CMAJ: PCI-CABG variability linked to physician preference, hospital

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The physician performing an index catheterization and the treating hospital were strong independent predictors of revascularization treatment, according to a study published online Dec. 12 in the Canadian Medical Association Journal. In an accompanying editorial, the authors suggested that patient preference also may influence the threefold variation found in the ratio of PCI and CABG.

Jack V. Tu, MD, PhD, of the Institute for Clinical Evaluative Sciences in Toronto, and other members of the Cardiac Care Network of Ontario’s Variations in Revascularization Practice in Ontario Working Group set out to assess the scope and factors for variation in PCI vs. CABG for patients undergoing revascularization for coronary artery disease. Unpublished data in 2006 had shown an increase in the PCI:CABG ratio in cardiac centers in Ontario as well as threefold variation, they wrote.

“This degree of variation has raised concerns among some policy-makers and clinicians as to why such striking variations exist in Ontario’s universal healthcare system,” they explained.

For their analysis, Tu and colleagues conducted a retrospective cohort study based on a random sampling of 8,972 patients who underwent an index cardiac catheterization at one of 17 hospitals in Ontario between April 2006 and March 2007. The hospitals were then categorized into one of four groups based on a PCI-to-CABG ratio: low (less than 2); low-median (2 to 2.7); medium high (2.8 to 3.2) and high (more than 3.2).

The researchers used the Cardiac Care Network of Ontario’s master coronary angiography and procedural PCI and CABG databases plus clinical information from hospital charts to identify PCI or CABG procedures that were performed within 90 days of the index catheterization.

They found a threefold variation in ratios across four hospital groups and a fivefold variation in ratios across the individual hospitals. However, baseline characteristics of patients were similar across all groups.

They reported that coronary anatomy was the strongest predictor for a choice of PCI, followed by clinical indication for the procedure and then the treating hospital. The majority of patients with single-vessel disease underwent PCI and patients with left main artery disease most often underwent CABG.

But treatment for patients with non-emergent multivessel disease was variable. Tu and colleagues found a strong correlation between any single hospital’s PCI:CABG ratio and the hospital’s overall PCI:CABG ratio. They identified physician preference by the cardiologist who performed the index catheterization and hospital culture as key factors for the variation in patients who could be recommended for either procedure.

“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,” they wrote. “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.”

They noted that only 4 percent of cases were discussed in cardiologist-surgeon case conferences, and recommended greater transparency, consistency in decision-making and a multidisciplinary team approach be used for patients who could receive either procedure.

In an accompanying editorial, David R. Holmes Jr., MD, and Charanjit S. Rihal, MD, both of the department of cardiovascular diseases at Mayo Clinic in Rochester, Minn., pointed out that physician experience may play a role in the choice of one procedure over the other. They argued that an interventional cardiologist trained to treat more complex cases may choose PCI, while a less experienced interventional cardiologist may recommend CABG surgery.

Patients may also have a preference for one procedure over the other, they wrote. “For some patients, prolonging life is most critical; for others, avoiding surgery is paramount,” Holmes and Rihal proposed. “One size does not fit all. Because expectations vary, the medical care team needs to identify the specific hierarchy of outcomes for each patient.”

They added that physicians also must ensure that patients are well informed before choosing among the revascularization options, they concluded.