The impact of revascularization on myocardial blood flow as assessed by positron emission tomography

Revascularization aims to improve myocardial perfusion. However, changes in regional artery-specific quantitative perfusion after revascularization have not been systematically investigated. It is unclear whether artery-specific thresholds for coronary flow capacity (CFC) and/or relative perfusion predict improved stress perfusion after revascularization. We sought to determine the impact of revascularization based on predefined, artery-specific, severity size thresholds for CFC and/or relative perfusion defects.

Fifty patients underwent PET imaging before revascularization and then prospectively within 90 days after revascularization. Changes in regional myocardial blood flow (MBF) were stratified based on baseline perfusion abnormalities, baseline reduced CFC, and whether revascularization was performed in that region.

Following angiographic stenosis-directed revascularization, in regions with relative perfusion abnormalities and decreased CFC, stress MBF (sMBF) increased by 0.51 cm³/min/g (59%) from baseline (p < 0.001). In regions without baseline perfusion abnormalities and yet decreased CFC, sMBF increased by 0.35 cm³/min/g (40%) from baseline (p < 0.001). In regions without perfusion abnormalities and normal CFC, sMBF did not increase significantly (+0.07 cm³/min/g, p = 0.56). Patients in whom revascularization was concordant with abnormal PET findings showed increased whole-heart sMBF (+0.22 cm³/min/g, p < 0.001), but in patients in whom revascularization was targeted only to regions without perfusion abnormalities or low CFC, sMBF did not change significantly (-0.06 cm³/min/g, p = 0.38).

Revascularization targeted to regions with reduced CFC and relative perfusion abnormalities on baseline PET yielded significant improvements in sMBF. When revascularization was performed in regions without reduced CFC, sMBF did not improve.