CTA Charts Prognosis Even in Stable Patients Without Typical Risk Factors

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Computed tomographic angiography (CTA) can help predict long-term risk in stable patients with suspected coronary artery disease (CAD) but no modifiable risk factors, according to an observational study published online February 19, 2013, ahead of print in Radiology.

Jonathon Leipsic, MD, of St. Paul’s Hospital (Vancouver, Canada), and colleagues culled the records of 5,262 patients with suspected CAD and without risk factors such as hypertension, dyslipidemia, diabetes, or smoking. Data were obtained from the CONFIRM registry, which was conducted at 12 sites in 6 European, North American, and Asian countries.

Patients were either asymptomatic (36.29%) or presented with chest pain that was atypical (40.69%), noncardiac (12.04%), or typical (10.99%). The majority had either low (36.65%) or intermediate (58.62%) pretest likelihood of CAD. Approximately 30% had family histories of premature CAD.

Events Rise with More Obstructive CAD

CTA showed nonobstructive CAD in 27% of patients and obstructive CAD (defined as > 50% stenosis) in 12%. Over follow-up of 2.3 ± 1.2 years, 106 (2%) experienced the primary endpoint of MACE (defined as death, nonfatal MI, unstable angina, and late TVR after 90 days). Patients with obstructive CAD were more likely to die, experience MI, or require late TVR than those with either nonobstructive CAD or normal arteries (table 1).

Table 1. Event Rates by Presence of CAD on CTA

Multivariable adjustment for baseline risk, age, and sex linked obstructive CAD with higher likelihood of MACE on a per-patient and per-lesion basis, demonstrating a dose-response relationship between MACE risk and CAD severity (table 2).

Table 2. MACE Risk for CAD vs. Normal Arteries on CTA

Obstructive disease elevated MACE risk irrespective of whether patients were symptomatic (adjusted HR 11.9; 95% CI 4.81-29.6; P < 0.0001) or asymptomatic (adjusted HR 6.3; 95% CI 2.4-16.7; P = 0.0002), and whether family history of premature CAD was reported (adjusted HR 8.0; 95% CI 2.0-31.9; P = 0.003) or not (adjusted HR 7.2; 3.7-13.8; P < 0.0001). Nonobstructive disease paired with family history also increased the risk of MACE (adjusted HR 4.6; 95% CI 1.2-17.8; P = 0.0281).

“The results of the present study support the use of anatomic imaging with coronary CT angiography as a potentially effective method to discriminate individuals who do versus do not have CAD and who may benefit from more intensive medical and/or interventional therapy,” the researchers conclude, noting that prospective studies now appear warranted. However, they stress that the findings “are not intended to suggest modification of current appropriate use criteria but to simply provide an understanding of the prevalence of disease and its prognostic value in this unique patient population.”

CTA Intended for Symptomatic Patients

Dr. Leipsic told TCTMD in a telephone interview that the researchers are “certainly not advocating [CTA in asymptomatic patients] without risk factors, just to screen them.”

Even so, the study does offer lessons for clinical practice. “What it would highlight to me is that when you have a patient with chest pain—even if it’s atypical or if they don’t have cardiovascular risk factors—that CAD detected on CT is strongly prognostic and I think important,” he said, adding that the amount of obstructive disease in this population is “not inconsequential.”

In patients with atypical but nonacute chest pain, the “traditional algorithm would be either nothing or a treadmill, and treadmills are reasonable but they don’t have very high diagnostic accuracy for detecting coronary disease. I think CT can answer the first important question for this patient with vague pain: Do they or do they not have coronary atherosclerosis?” Dr. Leipsic said, adding, “From there you can make a decision about [how to proceed]. Equally important—if the study is entirely negative, then the patient has a very good prognosis.”

More Plaque Equals More Events

In a telephone interview with TCTMD, Robert S. Schwartz, MD, of the Minneapolis Heart Institute Foundation (Minneapolis, MN), said that the study confirms that, in patients without other modifiable risk factors, “Surprise, surprise: plaque volume is related to event likelihood.”

“It’s one more brick in the building. It’s good to know,” he commented. While it only adds “incremental” information, the study is still important, Dr. Schwartz emphasized. “You still have people who don’t understand this very simple concept [of plaque raising risk] that intuitively sounds right. Now it’s been proven multiple times over.”

Source:

Leipsic J, Taylor CM, Grunau G, et al. Cardiovascular risk among stable individuals suspected of having coronary artery disease with no modifiable risk factors: Results from an international multicenter study of 5262 patients. Radiology. 2013;Epub ahead of print.

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