Non-invasive multislice computed tomography coronary angiography for imaging coronary arteries, stents and bypass grafts

Multislice Computed Tomography Coronary Angiography: Risk Stratification of Patients in the Perioperative Period

Multislice computed tomography coronary angiography is emerging as a reliable noninvasive method for the assessmentofcoronaryarterydisease, coronaryanatomyand cardiac function. Improvements in computed tomography technology hold the promise of replacing the standard invasive procedure of conventional coronary angiography in selected patient groups. The ability of a six-second scan to identify flow-limiting coronary artery stenoses as well as characterising coronary atheromatous plaque components provides valuable information that can assist in refining perioperative cardiovascular risk. Multislice computed tomography's high negative predictive value and high specificity for stenoses allows it to effectively rule out coronary artery disease in patients with cardiac risk factors who have non-diagnostic or equivocal noninvasive cardiac stress tests. Other uses include evaluating patients who are symptomatic following percutaneous coronary intervention, evaluating coronary artery bypass grafts and coronary stent patency, detecting coronary stenosis prior to valve surgery and assessing coronary anatomy in patients with technically difficult arterial access. Avoiding the small but definite risks of conventional coronary angiography makes cardiac computed tomography an appealing alternative. An overview of multislice computed tomography is presented with particular attention placed on its role in the risk stratification of selected patients in the perioperative period. A risk stratification algorithm is suggested.

Quality control after total arterial revascularisation: multislice computer tomography cannot replace coronary angiography

INTRODUCTION

Coronary angiography is regarded as the gold standard in evaluating graft patency, Multi-slice CT (MSCT) which enable rapid imaging of cardiac structures, including coronary arteries may be a less invasive technique. Therefore in our institution a prospective pilot study was performed combining these procedures.

PATIENTS AND METHODS

Starting from July 2004 a study was done with 13 patients. They received TAR using composite left internal thoracic artery (LITA) and left radial artery (RA) as T-graft. Intra-operative angiography was performed in these patients to confirm graft patency. Follow-up control (9-21 months) was performed with exercise Ergometry and 64 slides MSCT.

RESULT

Mean procedure time for intra-operative angiography was 13.7 +/- 7.3 min and mean fluoroscopy time was 6.2 +/- 4.6 min. In one patient, RA-marginal artery side to side anastomoses was stenosed and had to be revised. And in another, there was a kinking of the LITA and was corrected. At follow-up, exercise ergometry showed no signs of angina or ECG-changes in all patients. MSCT showed occluded radial artery grafts in two patients. In two other patients interpretation was difficult due to resolution reasons. In all patients the LITA graft was patent.

CONCLUSION

The intra-operative graft angiography can be performed in patients undergoing TAR easily. MSCT can be used for post-operative less-invasive angiography with limitations in patients with small graft/coronary diameters and arrhythmias. However, this study shows that an interdisciplinary cooperation is a new possibility toward quality control during and after TAR.

Diagnostic accuracy of 16-slice CT coronary angiography in the evaluation of coronary artery disease

Multislice CT coronary angiography (CT-CA) has emerged as a potential imaging method for coronary artery disease. This study aimed to ascertain the accuracy of 16-slice CT in the diagnosis of significant coronary stenosis (>or=50% reduction of lumen diameter). This mixed retrospective/prospective observational study compared 95 paired 16-slice CT-CA and fluoroscopic coronary angiography (FCA) sets. A cardiologist and a radiologist blinded to the FCA findings evaluated CT-CA images independently by visual estimation. Disagreement between these reporters was arbitrated by a third CT reporter (a cardiologist). A separate cardiologist blinded to CT-CA findings assessed FCA by visual estimation. Of 1,161 coronary segments assessable on FCA, 1,103 segments (95%) were assessable on CT-CA. The CT-CA correctly diagnosed 147/180 segments with significant stenoses (sensitivity = 82%) and correctly identified 874/923 coronary segments without significant stenoses (specificity = 95%). The positive and negative predictive values of CT-CA in the diagnosis of coronary segment with significant stenosis were 75 and 96%, respectively. On patient-based analysis, CT-CA correctly identified all 68 studies with at least one vessel with significant stenosis (sensitivity = 100%; specificity = 83%). The positive and negative predictive values of CT-CA in identifying patients with significant coronary stenosis were 94 and 100%, respectively. The 16-slice CT-CA showed moderately good sensitivity but very high specificity and negative predictive value in the diagnosis of significant coronary stenosis. The CT-CA would appear to be a useful 'rule-out' test for patients with low-risk profile for ischaemic heart disease.

Determining the proportion of coronary segments assessable on 16-slice CT coronary angiography: a brief report

Computed tomography coronary angiography (CT-CA) is becoming a popular non-invasive coronary imaging method. We aimed to determine the proportion of coronary segments assessable on a 16-slice CT in comparison with conventional selective coronary angiography (SCA). We identified all patients who had both 16-slice CT-CA and recent SCA (less than 12 months) from March 2004 to July 2005. Two CT reporters blinded to SCA independently classified coronary segment assessability on CT-CA. A cardiologist blinded to CT findings classified assessability of coronary segments on SCA. Data were analysed using descriptive statistics and proportion of agreement. Ninety-five study pairs were included in the analysis. Of those, 1161 coronary segments were deemed assessable on SCA and 1103 segments (95%) were also assessable on CT-CA. Nonassessable segments on CT-CA were predominantly in the distal segments and branches of coronary arteries. Reasons for nonassessability were small calibre (48.3%), motion artefacts (20.7%) and poorly reconstructed segments (22.4%). The 16-slice CT was able to assess a high proportion of but not all coronary segments. Nonassessable segments were predominantly distal segments or branches of coronary arteries. Motion artefacts due to heart-rate changes, small calibre and poorly reconstructed images were main causes of nonassessability on 16-slice CT-CA.