Assessment of myocardial perfusion by positron emission tomography in patients with end-stage coronary artery disease treated with percutaneous myocardial revascularization

Background Reportedly, patients with persistent refractory angina due to end-stage coronary artery disease (CAD) notamenable to traditional revascularization techniques have experienced symptomatic relief following laserrevascularization, either surgical transmyocardial revascularization (TMR) or percutaneous myocardial revascularization(PMR). In spite of several hypotheses (i.e., channel patency, placebo effect, denervation, neoangiogenesis), themechanism of action and the benefit remains controversial.Methods A prospective trial utilizing positron emission tomography (PET) was conducted as an attempt to correlatequantified myocardial blood flow (MBF) to clinical improvement following PMR. Thirteen consecutive patients with anginaclass >Ⅱ in spite of maximal medical treatment underwent PMR with a holmium:yttrium-aluminum-garnet (Ho:YAG) laser.MBF at rest and under hyperemia was assessed by [13N]ammonia PET at baseline, 3 and 6 months following PMR.Results Mean angina class and exercise tolerance time improved at 6 months compared with baseline (P <0.001). Theclinical results were accompanied with an improvement in hyperemic MBF (P=0.05) and a reduction in minimal coronaryresistance (MCR; P <0.05) in PMR-treated segments. Opposite effects, reduced hyperemic MBF and increased MCR,were observed in nontreated segments. The increase in MCR in nontreated segments revealed the favorable therapeuticimpact achieved in PMR-treated segments.Conclusion The results of this trial utilizing a quantitative technique to quantify myocardial perfusion link clinicalimprovement post-PMR to neoangiogenesis and consistently improved microcirculation.