Coronary CTA accurately identifies significant coronary artery stenosis

Coronary CTA accurately identifies significant coronary artery stenosis By Reuters Health February 17, 2012 — NEW YORK (Reuters Health) – Coronary CT angiography (CCTA) is more accurate than stress testing in identifying individuals with significant coronary artery obstruction, according to a report in the February 14 Journal of the American College of Cardiology. “Our study findings suggest that in low-to-intermediate risk patients that have already undergone stress testing and the results are either equivocal or there is discordance between the results and clinical presentation, CCTA would be a reasonable strategy to further risk stratify and select patients that need invasive assessment,” said Dr. Kavitha M. Chinnaiyan from William Beaumont Hospital in Royal Oak, Michigan. “Moreover, normal findings on CCTA would suggest that the patient would not need any further cardiac testing for five to seven years, the ‘warranty period’ of this test,” she told Reuters Health by email. Dr. Chinnaiyan and colleagues evaluated the relationship between clinical assessment, stress test results, and extent of coronary artery disease on CCTA in a statewide registry (the Advanced Cardiovascular Imaging Consortium). The final study group included nearly 6,200 patients without known coronary artery disease. Just under a fifth of the patients had obstructive coronary artery disease (> 50% stenosis) by CCTA; 77% of asymptomatic patients had normal coronary arteries or nonobstructive coronary artery disease compared to 82% of symptomatic patients (p [ 0.0001). Stress test results did not independently predict obstructive coronary artery disease. In fact, Framingham Risk Score alone provided the same predictive ability as adding stress test results in this study group. Among the 621 patients who underwent invasive coronary angiography, there was no significant relationship with stress test results, but CCTA results were strongly predictive of obstructive coronary artery disease (odds ratio, 9; p [ 0.001). The positive predictive value and negative predictive value for > 50% stenosis on CCTA compared with the invasive test were 71% and 79%, respectively. In multivariable analysis, the degree of stenosis on CCTA was the strongest additional predictor of obstructive coronary artery disease on invasive coronary angiography beyond the Framingham Risk Score, whereas stress test results had no incremental value over clinical assessment. “Although our findings strongly suggest that CCTA works well as a gatekeeper to invasive coronary angiography in patients who need adjudication of stress test results, the best initial strategy for workup of coronary artery disease (CAD) is not yet clearly defined,” Dr. Chinnaiyan said. “It would seem reasonable to use CCTA in certain populations as the first test, for example, low-to-intermediate risk individuals with acute chest pain. In such patients, skipping stress tests would seem reasonable and has been shown to improve time to diagnosis and expedited triage.” “For patients with chronic symptoms of CAD, large randomized controlled trials, such as PROMISE will shed more light on the best initial strategy,” Dr. Chinnaiyan added. “It must be remembered that CCTA is a radiation-based test. Until recently, monitoring cumulative radiation doses in patients undergoing multiple tests was not the norm. However, with all the attention given to this growing problem, we need to become cognizant about the issue of cumulative dose with layered testing. Moreover, the costs of layered testing are going to mandate that we use the tests available judiciously.” “The study is interesting, revealing, stimulates our diagnostic thinking, and should prompt a prospective well-designed study in which the need for adjudication with a second test, in case of diagnostic uncertainty after a initial diagnostic test, is based on the post-test likelihood of CAD, with prespecified levels of diagnostic uncertainty, thereby providing more support to judicious referral to another test to increase the diagnostic yield of invasive coronary angiography to detect obstructive disease,” write Dr. Pim J. de Feyter and Dr. Koen Nieman from Erasmus Medical Center in Rotterdam, the Netherlands, in a related editorial.