CTA Not Justified to Risk Stratify Patients Without Chest Pain

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In patients without chest pain, assessment of coronary artery disease (CAD) by coronary computed tomographic angiography (CTA) does not add clinically meaningful value compared with what is known from Framingham risk factors plus coronary artery calcium scoring, according to findings from an international, multicenter study of patients published online June 9, 2012, ahead of print in Circulation.

Hyuk-Jae Chang, MD, PhD, of Yonsei University College of Medicine (Seoul, South Korea), and colleagues evaluated data from CONFIRM (COronary CT Angiography EvaluatioN For Clinical Outcomes: An InteRnational Multicenter Registry) on the 7,590 patients without chest pain who underwent coronary CTA and calcium scoring at 12 centers in 6 countries between February 2003 and December 2009. None of the patients had prior MI or coronary revascularization. Median follow-up duration was 24 months.

The CONFIRM registry is intended to evaluate associations between coronary CTA findings and their ability to predict mortality and major adverse cardiac events. Recently, strong prognostic value of coronary CTA in the overall registry has been demonstrated (Chow BJ. Circ Cardiovasc Imaging. 2011;4:463-472).

CTA Shows Negligible Effect

At 2.5 years, Kaplan-Meier analysis showed that overall cumulative mortality rate was 2.3%. Mortality was higher for those with obstructive CAD compared with those without (4.1% vs. 1.7%; log-rank P < 0.001). The cumulative rate of nonfatal MI and all-cause death was 2.2% overall. Again, outcomes were worse in patients with obstructive CAD than those without (4.6 % vs. 1.6%; log-rank P < 0.001).

After risk adjustment, patients with obstructive multivessel or left main CAD had higher rates of death and the composite of nonfatal MI/all-cause death than those without obstructive disease (P < 0.05 for both). Coronary CTA independently predicted future death/nonfatal MI for patients with obstructive 2-vessel disease (HR 5.91; 95% CI 2.53-13.80; P < 0.001) and either obstructive 3-vessel or left main CAD (HR 7.11; 95% CI 2.73-18.51; P < 0.001). Plaque burden also was independently associated with future death, as measured by the modified Duke prognostic index and segment stenosis score (P ≤ 0.001 for trend for both).

Calcium scoring and CTA each improved the performance of the Framingham risk score for death and for nonfatal MI/all-cause death (P value < 0.05 for all), but the added discriminatory value was more pronounced with calcium scoring and when looking at the composite endpoint. The addition of coronary CTA to a model using the Framingham risk score and calcium scoring led to a significant improvement in predicting the composite (P < 0.001), as did adding it to individual risk factors plus calcium scoring (P = 0.003).

However, the net reclassification improvement resulting from the addition of coronary CTA to standard risk factors and calcium scoring was negligible. According to the study authors, the findings suggest that despite an inability to directly visualize the coronary arteries, calcium scoring provides “robust prognostic information” that is useful for identifying patients without chest pain who are at risk for future events.

“Considering the potential population-based radiation burden, use of iodinated contrast, and greater cost of [CTA] over [calcium scoring], the evidence that [CTA] offered in this study is not enough to justify [use of the test] for risk stratification in [a] population without chest pain syndrome,” the study authors write.

 

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Source:
Cho I, Chang H-J, Sung JM, et al. Coronary computed tomographic angiography and risk of all-cause mortality and non-fatal myocardial infarction in subjects without chest pain syndrome from the CONFIRM Registry (COronary CT Angiography EvaluatioN For Clinical Outcomes: An InteRnational Multicenter Registry). Circulation. 2012;Epub ahead of print.

 

 

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