Effects of hospital volume on long-term outcomes after percutaneous transluminal coronary angioplasty after acute myocardial infarction

Background Volume of procedures has been associated with short-term outcome after percutaneous transluminal coronary angioplasty. However, the effect of hospital procedural volume on long-term outcome after PTCA is unknown. Methods and Results We analyzed the physician claims and discharge data of 6635 patients who underwent PTCA after acute myocardial infarction (AMI) between 1991 and 1995 in the province of Quebec, Canada. For each administrative year, hospitals in which PTCA was performed were classified into 3 groups: low-volume, <200 procedures per year; medium-volume, 200 to 399 procedures per year; and high-volume, greater than or equal to400 procedures per year. Compared with patients in medium-volume and high-volume hospitals, patients in low-volume hospitals were older, had more recent AMI, and were less likely to have been transferred for PTCA. After adjustment for baseline differences, patients in the low-volume and medium-volume groups were more likely to undergo CABG within 6 months compared with patients in the high-volume group (odds ratio [OR] 2.1, 95% Cl 1.3-3.3, and OR 1.5, 95% CI 1.2-1.9, respectively). In contrast, patients in the low-volume and medium-volume groups were less likely than patients in the high-volume group to undergo repeat PTCA within 6 months (OR 0.37, 95% Cl 0.24-0.58, and OR 0.8, 95% Cl 0.70-0.92, respectively). At 6 months, adjusted rates of repeat revascularization, recurrent AMI, or death did not differ between the 3 groups. Conclusion Overall adverse event rates at 6 months after PTCA do not differ between hospital volume groups. The higher rate of CABG in low-volume hospitals and the higher rate of repeat PTCA in high-volume hospitals may represent different physician preferences for the treatment of failed PTCA rather than higher complication rates.