The effect of coronary revascularization on regional myocardial blood flow as assessed by stress positron emission tomography.

OBJECTIVES: We examined whether regional improvement in stress myocardial blood flow (sMBF) following angiography-guided coronary revascularization depends on the existence of a perfusion defect on positron emission tomography (PET).

BACKGROUND: Percent stenosis on coronary angiography often is the main factor when deciding whether to perform revascularization, but it does not reliably relate to maximum sMBF. PET is a validated method of assessing sMBF.

METHODS: 19 patients (79% M, 65 ± 12 years) underwent PET stress before and after revascularization (17 PCI, 2 CABG). Pre- and post-revascularization sMBF for each left ventricular quadrant (anterior, septal, lateral, and inferior) was stratified by the presence or absence of a baseline perfusion defect on PET and whether that region was revascularized.

RESULTS: Intervention was performed on 40 of 76 quadrants. When a baseline perfusion defect existed in a region that was revascularized (n = 26), post-revascularization flow increased by 0.6 ± 0.7 cc/min/g (1.2 ± 0.4 vs 1.7 ± 0.8, P < 0.001). When no defect existed but revascularization was performed (n = 14), sMBF did not change significantly (1.7 ± 0.3 vs 1.5 ± 0.4 cc/min/g, P = 0.16). In regions without a defect that were not revascularized (n = 29), sMBF did not significantly change (2.0 ± 0.6 vs 1.9 ± 0.7, P = 0.7).

CONCLUSIONS: When a stress-induced perfusion defect exists on PET, revascularization improves sMBF in that region. When there is no such defect, sMBF shows no net change, whether or not intervention is performed in that area. PET stress may be useful for identifying areas of myocardium that could benefit from revascularization, and also areas in which intervention is unlikely to yield improvement in myocardial blood flow.