Coronary Heart Scans highly accurate for artery narrowings – American Journal of Cardiology

Multidetector CT coronary angiography accurately detects significant stenoses October 27, 2010 — NEW YORK (Reuters Health) – Multidetector computed tomography (CT) coronary angiography detects significant stenoses with a high degree of accuracy, researchers from Australia report in the October 1 American Journal of Cardiology. “Our study demonstrates that latest generation 320-slice CT scanners provide very high diagnostic accuracy not only in the standard setting but also in the presence of rhythm abnormalities and in small caliber coronary vessels,” Dr. Sujith K. Seneviratne from Monash University, Melbourne, told Reuters Health in an e-mail. “Invasive angiography will, however, continue to play an important role in patients with high risk for coronary artery disease and in confirming and determining the treatment options in patients whose coronary disease has already been identified by noninvasive coronary angiography.” Dr. Seneviratne and colleagues evaluated the diagnostic accuracy of 320-detector row CT in the detection of significant coronary artery stenoses in 63 patients with no known coronary artery disease who underwent CT and invasive coronary angiography within 35 days (between procedures). Fifty-seven patients were in sinus rhythm and six were in atrial fibrillation at the time of CT imaging. Multidetector CT correctly identified 61 of 70 significant stenoses found on invasive coronary angiography. The missed lesions were because of poor signal-to-noise ratio (four lesions), motion artifact (two lesions), severe calcification (one lesion), and possibly due to the small caliber of the affected arteries (two lesions). Multidetector CT diagnosed 23 stenoses that turned out to be false-positive findings; all of these findings were in the presence of poor image quality. Compared with invasive coronary angiography, then, multidetector CT coronary angiography was 89% sensitive and 95% specific for detecting significant stenoses on a per-vessel basis and 94% sensitive and 87% specific on a per-patient basis. Positive predictive value was 82% and negative predictive value was 97% on a per-vessel basis. Only 17 of 973 segments (2%) in nine patients proved to be nondiagnostic, to the extent that a significant stenosis could not be confidently identified or excluded. Post hoc subgroup analyses suggested that per-segment diagnostic accuracy was not influenced by small vessel diameter, the presence of atrial fibrillation, or prospective ECG triggering, whereas moderate to severe calcification could lower specificity and increase sensitivity compared to vessels with no or minimal calcification. “Nearly 20-30% of all invasive angiography performed for investigation of chest pain ultimately returns a diagnosis of ‘no significant coronary stenoses,’ ” Dr. Seneviratne said. “Cardiac CT has the potential to substantially reduce the number of angiography performed in this group of low to intermediate risk patients with its very high negative predictive value.” “This method is most useful in patients who have chest pain at low-to-intermediate risk for an acute coronary syndrome,” Dr. Seneviratne explained. “CT angiography obviates the need for invasive angiography in a large proportion of these patients with potential for substantial cost savings, significant reduction in procedure-related complications, and improved patient satisfaction.” “Noninvasive coronary angiography in its current form is not able to supplant invasive angiography, predominantly due to its limited spatial and temporal resolution compared to selective x-ray angiography,” Dr. Seneviratne added. Source: Am J Cardiol 2010. Last Updated: 2010-10-26 16:32:16 -0400 (Reuters Health) By Will Boggs, MD