Is the residual translesional pressure gradient useful to predict regional myocardial perfusion after percutaneous transluminal coronary angioplasty?

Routine assessment of the severity of a coronary artery lesion with coronary cineangiography is limited by its variability and poor correlation with blood flow and postmortem findings. In this investigation, we compared the usefulness of the final coronary artery transiesional pressure gradient and the final angiographic coronary percent stenosis to assess immediate percutaneous transluminal coronary angioplasty (PTCA) success. To accomplish this, pressure gradients and percent stenoses were compared to stress thallium-201 regional myocardial perfusion before and after 56 uncomplicated PTCAs in 51 patients with single-vessel coronary artery disease. There were 39 men and 12 women; their mean age was 59 ± 12 years. No patient had evidence of myocardial infarction. A new quantitative method to assess regional myocardial perfusion was used. Patients exercised for 433 ± 130 seconds before PTCA and for 545 ± 126 seconds after PTCA (p < 0.001). Group coronary stenosis and translesional pressure gradient decreased from 77 ± 11% and 48 ± 5 mm Hg, respectively, before PTCA, to 25 ± 11% and 9 ± 5 mm Hg, respectively, after PTCA (p < 0.001). Regional myocardial perfusion in the segment of the diseased (dilated) coronary artery increased after PTCA from 77 ± 17% to 94 ± 9% (p < 0.001). Although a significant relationship was noted between regional myocardial perfusion and percent stenosis and translesional pressure gradient, a large individual scatter was present (r values lower than 0.55). We conclude that the final translesional pressure gradient during PTCA is not a better measure of immediate PTCA success than the angiographic percent stenosis.