Functional stress imaging to predict abnormal coronary fractional flow reserve: the PACIFIC 2 study

Area of Science:

• Cardiology
• Medical Imaging
• Diagnostic Performance

Background:

• Non-invasive imaging diagnostic performance in patients with prior coronary artery disease (CAD) lacks prospective head-to-head comparative studies.
• Patients with prior myocardial infarction (MI) or percutaneous coronary intervention (PCI) represent a high-risk population for recurrent ischemic events.

Purpose of the Study:

• To compare the diagnostic performance of qualitative single-photon emission computed tomography (SPECT), quantitative positron emission tomography (PET), and qualitative magnetic resonance imaging (MRI).
• To evaluate these modalities in patients with prior MI or PCI presenting with new symptoms of ischemic CAD.

Main Methods:

• Prospective clinical study involving 189 patients with prior MI and/or PCI and new ischemic symptoms.
• All patients underwent 99mTc-tetrofosmin SPECT, [15O]H2O PET, and MRI.
• Invasive coronary angiography with fractional flow reserve (FFR) ≤0.80 as the reference standard for significant CAD.

Main Results:

• PET demonstrated higher sensitivity (81%) compared to SPECT (67%) and MRI (66%).
• No significant difference in specificity was observed among SPECT, PET, and MRI.
• Diagnostic accuracy was highest for PET (75%), though not statistically different from SPECT (65%) and MRI (64%) when using FFR ≤0.80.

Conclusions:

• SPECT, PET, and MRI showed no significant difference in accuracy for diagnosing FFR-defined significant CAD in patients with prior MI/PCI.
• The overall diagnostic performance of these non-invasive imaging modalities in this high-risk population was found to be discouraging.
• The additive value of non-invasive imaging in patients with prior MI/PCI requires further investigation.