Limitation of infarct size by fixed coronary arterial stenosis maintained during reperfusion

Background The effect on infarct size of a pre-infarction high-grade, fixed coronary arterial stenosis maintained during reperfusion, was evaluated. Methods. This experimental study was carried out in the research laboratory of a University Hospital. A canine occlusion-reperfusion model was used. T wenty-eight dogs underwent proximal left anterior descending (LAD) coronary artery occlusion (O). In Group 1 (n=6) the O lasted for 6 hours. In Group 2 (n=6) the O lasted for 2 hours followed by 4 hours of reperfusion (R), In Group 3 (n=3), LAD was stenosed for 30 minutes followed by O for 6 hours. In Group 4 (n=7) LAD was stenosed for 30 minutes followed by O for 2 hours and then 4 hours of R during which the artery was kept stenosed at the same degree (fixed) as the initial one. In Group 5 (n=6) the protocol was ident ical to Group 4 with the additional use of the intra-aortic balloon pump du ring R, Results, The infarcted myocardium was almost the same in Groups 1 and 3 (80 .0 +/- 10.6% vs 77.3 +/-3.8%, respectively, p=NS), but less in Group 2 (59. 0 +/- 19.9%, p=0.046 vs Group 1). There were no hemodynamic differences bet ween Groups 4 and 5 and the infarcted myocardium was almost identical in bo th groups (37.7 +/- 18.8% and 38.7 +/- 19.1%, respectively, p=NS). The comb ined results of Groups 4 and 5, regarding the infarcted myocardium, was 38. 1 +/- 18% (p=0.037 vs Group 2), Conclusions. In this acute coronary occlusion model, a pre-existing high-gr ade stenosis that maintained during reperfusion increased the amount of sal vaged ischemic myocardium.