Diagnostic role of coronary calcium scoring in the rapid access chest pain clinic: prospective evaluation of NICE guidance.

BACKGROUND: Coronary artery calcium (CAC) imaging by unenhanced computed X-ray tomography (CT) is recommended as an initial diagnostic test for patients with stable chest pain symptoms but a low likelihood (10-29%) of underlying obstructive coronary artery disease (CAD) after clinical assessment. The recommendation has not previously been tested prospectively in a rapid access chest pain clinic (RACPC). METHODS: We recruited 300 consecutive patients presenting with stable chest pain to the RACPC of three hospitals. All patients underwent CAC imaging, followed by invasive coronary angiography (ICA) in patients with CAC ≥ 1000 Agatston units (Au) and CT coronary angiography (CTCA) in those with CAC <1000. Patients with 50-70% stenosis on CTCA underwent myocardial perfusion scintigraphy (MPS) while those with ≥ 70% stenosis underwent ICA. Obstructive CAD was defined as ≥ 70% stenosis on ICA or the presence of inducible ischaemia on MPS. Patients were followed up clinically for a mean of 17 (SD 6) months. RESULTS: The mean patient age was 60.6 (SD 9.6) years and 48% were males. Obstructive CAD was found in 56 (19%) patients, of whom 42 (14%) underwent revascularization. CAC was zero in 131 (44%) patients, of whom two (1.5%) had obstructive CAD and one (0.8%) underwent revascularization. The sensitivity, specificity, negative predictive value, and positive predictive value of CAC ≥ 1 for detection of obstructive CAD were 96, 53, 32, and 98%, respectively. None of the 57 patients with low pre-test probability of CAD and zero CAC had obstructive CAD or suffered a cardiovascular event during the follow-up. CONCLUSION: Patients with stable chest pain symptoms but a low likelihood of CAD can safely be diagnosed as not having obstructive CAD in the absence of detectable coronary calcification by unenhanced CT. Patients with CAC >400 Au have a high prevalence of obstructive CAD and further investigation with ICA or functional imaging may be warranted rather than CTCA. These findings support NICE guidance for the investigation of stable chest pain. ClinicalTrials gov identifier: NCT01464203.

Time course and extent of collateral channel recruitment during coronary angioplasty.

OBJECTIVES: To assess the extent and timing of recruitment of collateral channels during coronary angioplasty in patients without spontaneous collaterals at diagnostic angiography. SETTING: The extent of collateral channel recruitment during coronary angioplasty is variable and its contribution to myocardial protection is not well established. The functional significance of collaterals recruited during balloon occlusion remains in question. PATIENTS: Collateral channels were assessed in 16 patients by contralateral injection at 30, 60 and 90 s into each of four 90 s inflations and by a 0.014 " Doppler guide wire distal to the lesion. RESULTS: Angiographic collateral recruitment was evident in 11 out of 16 patients (71%), but in only four (24%) by intracoronary Doppler. Grade I collaterals were present in seven patients, grade II in three and grade III in two. Collaterals were evident angiographically by 30 s in 10 out of 11 patients, with no progressive recruitment during subsequent inflations. In the four patients with Doppler evidence of collateral flow there were no differences in any flow velocity parameters with successive inflations. There was no difference in either maximum ST segment shift or time to 2 mm ST segment elevation between successive inflations. CONCLUSIONS: Collateral channel recruitment is variable between patients and appears maximal early in the first inflation. The lack of incremental recruitment of collaterals together with low or absent evidence of flow by Doppler wire suggests that these channels do not make a major contribution to myocardial protection in this setting.