of a baseline myoglobin assay and early (60- to 90-minute) ST resolution for risk stratification after ST-segment elevation myocardial infarction.
Methods:
In a prospective substudy of the Intravenous nPA for Treatment of Infarcting Myocardium Early-II (InTIME-II) trial carried out in 2079 patients, a rapid qualitative assay for myoglobin was performed immediately before thrombolysis. Serial 12-lead electrocardiograms were performed at baseline and 60 to 90 minutes after thrombolysis. ST resolution was categorized as complete (>/=70%), partial (30% to <70%), or none (<30%).
Results:
Mortality rate at 30 days was 3.3% in the 905 patients with a negative baseline myoglobin assay versus 8.9% in the 527 patients with a positive assay (P <.0001). Mortality rate was lowest (2.4%) among the 614 patients with complete ST resolution, intermediate (4.9%) among the 512 patients with partial ST resolution, and highest (8.1%) among the 540 patients with no ST resolution (P <.0001 for trend). In a logistic regression model incorporating other baseline predictors of 30-day mortality rate, both a positive myoglobin assay (relative risk 1.98, 95% confidence interval 1.00-3.90) and ST resolution <70% (relative risk 2.86, 95% confidence interval 1.22-6.69) were independently associated with increased mortality rate. At 30 days, mortality rate was 0.4% among patients with a negative myoglobin assay and complete ST resolution, 4.8% among patients with either a positive myoglobin assay or ST resolution <70%, and 9.6% among those with both a positive myoglobin ratio and ST resolution <70% (P <.001 for trend).
Conclusions:
Within 90 minutes after administering thrombolytic therapy for acute myocardial infarction, clinicians can determine the risk for death at the patient's bedside with a hand-held myoglobin assay and 2 serial 12-lead electrocardiograms. A strategy using these 2 simple, rapid, and inexpensive tests may facilitate triage after thrombolytic therapy.