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Noninvasive test chosen in most cases of suspected CAD
Three out of four patients with new symptoms suggestive of CAD underwent noninvasive testing during their first examination, according to results of a real-world, retrospective, single-center study.
Of those referred for a noninvasive test, approximately one-fifth had significant CAD, compared with one-third of those who had been referred for an invasive test, researchers found.
According to the study background, European Society of Cardiology, American College of Cardiology and American Heart Association guidelines for angina management call for patients with a high pretest risk for CAD to be referred directly for invasive coronary angiography, whereas those without a high pretest risk should undergo a noninvasive test first.
Researchers investigated the daily use of diagnostic tests in clinical practice for patients with stable angina suggestive of CAD.
They analyzed 1,069 consecutive patients who presented during a 1-year period with new symptoms suggestive of CAD and were referred for exercise stress testing, coronary CTA, single-photon emission CT or invasive coronary angiography.
Invasive vs. noninvasive
Ajda Zorlak, MD, from the department of cardiology at Odense University Hospital, Odense, Denmark, and colleagues found that 75% of patients were first referred to a noninvasive test (exercise stress test, 37; coronary CTA, 450; SPECT, 310), with the remaining 25% directly referred for invasive coronary angiography.
The invasive testing group had a higher pretest probability than the noninvasive group (48% vs. 26%; P < .0001) and were more likely to be older (P < .0001), be a current or former smoker (65% vs. 57%; P = .03), have diabetes (20% vs. 10%; P < .0001) and be on antihypertensive medications (66% vs. 49%; P < .0001) or statins (47% vs. 29%; P < .0001), according to the researchers.
Patients in the invasive testing group were also more likely to have test results indicative of significant CAD than those in the noninvasive testing group (31% vs. 18%; P < .0001), they found.
CTA vs. SPECT
When the researchers analyzed those initially tested via was coronary CTA vs. SPECT, downstream testing (CTA, 16%; SPECT, 17%) and revascularization rate (CTA, 20%; SPECT, 9%) did not differ between the groups. Those tested via SPECT had higher pretest probability (29% vs. 24%; P = .001) and mean radiation dose (11 mSv vs. 9 mSv) than the CTA group, Zorlak and colleagues wrote.
“[Noninvasive testing] may be beneficial and results in a more effective risk stratification allowing identification of those patients who would be most likely to gain from [invasive coronary angiography] and, thereby, ideally limit the use of [invasive coronary angiography] in patients who do not have obstructive CAD,” they wrote.
Zorlak and colleagues added that one explanation for the low revascularization rates is a recent substantial increase in the use of both noninvasive and invasive examinations. “If the prevalence of CAD is unchanged, this will decrease the number of positive findings,” they wrote. “Thus, we have to consider if the current practice will entail an overuse of noninvasive and invasive examinations leading to the inefficiency.” – by Erik Swain
Disclosure: The researchers report no relevant financial disclosures.