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Coronary CT angiography associated with reduced MI incidence
In patients with suspected coronary artery disease, coronary CT angiography decreased myocardial infarction incidence while increasing coronary artery disease detection and use of secondary prevention medications compared with functional stress testing, according to research published in JAMA Internal Medicine.
“Coronary computed tomography angiography (CCTA) is a new approach for the diagnosis of anatomical coronary artery disease (CAD), but it is unclear how CCTA performs compared with the standard approach of functional stress testing,” Andrew J. Foy, MD, from the department of medicine at Penn State College of Medicine, Hershey, and colleagues wrote.
Foy and colleagues sought to determine the clinical effectiveness of CCTA for patients with suspected CAD compared with functional stress testing. The researchers conducted a systematic literature search for randomized clinical trials published between Jan. 1, 2000, and July 10, 2016, that compared the two tests and evaluated all-cause mortality, cardiac hospitalization, MI, invasive coronary angiography, coronary revascularization, new CAD diagnoses, and change in aspirin and statin prescriptions.
Researchers identified 13 eligible trials including 10,315 patients who underwent CCTA and 9,777 patients who underwent functional stress testing. Patients were followed for a mean of 18 months.
Results showed that CCTA and functional stress testing were not significantly different in death (CCTA, 1% vs. stress testing, 1.1%; RR = 0.93; 95% CI, 0.71-1.21) or cardiac hospitalization (2.7% vs. 2.7%; RR = 0.98; 95% CI, 0.79-1.21). However, CCTA reduced the incidence of MI compared with functional stress testing (0.7% vs 1.1%; RR = 0.71; 95% CI, 0.53-0.96).
Moreover, in patients in the CCTA arm, there was a significantly greater likelihood of undergoing invasive coronary angiography (11.7% vs. 9.1%; RR = 1.33; 95% CI, 1.12-1.59) and revascularization (7.2% vs. 4.5%; RR = 1.86; 95% CI, 1.43-2.43). Patients undergoing CCTA also had a greater likelihood of receiving a diagnosis of new CAD (18.3% vs. 8.3%; RR = 2.80; 95% CI, 2.03-3.87), and initiating aspirin (21.6% vs. 8.2%; RR = 2.21; 95% CI, 1.20-4.04) or statin therapy (20% vs. 7.3%; RR = 2.03; 95% CI, 1.09-3.76).
“Although these results may apply to patients with both acute and stable chest pain and suspected CAD, important gaps in the medical evidence remain,” Foy and colleagues concluded. “These gaps include (1) the presence of heterogeneous effects for CCTA compared with functional stress testing related to the variables of age, sex, baseline risk and comparator test used; (2) the risk of adverse events associated with excess invasive procedures; and (3) whether information gained from CCTA improves patient management and long-term clinical outcomes compared with functional stress testing alone when patients in both groups are managed using systematic protocols.”
In an accompanying editorial, Todd C. Villines, MD, from the Uniformed Services University of the Health Sciences, Bethesda, Md., and Leslee J. Shaw, PhD, from the Emory Clinical Cardiovascular Research Institute, Atlanta, wrote that these findings demonstrate that patients without known CAD but with acute or stable chest pain should have the option and access to undergo CCTA.
However, changes in preventive therapies likely fuel the benefits of CCTA, emphasizing that systematically pairing test findings and management is crucial, they wrote.
“Strategies to improve the specificity of CCTA, such as selective ischemia-testing, may serve to further reduce the number of patients referred to [invasive coronary angiography] following CCTA to only those most likely to benefit from revascularization,” Villines and Shaw concluded. “Ultimately, the findings by Foy et al. are intriguing and certainly require additional exploration. However, the evidence to date supports that CCTA may improve important clinical outcomes, a fact that should be shared with patients during the decision-making process regarding test choice.” – by Alaina Tedesco
Disclosures: The authors report no relevant financial disclosures.
Perspective
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This meta-analysis of randomized control trials comparing outcomes in acute or stable chest pain patients undergoing coronary CT angiography versus functional testing found no difference in mortality or cardiac hospitalization. However, coronary CT angiography was associated with an increase in new CAD diagnosis, which likely drove the associated increase in aspirin and statin use and the reduction in MIs. This reduction in MI should be viewed cautiously because some of the trials used in this meta-analysis compared coronary CT angiography plus functional testing with functional stress testing alone and thus did not compare coronary CT angiography with a functional stress testing strategy. Their stress testing arms varied among trials, with multiple modalities, such as exercise electrocardiography, stress echocardiography and stress myocardial perfusion imaging.
The sensitivity and specificity for detecting obstructive stenosis of more than 50% is significantly different for each of these functional modalities. The researchers also did not assess differences in radiation exposure in patients undergoing coronary CT angiography or functional testing. This analysis also corroborates prior studies that found that coronary CT angiography versus functional testing is associated with increased invasive procedures, risk of adverse events and associated costs. Further studies are needed to decide if coronary CT angiography improves patient management and long-term outcomes compared with functional imaging.
Perspective
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There has been increasing interest in the use of coronary CT angiography as an alternative to the well-established approach of functional stress testing when evaluating individuals with suspected coronary artery disease. Randomized clinical trials comparing these two approaches have yielded mixed results, but generally find them comparable, with no difference in clinical outcomes.
This new systematic review and meta-analysis of randomized clinical trials comparing the two diagnostic strategies found that, with one exception there was no difference in clinical outcomes with the two approaches. Compared with functional stress testing, coronary CT angiography evaluated patients had similar rates of death and similar cardiac hospitalization rates. There was a lower risk of MI, but this difference was only 0.4%. Patients being evaluated by CT angiography have more catheterizations and more revascularizations.
These findings suggest that coronary CT angiography may be a reasonable alternative to functional stress testing, with the upside of potentially greater use of cardioprotective medications but also the downside of increased use of more invasive procedures and their associated costs. The large randomized ISCHEMIA trial that is ongoing will provide further insights into the evaluation and management of patients with suspected coronary artery disease.