AdenosINe Sestamibi Post-InfaRction Evaluation (INSPIRE) Trial - INSPIRE

Description:

The goals of the INSPIRE trial were to evaluate: 1) the degree to which the detection of scintigraphic ischemia tracks prognosis, and 2) whether maximal medical therapy is as effective as coronary revascularization for reducing ischemia and improving outcome in a randomized subset of high-risk patients with myocardial infarction (MI).

Study Design

Patients Enrolled: 728
Mean Follow Up: One year
Mean Patient Age: Mean age 63 years
Female: 31

Patient Populations:

Acute MI within the prior 10 days, clinically stable, and age ≥18 years

Exclusions:

Clinical instability, acute primary PCI, left bundle branch block, or contraindication to adenosine

Primary Endpoints:

Cardiac death, reinfarction, acute coronary syndrome, or heart failure

Drug/Procedures Used:

Baseline adenosine technetium-99m sestamibi single-photon emission computed tomography (SPECT) was performed within 10 days of acute MI and patients were classified as low (n=242), intermediate (n=213), or high (n=273) risk based on the SPECT total and ischemic left ventricular (LV) perfusion defect size. Low-risk patients had a small (<20%) LV perfusion defect size and did not undergo coronary angiography except for clinical instability. High-risk patients had a large (>20%) and predominantly ischemic (>10%) LV perfusion defect size. All other patients fell into the intermediate-risk category.

Among the high-risk patients, those with a LV ejection fraction (LVEF) <35% by gated SPECT (n=68) had coronary angiography with the intent to revascularize, and those with a LVEF ≥35% were randomized to receive either intensive medical therapy or coronary revascularization (n=205). A second SPECT was performed after each assigned anti-ischemic therapy was optimized.

Principal Findings:

Approximately 70% of patients underwent the baseline SPECT by day 4. Follow-up SPECT was performed a median of 66 days after the baseline SPECT. Lytic therapy was used in 35% of patients. Death or MI occurred in <3% of patients in the low-risk group compared with >10% of patients in the high-risk group.

Among the high-risk patients randomized to either coronary revascularization or intensive medical therapy, revascularization was performed in 74% of the invasive group and 22% of the medical group (p<0.001). Both strategies were associated with similar decreases in total perfusion defect size (-17.8% in the invasive group and -16.2% in the medical group, p=0.36) and ischemic perfusion defect size (-16.2% in the invasive group and -15.0% in the medical group, p=0.44). Changes in LVEF were also similar in both groups (4.6% in the invasive group and 4.7% in the medical group, p=0.93).

Interpretation:

Among clinically stable post-MI patients, risk stratification based on SPECT perfusion defect size was associated with adverse clinical events.

Additionally, SPECT-assessed high-risk patients treated with an invasive or medical strategy showed similar improvements in scintigraphic ischemia. While provocative, the sample size in the randomized comparison group was small and a surrogate endpoint was assessed, rather than clinical events. As such, the results should be interpreted with caution and should be viewed as hypothesis-generating.

References:

Mahmarian JJ, et al. A Multinational Study to Establish the Value of Early Adenosine Technetium-99m Sestamibi Myocardial Perfusion Imaging in Identifying a Low-Risk Group for Early Hospital Discharge After Acute Myocardial Infarction. J Am Coll Cardiol 2006;48:2448-57 and J Am Coll Cardiol 2006;48:2458-67.

Presented by Dr. John J. Mahmarian at the American College of Cardiology Annual Scientific Session, March 2004.

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

Keywords: Myocardial Infarction, Follow-Up Studies, Biological Markers, Coronary Angiography, Tomography, Emission-Computed, Single-Photon, Technetium Tc 99m Sestamibi


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