INTERCENTER VARIABILITY IN OUTCOME FOR PATIENTS TREATED WITH DIRECT CORONARY ANGIOPLASTY DURING ACUTE MYOCARDIAL-INFARCTION

Background Direct coronary angioplasty is an effective therapy for acu te myocardial infarction, but its success may be dependent on both rea dy availability and operator skill. The purpose of this study was to i nvestigate the impact of the center performing direct coronary angiopl asty for acute myocardial infarction while controlling For parameters known to affect outcome. Methods and Results The study group consisted of 99 patients with ST elevation who were treated with direct angiopl asty in four high-volume centers. Patients were injected with techneti um-99m sestamibi intravenously and then taken to the cardiac catheteri zation laboratory. Antegrade flow was graded before and after direct c oronary angioplasty. Single photon emission computed tomography was pe rformed 1 to 6 hours after injection to measure myocardium at risk and residual blood flow to the jeopardized zone using previously publishe d quantitative methods. A repeat sestamibi injection and tomographic a cquisition were performed at hospital discharge to measure actual infa rct. size. There were no significant differences by center for baselin e clinical characteristics, mean myocardium at risk (29% to 37% left v entricle [LV]), time to reperfusion (3.1 to 4.1 hours), residual blood flow, infarct location, or antegrade flow. Despite these similarities , there were differences in outcome measures by center. Mean infarct s ize was as follows: center 1, 15%; center 2, 12%; center 3, 10%, cente r 4, 23% (all LV; p = 0.11). Mean left ventricular ejection fraction a t discharge also demonstrated significant differences: center 1, 0.57; center 2, 0.47; center 3, 0.53; center 4, 0.47 (p = 0.002). The preva lence of Thrombolysis in Myocardial Infarction grade 3 flow after angi oplasty significantly differed by center: center 1, 92%; center 2, 94% ; center 3, 87%; center 4, 71%; (p = 0.01). There was a low mortality rate for all four centers ranging from 0% to 6%. After adjustment for myocardium at risk, residual blood flow, and time to reperfusion, the primary outcome of the center where the angioplasty was performed was an independent determinant of both infarct size and left ventricular e jection fraction. Conclusion The success of direct coronary angioplast y in reducing infarct size and preserving left ventricular function de pends an the center performing the procedure. Direct measurement of th e effectiveness of this reperfusion modality in community practice is required to assess the impact of this effect.