Most Patients Undergoing Diagnostic Angiography Before Noncardiac Surgery Are Asymptomatic

Data from a large US registry show that most patients undergoing diagnostic catheterization as part of a cardiac assessment prior to noncardiac surgery are asymptomatic and approximately one in five individuals have stable angina symptoms. Those referred for coronary angiography did have a high prevalence of cardiovascular risk factors, and most had a positive stress test, report investigators.

In total, 48.1% of individuals referred to the cath lab for a diagnostic workup had evidence of obstructive coronary disease, and nearly one in four  in the entire cohort was referred for coronary revascularization with PCI or CABG surgery, according to a study published March 28, 2016, in JAMA: Internal Medicine.

Speaking with TCTMD, senior investigator Rajesh Swaminathan, MD (Weill Cornell Medical College, New York, NY), said the preoperative guidelines recommend a “stepwise” approach for clinical risk assessment, including the selective use of noninvasive imaging, but that routine coronary angiography before noncardiac surgery is not recommended.

“These are patients who are undergoing a workup for cardiac risk assessment prior to going for noncardiac surgery,” he said. “We have algorithms and guidelines in place to guide us with what we should do with these patients. It’s based on their risk factors, their functional capacity, and the results of the stress tests and EKGs. A lot of patients are low risk for surgery based on these things, and they can proceed directly to surgery without getting further cardiac workup.”

Noninvasive testing to look for potential myocardial ischemia might identify individuals considered intermediate or high risk for surgery, however, which would then lead to further diagnostic testing as part of the preoperative risk assessment. If these noninvasive tests are abnormal, the clinical revascularization guidelines state that cardiac catheterization could be considered, said Swaminathan.

Data From the NCDR CathPCI Registry

Using data from the National Cardiovascular Data Registry (NCDR) CathPCI Registry, the researchers wanted to gain some insight into the type of patients referred to the catheterization lab and the resulting outcomes following angiography. Between 2009 and 2014, they identified 194,444 patients from 1,046 clinical centers who underwent coronary angiography prior to noncardiac surgery. Among these patients, nearly 80% were overweight or obese, and 40% had diabetes mellitus.

Of the patients undergoing angiography, 60.6% were asymptomatic, although 57.8% of patients were taking antianginal medications within 2 weeks of the diagnostic angiography. In total, 65% of patients undergoing angiography underwent noninvasive stress testing, and 86% of these individuals had a positive result.

Overall, 48% of individuals referred to the cath lab, or 93,447 patients, had obstructive coronary artery disease. Following angiography, coronary revascularization with PCI or CABG surgery was recommended in 23.8% of individuals in the entire cohort, including 15.6% for PCI and 8.2% for surgery. Among asymptomatic patients, 23.1% were referred for coronary revascularization, as were 48.3% of individuals with obstructive disease. For the 27,838 who underwent PCI based on the angiographic findings, 85.5% of the cases were classified as elective and 14.3% as urgent. Overall, just 1.3% of lesions were in the left-main artery and 13.8% were in the proximal left anterior descending artery.   

“The role of the cath lab is where there can be some controversy,” said Swaminathan. “Basically, if you’re intermediate or high risk, then a lot of patients are referred for angiography to clearly define their coronary anatomy and to see if they really have obstructive disease that is high risk. After you do the diagnostic portion, the question is what should you do after that? Some of these patients are getting revascularization, either with stents or being recommended for CABG. Some of the patients are medically treated to get them through surgery, and then [PCI or CABG] is done afterwards.”

He added that among the patients with obstructive coronary disease, revascularization was recommended in approximately half, meaning the other half received medical therapy prior to noncardiac surgery. “A lot of people are doing different things,” said Swaminathan. “They’re not quite sure what to do. This is an issue. It’s a dilemma.”

Is This COURAGE Déjà Vu?

In an editorial, David Brown, MD (Washington University School of Medicine, St. Louis, MO), and Rita Redberg, MD (University of California, San Francisco), draw attention to the CARP (Coronary Artery Revascularization Prophylaxis) study, a trial of 510 patients randomized to revascularization (or not) prior to elective vascular surgery. After a median of 2.7 years, there was no mortality difference between the two groups, as well as no difference in rates of MI. That trial, which included higher-risk patients such those with a prior MI and triple-vessel disease, “clearly showed a strategy of preoperative coronary artery revascularization prior to elective vascular surgery does not improve short- or long-term clinical outcomes,” write Brown and Redberg.

For the editorialists, continuing to perform elective PCI prior to noncardiac surgery is reminiscent of the situation surrounding the COURAGE trial, a randomized trial that showed no reduction in the rate of death or MI with PCI compared with medical therapy in patients with stable coronary disease. The reason for the resistance to changing practice in light of evidence is likely the result of several factors, they state, including referral bias, financial gain, and perception of the patient and physician of what can be gained by the procedure.

“The persistence of unnecessary and potentially harmful PCI procedures should stimulate efforts to enhance translation and dissemination of the clinical science and improve compliance with these guidelines,” write Brown and Redberg.

For Swaminathan, there is some truth to the oculostenotic reflex, but he emphasized the patient population studied in their analysis. The individuals were all enrolled in the CathPCI Registry, a select group of patients who likely all had a prior cardiac history. He cautioned against the conclusion that physicians are doing unnecessary procedures.

“I think in the big scheme of things,” said Swaminathan, “it’s millions of patients going for clearance [prior to surgery], and we’re seeing less than a quarter of these actually had a recommendation [for revascularization]. I think that’s important, to keep the scope in mind. And when we do PCI for these patients, it’s not that we’re doing an unnecessary procedure. This is a collaborative decision made between the interventionalist, the referring physician, anesthetist, the surgeon, and also the patient.”

He added that the NCDR data do not include information on the type of noncardiac surgery the patient was scheduled to undergo and this is one of the limitations of their analysis. The nature of the upcoming surgery could have impacted the decision to proceed to coronary revascularization, he said.

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