Relation between hospital specialization with primary percutaneous coronary intervention and clinical outcomes in ST-segment elevation myocardial infarction - National Registry of Myocardial Infarction-4 Analysis

Background - Hospitals with primary percutaneous coronary intervention (PPCI) capability may choose to predominately offer PPCI to their patients with ST-segment elevation myocardial infarction (STEMI), or they may selectively offer PPCI or fibrinolytic therapy based on patient and hospital-level factors. Whether a greater level of hospital specialization with PPCI is associated with better quality of care is unknown. Methods and Results - We analyzed data from the National Registry of Myocardial Infarction-4 to compare in-hospital mortality and times to treatment in STEMI across different levels of hospital specialization with PPCI. We divided 463 hospitals into quartiles of PPCI specialization based on the relative proportion of reperfusion-treated patients who underwent PPCI ( <= 34.0%, > 34.0 to 62.5%, > 62.5 to 88.5%, > 88.5%). Hierarchical multivariable regression assessed whether PPCI specialization was associated with better outcomes, after adjusting for patient and hospital characteristics, including PPCI volume. We found that greater PPCI specialization was associated with a lower relative risk of in-hospital mortality in patients treated with PPCI ( adjusted relative risk comparing the highest and lowest quartiles, 0.64; P = 0.006) but not in those treated with fibrinolytic therapy. Compared with patients at hospitals in the lowest quartile of PPCI specialization, adjusted door-to-balloon times in the highest quartile were significantly shorter (99.6 versus 118.3 minutes; P < 0.001), and the likelihood of door-to-balloon times exceeding 90 minutes was significantly lower ( relative risk, 0.78; P < 0.001). Adjusting for PPCI specialization diminished the association between PPCI volume and clinical outcomes. Conclusions - Greater specialization with PPCI is associated with lower in-hospital mortality and shorter door-to-balloon times in STEMI patients treated with PPCI.