We observed a threefold variation in the ratio of PCI:CABG procedures across the four hospital groups, from a mean of 1.6 in the group of hospitals with the lowest ratios (< 2.0) to a mean of 4.6 in the group with the highest ratios (> 3.2), as well as a fivefold variation across the individual hospitals, from 1.3 to 6.1. The variation was not primarily the result of differences in patient characteristics or the utilization of primary PCI (i.e., for emergent ST-segment elevation myocardial infarction). Rather, it appeared to reflect variations in treatment preferences and practice styles of the cardiologists performing the index catheterizations with regard to the management of patients with non-emergent multivessel disease, patients who could potentially be recommended for either PCI or CABG surgery.17
Although coronary anatomy was the most important individual-level predictor of whether a patient received PCI or CABG surgery, there was significant residual variation that could be attributed to hospital and physician factors. These variations in revascularization practice may be clinically significant because the choice of PCI or CABG surgery may result in different long-term outcomes for patients.9–13
Our results are consistent with those from previous studies confirming the primary role of the cardiologist who performs the index catheterization in determining the mode of revascularization ultimately provided. Thompson and colleagues, using data from coronary angiography registries in the provinces of British Columbia and Alberta, found a similar association between the treatment recommended by the cardiologist immediately after angiography and the treatment received by the patient.18
In New York State, Hannan and colleagues observed that many patients who had indications for CABG surgery (according to the American College of Cardiology/American Heart Association guidelines) at the time of angiography received multivessel PCI and never saw a cardiac surgeon.19
Although previous studies have shown that interventional cardiologists are more likely to recommend PCI and cardiac surgeons are more likely to recommend CABG surgery for patients with similar indications,20,21
we found substantial variation among cardiology specialists across different hospitals in terms of their revascularization practices.
The trend toward increasing PCI:CABG ratios and increasing use of ad hoc PCI (immediately after cardiac catheterization) have led some observers to raise concerns about potential conflicts of interest, whereby an interventional cardiologist may be in a position both to make a diagnosis and to offer immediate treatment to a patient without involving other members of the health care team such as the referring physician and a cardiac surgeon.22,23
Surveys of patients who underwent PCI and CABG surgery showed that more than half of them had not been offered alternative treatment options.23
Although emergent treatment with primary PCI is beneficial for patients with ST-segment elevation MI, concerns have been raised about whether the widespread practice of immediate PCI after catheterization in patients with more stable multivessel disease adequately provides for informed consent.22,23
Recent guidelines from the Task Force on Myocardial Revascularization of the European Society of Cardiology and the European Association for Cardio-Thoracic Surgery recommend that ad hoc PCI be avoided in most patients with multivessel disease who are clinically stable.6
In our study, patient cases were infrequently discussed at formal, multidisciplinary case conferences. We believe there are opportunities to improve transparency and consistency of decision-making around the mode of revascularization and suggest that an efficient multidisciplinary team approach to decision-making be established for patients who could potentially undergo either PCI or CABG surgery. Such a team could include an interventional cardiologist, the physician who performed the catheterization if not an interventional cardiologist, a cardiac surgeon, the referring physician when feasible, and the patient. Public release of information on the long-term outcomes of PCI and CABG surgery by centre, and increased use of patient decision aids may also help patients make fully informed choices about their treatment options.24
Our study has several limitations. First, it was not designed to identify an ideal PCI:CABG ratio. Further study of the outcomes of patients who received treatment at hospitals with different procedure ratios would help identify whether certain practice patterns are associated with better long-term outcomes for patients.
Second, variations in the PCI:CABG ratio could reflect provider knowledge of local outcomes for both procedures. We could not assess whether this was an important consideration from the available data.
Third, we did not have information on the extent to which patients with multivessel disease made a fully informed decision about the choice of PCI versus CABG surgery. However, the high frequency of ad hoc PCI suggests that many of these decisions were likely made without the involvement of a cardiac surgeon.
Fourth, we could not determine from the available data whether there was underuse of PCI among some patients at hospitals with lower PCI:CABG ratios who might have benefitted from PCI.
Finally, variations in the use of medical therapies may have influenced the results of our study. However, a full exploration of this topic was beyond the scope of our study, because we focused only on the utilization of PCI and CABG surgery.
We found that the recommendation of the physician performing the diagnostic catheterization and the treating hospital were strong independent predictors of the mode of revascularization. Our findings may have important clinical and policy implications and are likely to stimulate debate and discussion about the optimal approach to decisions about the mode of revascularization for patients with advanced coronary artery disease. Although many patients may still prefer PCI because it is less invasive, cardiac surgeons need to be more involved in clinical decision-making when patients are candidates for either PCI or CABG surgery. Patients need to be fully informed about the benefits and risks of all alternative treatment options. Opportunities exist to improve transparency and consistency around the decision-making process for coronary revascularization, most notably among patients with non-emergent multivessel disease.