Abstract 2413: 64-Slice Coronary Computed Tomography Angiography Detects a High Prevalence of Obstructive, Non-Calcified Plaques in Symptomatic Patients and Zero Calcium Score
Background. 64-slice coronary CTA (CorCTA) allows imaging of calcified and non-calcified coronary plaques. Coronary artery calcium (CAC) has been validated in asymptomatic and symptomatic patients to detect coronary disease and predict prognosis. The incremental value of CorCTA in symptomatic patients with CAC of 0 is unknown.
Methods. 159 consecutive patients without prior revascularization referred for CorCTA for symptoms suggestive of myocardial ischemia were included in the retrospective analysis. Clinical data was available on 117 patients (mean age: 57.9; males: 45%). CorCTA parameters were: slices 32x2, detector width 0.6mm, rotation time 370ms, pitch 0.24 mm/rotation, tube voltage 120kV, using timing bolus. CAC was expressed as Agatston score. Coronary artery stenoses were determined semi-quantitatively (mild<30%, intermediate 30 –70%, obstructive>70% luminal stenosis). Demographics, clinical data, invasive X-ray angiography (XRA) and CorCTA results were extracted from charts retrospectively.
Results. Of 117 patients with clinical data, Framingham risk factors were: hypertension 75 (64%), diabetes 20 (17%), hyperlipidemia 82 (70%), tobacco use 28 (24%). 58 patients (36%) had CAC of 0. Of these, 5 (9%) had obstructive, 1 (2%) intermediate, 8 (14%) mild and 44 (75%) no luminal stenoses by CorCTA. 101 patients (64%) had positive CAC. Of these, 32 (32%) had obstructive, 26 (26%) intermediate, 37 (37%) mild and 6 (5%) no luminal stenoses. XRA confirmed the severity of stenosis in 5 of 6 patients with CAC of 0 and obstructive/intermediate stenosis on CorCTA (Table⇓).
Conclusion. In patients with symptoms suggestive of myocardial ischemia, CAC of 0 does not reliably exclude obstructive coronary stenoses; CorCTA is critical to identify intermediate/obstructive non-calcified plaques in as many as 11%. These patients need referral for XRA. Negative CAC with negative CorCTA reliably exclude significant CAD and can justifiably spare XRA.