Variability in CAD detection questioned in invasive testing study

When clinicians are looking for stable ischemic heart disease and obstructive coronary heart disease, are they overusing invasive methods? A group of researchers wondered how frequently angiographies are diagnosing obstructive coronary heart disease. The answer: is it varies.  

Concerns about invasive angiography include some risk to the patient and a high cost. Both factors drove Harindra C. Wijeysundera, MD, PhD, of the Schulich Heart Center, Sunnybrook Health Sciences Center, and the University of Toronto, and colleagues to take a critical look at how angiographies were being performed. The study appeared in the Sept. 2 issue of Circulation: Cardiovascular Quality and Outcomes.

Eighteen hospitals that took part in a network based in the Ontario province of Canada provided data between October 2008 and September 2011. Collectively, they provided 60,986 patient cases.

Of the total number of angiographies performed, a little more than half yielded positive results for obstructive coronary artery disease (CAD) (52 percent). Across the network, individual hospitals varied in detection rate, some as low as 37.3 percent of the procedures confirming obstructive CAD, some as many as 69.2 percent.

The differences in diagnosis could be broken down into hospital types, physician types and referral types. Of the three hospital types, the most obstructive CAD results came from full service hospitals (55 percent), followed by stand-alone percutaneous coronary intervention (PCI) centers (48 percent).

Diagnostic only centers were 39 percent less likely to diagnose patients with CAD.

Physicians who were interventionalists diagnosed 57 percent of their patients with obstructive CAD through angiography, as opposed to 48 percent of patients who underwent the same procedure at the hands of an invasive physician. Odds of an invasive physician diagnosis of obstructive CAD was 0.85.

Interventionalists also had a larger proportion of severe CAD (11.2 percent) as opposed to invasive physicians who found only 9.2 percent. This in turn, led to almost 10 percent more revascularizations in patients of interventionalists than invasive physicians.

Self-referral – where physicians referred patients to themselves for angiographies – had the lowest frequency of coronary artery disease diagnosis. Odds of self-referral leading to an obstructive CAD diagnosis were 0.89. Of the total population of patients, 32 percent were self-referral; some hospitals having a rate of 4.8 percent, others as high as 74.8 percent.

Preprocedural testing added another dimension to this data. A total of 59.8 percent of diagnostic centers used preprocedural testing before angiography, as opposed to 55.8 percent of full service hospitals. Non-self-referring clinicians ordered more preprocedural tests (56.9 percent) than self-referring clinicians (52.9 percent). Interventional cardiologists, meanwhile, ordered more preprocedural tests than invasive cardiologists (57.8 percent vs 52.2 percent)

Wijeysundera et al noted that the patterns revealed by this study can be applied to directing quality improvements to care and reduce burden of unnecessary invasive testing.