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When choosing between percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery, the choice of revascularization strategy varies widely and is strongly influenced by the doctor who performs the diagnostic catheterization as well as the ‘culture’ of the hospital in which the procedure is performed. The Canadian study, published online December 12, 2011, ahead of print in the Canadian Medical Association Journal, did find, though, that single-vessel disease is most often treated with PCI, while left main disease is largely left to surgery.

For the Variation in Revascularization Practices in Ontario study, a research team led by Jack V. Tu, MD, of the University of Toronto (Toronto, Canada), examined chart review data from 8,972 patients who underwent an index cardiac catheterization from April 2006 to March 2007 at 1 of the 17 Ontario hospitals that provide invasive cardiac procedures. The cohort represented about 20% of all patients who had angiograms in the province during 2006.

The participating hospitals were classified into 4 categories according to the ratio of PCI to CABG, yielding similar numbers in each category:

• Low (< 2.0)
• Low-medium (2.0-2.7)
• Medium-high (2.8-3.2)
• High (> 3.2)

The mean overall PCI:CABG ratio was 2.7. There was a threefold variation in this ratio across the 4 hospital categories, with a fivefold variation across individual hospitals.

Most Variation in the Middle Range of Anatomic Complexity

In a multilevel logistic regression model, coronary anatomy was the strongest predictor of when PCI was chosen over CABG. Patients with single-vessel disease typically received PCI (88.4%-99.0% across the hospital ratio categories), whereas most patients with left main disease underwent CABG (80.8%-94.2% across the categories). Most of the variation centered on patients with multivessel disease. In fact, there was a strong correlation (R = 86%) between a hospital’s PCI:CABG ratio among patients with multivessel disease and its overall PCI:CABG ratio.

The next strongest predictors of revascularization approach were the clinical indications for the procedure and the PCI:CABG ratio category of the hospital where it was performed (table 1).

Table 1. Predictors of Likelihood of PCI vs. CABG After Angiography

 
Drilling down into factors that contributed to variation across hospitals, the investigators found a correlation between the treatment recommended by the cardiologist who performed the index catheterization and the type of revascularization the patient ultimately received. Patients catheterized by an interventional cardiologist at a center with a high PCI:CABG ratio were more likely to choose PCI over surgery. The ‘culture’ of the hospital also played a role insofar as noninterventional cardiologists at centers with a high PCI:CABG ratio were more likely than those at centers with a lower ratio to recommend PCI over surgery (P < 0.001).

The proportion of PCI procedures performed ad hoc (ie, in the same setting as diagnostic catheterization) was higher when the index catheterization was performed by an interventional cardiologist than when it was performed by a noninterventionalist (P < 0.001).

The authors conclude, “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.”

In an interview with TCTMD, David J. Cohen, MD, MSc, of Saint Luke’s Mid America Heart Institute (Kansas City, MO), said that although it would be difficult to replicate this kind of study in the United States because databases are not as complete as under the Canadian national health system, he suspects US variability in the PCI:CABG ratio is “fairly similar.” Moreover, the proportion of interventional cardiologists performing diagnostic catheterizations is much higher in the United States, potentially favoring PCI even more.

Ad Hoc PCI an Obstacle to Informed Consent

In Dr. Cohen’s view, the practice of ad hoc PCI is a major barrier to the authors’ stated goals of “transparency and consistency.” “Ad hoc PCI deprives patients of the chance to make a fully informed decision with all the options and facts laid out in front of them,” he said. “It’s hard to inform patients [before angiography] when you don’t really know what you’re dealing with.”

Ad hoc PCI is also a major challenge to implementation of the widely recommended heart team approach, in which multiple specialists and sometimes the referring physician lay out the options for a patient. Instead, Dr. Cohen asserted, ad hoc PCI is “an unintended adverse consequence of the drive to contain costs. But it may not. You may end up doing a procedure that is not what the patient wants and may not have an ideal outcome. I’d love to be able to put that genie back in the bottle.” 

Don’t Discount Differences in Operator Skill

For his part, Ajay J. Kirtane, MD, SM, of Columbia University Medical Center (New York, NY), told TCTMD he is uneasy with the authors’ implied call for consistency in practice. “I don’t think homogenization is a good thing,” he said. “If you have operators who are really good at doing complex lesions, they should not be discouraged from doing them just because others are not as good and the bar has been set too low.”

In addition, some of what may look like overinfluence of interventionalists actually can be attributed to referral patterns, he pointed out. “Sometimes the decision on [which specialist] to send the patient to in the first place depends on the risk profiling of the patient by the referring physician,” Dr. Kirtane said. “So in effect, the decision has already been made.”

Dr. Kirtane also disputed that ad hoc PCI always precludes informed decision making, saying, “You can have good conversations with the patient and the referring [physician] ahead of time.”

In an accompanying commentary, David R. Holmes Jr, MD, and Charanjit S. Rihal, MD, of the Mayo Clinic (Rochester, MN), observe that “the striking variation” in PCI:CABG  ratios seen in the study may in part reflect patients’ expectations. [P]atients need to develop their own hierarchy of important components of the risk-benefit ratio,” they write. “One size does not fit all. Because expectations vary, the medical care team needs to identify the specific hierarchy of outcomes for each patient.”

Study Details

During the study period, 11 of the participating centers performed both PCI and CABG surgery, 1 performed PCI only, and 5 performed cardiac catheterization only. About 45% of angiograms were performed by an interventional cardiologist.

Patients’ baseline characteristics were fairly similar across the 4 ratio categories, except that those at hospitals in the highest PCI:CABG ratio category were more likely to have had a previous PCI.

2. Holmes DR, Rihal CS. Revascularization options: One size does not fit all. CMAJ. 2011;Epub ahead of print.

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