Improvement in transient and ‘Persistent’ perfusion defects on early and late post-exercise thallium-201 tomograms after coronary artery bypass grafting.

In order to assess the changes in the number and severity of transient and persistent myocardial perfusion defects before and after coronary artery bypass grafting (CABG), early and late post-exercise thallium-201 (tl-201) tomography was performed in 25 patients, on average 10 days before and 2.5 months after CABG. Six patients had a previous Q wave myocardial infarction. Comparing the pre- and post-CABG exercise test data (symptom limited bicycle ergometry) showed an improvement in working capacity (from 129±34 to 145 ±35 W, P<0.05) and a reduction in exercise induced angina from 77 to 9% of the patients(P<0.001). From the tomographic data, six short axis and three sagittal cross-sections of the left ventricular myocardium were reconstructed. In each patient study, a total of 51 myocardial segments were defined and analysed in a semi-quantitative manner by means of a five point scoring method indicative of the severity of a defect (from 0 = normal tl-201 uptake to 4 = absence of tl-201 activity). In this patient population the total number of segements with transient tl-201 perfusion defects decreased from 11.0±7 segments per patient (mean±SD; before surgery to 4.9±4 after surgery (p<0.01); the number of segments with ‘persistent’ tl-201 defects decreased as well from 7.5±6 to 3.9±4 segments per patient (P<0.03). On average, the severity score of transient perfusion defects decreased from 17.7±12 to 7.1±6 per patient (mean±SD.P<0.01) and that of ‘ persistent ’ defects from 17.4±15 to 8.4 ± 9 (p<0.03). From these data it may be concluded, that the apparent reversibility of certain tl-201 defects are compatible not only with scar tissue, but also with a reversibly ischaemic myocardium. [ABSTRACT FROM PUBLISHER]