Relationship Between Risk Stratification at Admission and Treatment Effects of Early Invasive Management Following Fibrinolysis: Insights From the Trial of Routine Angioplasty and Stenting After Fibrinolysis to Enhance Reperfusion in Acute Myocardial Infarction (TRANSFER-AMI)

Study Questions:

Does risk stratification using the Global Registry of Acute Coronary Events (GRACE) influence effectiveness of early routine percutaneous coronary intervention (PCI) after fibrinolysis for ST-segment elevation myocardial infarction (STEMI)?

Methods:

This was a post-hoc subgroup analysis of Trial of Routine Angioplasty and Stenting after Fibrinolysis to Enhance Reperfusion in Acute Myocardial Infarction (TRANSFER-AMI) patients who were stratified by the GRACE risk score. In TRANSFER-AMI, 1,059 patients with acute STEMI who received tenecteplase in 53 Canadian hospitals were randomized to standard medical treatment (rescue PCI if required or delayed coronary angiography) versus immediate transfer for PCI within 6 hours of fibrinolysis. Eligibility requirements included admission for anterior or inferior STEMI with other high-risk features including tachycardia, hypotension, Killip class II-III, or electrocardiogram evidence of posterior or right ventricular involvement. Major exclusion criteria included cardiogenic shock (before enrollment), previous PCI within the past month, previous coronary artery bypass grafting, or availability of timely PCI. For each patient, a GRACE risk score was calculated based on age, heart rate, systolic blood pressure, Killip class, cardiac arrest, ST-segment deviation, abnormal biomarkers, and serum creatinine. Since data regarding cardiac arrest on admission were not collected, and this is a variable included in the GRACE risk score, the investigators used in-hospital arrest instead. The primary outcome of interest was death or re-MI at 30 days.

Results:

The mean GRACE risk score for the cohort was 124. Patients were classified as low-intermediate (n = 889) or high risk, defined as a GRACE risk score ≥155 (n = 170). Patients with a high risk score were older, more likely to be female, diabetic, and have a prior history of MI or heart failure. There was a significant interaction between treatment assignment and risk status for the composite endpoint of death/re-MI at 30 days (p for interaction < 0.001). Compared with the standard treatment, pharmacoinvasive therapy (early routine PCI) was associated with a lower rate of death/re-MI at 30 days in the low-intermediate risk stratum (8.1 vs. 2.9%, p < 0.001), but a higher rate of death/re-MI in the high-risk group (13.8 vs. 27.8%, p = 0.025). They found similar heterogeneity in the treatment effects on 30-day mortality and death/re-MI at 1 year (p for interaction = 0.008 and 0.001, respectively), when the GRACE risk score was analyzed as a continuous variable (p for interaction < 0.001) and when patients were stratified by the Thrombolysis In Myocardial Infarction (TIMI) risk score (p for interaction = 0.001).

Conclusions:

The authors concluded that the treatment effects of a pharmacoinvasive strategy after fibrinolysis for STEMI differ by clinical characteristics. Patients with a low-intermediate GRACE risk had improved outcomes with early PCI after fibrinolysis, whereas high-risk patients had worse outcomes.

Perspective:

This study highlights the clinical usefulness of risk scores in management of STEMI patients. The GRACE risk score allowed for identification of patients who benefited by early, aggressive invasive management.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Myocardial Infarction, Biological Markers, Coronary Angiography, Fibrinolysis, Canada, Electrocardiography, Angioplasty, Heart Rate, Percutaneous Coronary Intervention, Pyridazines


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