Coronary angiography following acute myocardial infarction in Ontario, Canada.

Background — The role of scientific evidence in shaping recommendations on capacity targets and cardiovascular technology utilization is unclear.

Methods — The temporal growth in the use of coronary angiography services and the use of statins after an acute myocardial infarction (AMI) was determined for all patients older than 65 years admitted to any hospital in Ontario, Canada, between 1992 and 2004. A Bayesian change-point regression model was used to determine the rate of maximum uptake (inflection point) for use of cardiac catheterization service and statins after AMI. The inflection points were compared with the corresponding publication dates of the first positive evidence for outcome efficacy of use of cardiac catheterization service and statins after AMI as obtained from randomized control trials.

Results — The use of post-AMI coronary angiography closely mirrored overall temporal increases in cardiac catheterization capacity between 1992 and 2004 (r = 0.95, P<.001). The inflection point for post-AMI angiography service use was September 1998, 11 months before the publication of the first positive randomized controlled trial demonstrating benefit of routine post-AMI angiography. Conversely, the inflection point for statin therapy occurred in October 1998, 47 months after the publication of the first positive randomized controlled trial demonstrating the benefits of statin therapy for the secondary prevention of coronary artery disease. These findings were consistent regardless of the presence of on-site cardiac catheterization facilities at the admitting AMI institution and patient illness severity levels.

Conclusion — The proliferation of cardiac catheterization in Ontario is attributable to factors other than the emergence of published scientific evidence.