Primary angioplasty versus intravenous thrombolysis in acute myocardial infarction: Can we define subgroups of patients benefiting most from primary angioplasty? Results from the pooled data of the Maximal Individual Therapyin Acute Myocardial Infarction Registry and the Myocardial Infarction Registry

OBJECTIVES We sought to determine the effectiveness of primary angioplasty compared with thrombolysis in clinical practice. BACKGROUND In clinical practice, primary angioplasty for the treatment of a cute myocardial infarction (AMI) has not yet been proven more effective tha n intravenous thrombolysis, nor have subgroups of patients been identified who would perhaps benefit from primary angioplasty. METHODS The pooled data of two AMI registries-the Maximal Individual TheRap y in Acute myocardial infarction (MITRA) study and the myocardial Infarctio n Registry (MIR)-were analyzed. A total of 9,906 lyric-eligible patients wi th AMI, with a pre-hospital delay of less than or equal to 12 h, were treat ed with either primary angioplasty (n = 1,327) or thrombolysis (n = 8,579). RESULTS Despite differences in the patients' characteristics and concomitan t diseases between the two groups, the prevalence of adverse risk factors w as balanced. Univariate analysis of hospital mortality showed a more favora ble course for patients treated with primary angioplasty: 6.4% versus 11.3% (odds ratio [OR] 0.54, 95% confidence interval [CI] 0.43 to 0.67). This wa s confirmed by logistic regression analysis (multivariate OR 0.58, 95% CI 0 .44 to 0.77). Primary angioplasty was associated with a lower mortality in all subgroups analyzed. We observed a significant correlation between morta lity and absolute risk reduction (r = 0.82, p < 0.0001) in the different su bgroups: as mortality increased, there was an increase in absolute benefit of primary angioplasty compared with thrombolysis. CONCLUSIONS These large registry data showed the effect of primary angiopla sty to be more favorable than thrombolysis for the treatment of patients wi th AMI in clinical practice. This effect was not restricted to special subg roups of patients. As mortality increased, the absolute benefit of primary angioplasty also increased. (J Am Coll Cardiol 2001;37:1827-35) (C) 2001 by the American College of Cardiology.