Left ventricular function at 3 months after successful thrombolysis: Impact of reocclusion without reinfarction on ejection fraction, regional function, and remodeling

Abstract

Background: After successful thrombolysis for acute myocardial infarction, reocclusion is observed in about 30% of patients after 3 months and usually occurs without reinfarction. We studied the impact of reocclusion without reinfarction on global and regional left ventricular function and on remodeling during that period. Methods and Results: The patients for this analysis constituted a subset of those enrolled in the APRICOT-trial, which was designed to study the efficacy of antithrombotics on the prevention of reocclusion. Patients were selected who had a left anterior descending- or right coronary artery-related myocardial infarction, had an angiographically patent infarct-related vessel when studied <48 hours after intravenous thrombolysis, and underwent repeat cardiac catheterization at 3 months. Paired contrast ventriculograms of quality sufficient to analyze regional wall motion, global ejection fraction, and ventricular volumes were analyzed in 129 patients. Enzymatic infarct size and baseline left ventricular function as well as other baseline characteristics were similar in patients with (n=34) and without (n=95) reocclusion. Ejection fraction improved in anterior infarction without reocclusion from 47±10% to 54±13% (P=.0001) but not with reocclusion (baseline, 48±13%; 3 months, 48±16%). No improvement was seen in inferior infarction with or without reocclusion. Persistent patency allowed preservation of end-systolic volume index (ESVI) at 3 months (37±14 mL/m2) to baseline level (38±13 mL/m2), with a better chance for improvement of >10 mL/m2 without reocclusion in those with baseline values >40 mL/m2. After reocclusion, in contrast, ESVI increased from 37±14 to 43±20 mL/m2 (P=.08). Comparable mean changes of ESVI in response to persistent patency or reocclusion were seen in anterior versus inferior infarction. Recovery of infarct zone contractility was impaired by reocclusion, both in terms of abnormality of segment shortening and expressed in the number of segments showing abnormal wall motion. In anterior but not in inferior infarction, infarct zone contractility was better with good collaterals to the reoccluded artery compared with poor collaterals. Conclusions: After successful thrombolysis for acute myocardial infarction, reocclusion without reinfarction withholds salvaged myocardium from regaining contractility. This has deleterious consequences for regional and global left ventricular function and for remodeling. To further optimize prognosis in patients after thrombolysis, future research should focus on the prevention of reocclusion and should evaluate revascularization therapy in patients with reocclusion.