Diagnostic accuracy of computed tomography angiography for the detection of coronary artery disease in patients referred for transcatheter aortic valve implantation

Role of exercise cardiogoniometry in coronary artery disease diagnostics

BACKGROUND

The use of noninvasive diagnostics in coronary artery disease remains underdeveloped. To date, there is no simple and inexpensive method that can lead to a reliable diagnosis. Aside from costly and elaborate imaging techniques, exercise ECG, with its rather moderate sensitivity and specificity, is the main diagnostic method available.

METHODS

In this prospective study of 109 patients, the diagnostic value of cardiogoniometry (CGM), a three-dimensional, computer-analyzed vector cardiogram, was determined before and after physical stress, and the results were compared with those obtained from a stress test. We also investigated whether the sensitivity and specificity of the classical bicycle stress test could be increased with the addition of measurements obtained by CGM. Coronary angiography was used as a reference method.

RESULTS

CGM had a sensitivity of 39% at rest and 42% after physical stress and a specificity of 63% at rest and 57% after stress. This method was found to be markedly inferior to pre-test probability (sensitivity 53%, specificity 81%), stress ECG (sensitivity 52%, specificity 81%), and resting ECG (sensitivity 50%, specificity 64%). The efficiency of exercise ECG testing was not improved by use of CGM results.

CONCLUSION

If CGM is to be established as a viable diagnostic method in daily clinical practice, it must undergo further development.

Limits of the possible: diagnostic image quality in coronary angiography with third-generation dual-source CT

BACKGROUND

The usage of coronary CT angiography (CTA) is appropriate in patients with acute or chronic chest pain; however the diagnostic accuracy may be challenged with increased Agatston score (AS), increased heart rate, arrhythmia and severe obesity. Thus, we aim to determine the potential of the recently introduced third-generation dual-source CT (DSCT) for CTA in a 'real-life' clinical setting.

METHODS

Two hundred and sixty-eight consecutive patients (age: 67 ± 10 years; BMI: 27 ± 5 kg/m²; 61% male) undergoing clinically indicated CTA with DSCT were included in the retrospective single-center analysis. A contrast-enhanced volume dataset was acquired in sequential (SSM) (n = 151) or helical scan mode (HSM) (n = 117). Coronary segments were classified in diagnostic or non-diagnostic image quality. A subset underwent invasive angiography to determine the diagnostic accuracy of CTA.

RESULTS

SSM (96.8 ± 6%) and HSM (97.5 ± 8%) provided no significant differences in the overall diagnostic image quality. However, AS had significant influence on diagnostic image quality exclusively in SSM (B = 0.003; p = 0.0001), but not in HSM. Diagnostic image quality significantly decreased in SSM in patients with AS ≥2,000 (p = 0.03). SSM (sensitivity: 93.9%; specificity: 96.7%; PPV: 88.6%; NPV: 98.3%) and HSM (sensitivity: 97.4%; specificity: 94.3%; PPV: 86.0%; NPV: 99.0%) provided comparable diagnostic accuracy (p = n.s.). SSM yielded significantly lower radiation doses as compared to HSM (2.1 ± 2.0 vs. 5.1 ± 3.3 mSv; p = 0.0001) in age and BMI-matched cohorts.

CONCLUSION

SSM in third-generation DSCT enables significant dose savings and provides robust diagnostic image quality in patients with AS ≤2000 independent of heart rate, heart rhythm or obesity.

A systematic review and meta-analysis of multidetector computed tomography in the assessment of coronary artery bypass grafts

PURPOSE

The present meta-analysis aimed to compare the diagnostic accuracy of more recent computed tomography coronary angiography (CTCA) with invasive coronary angiography (ICA) in the assessment of graft patency after coronary artery bypass graft surgery (CABG).

MATERIAL AND METHODS

A systematic review was performed using nine electronic databases from their dates of inception to July 2015. Predefined inclusion criteria included studies reporting on comparative outcomes using ≥64 slice multidetector computed tomography (MDCT) and ICA. The primary endpoints included graft occlusion and significant graft stenosis ≥50%. Secondary analyses included the comparison of arterial versus venous graft conduits, and the use of different MDCT techniques.

RESULTS

Thirty-one studies were identified according to selection criteria, involving 1975 patients with 5364 assessed grafts. Combined assessment of stenosis and occlusion for all grafts demonstrated a sensitivity of 96.1% [95% confidence interval (CI) 94.3-97.4%] and specificity of 96.3% (95% CI 95.1-97.3%). CTCA assessment of venous grafts demonstrated higher sensitivity compared to arterial grafts, when testing for both occlusion and stenosis (97.6% vs 89.2%, p=0.004).

CONCLUSION

Results of this study demonstrated that CTCA had a relatively high pooled sensitivity, specificity and negative predictive value compared to ICA. However, patient baseline characteristics varied between studies, and the results should be interpreted with caution. Nonetheless, our results indicate that CTCA should be recognized as an accurate and non-invasive investigation for graft patency in symptomatic patients after CABG.

Cyclic changes in area- and perimeter-derived effective dimensions of the aortic annulus measured with multislice computed tomography and comparison with metric intraoperative sizing

AIMS

Multislice computed tomography (MSCT) is recommended for annular sizing prior to transcatheter aortic valve implantation (TAVI), but it remains unclear whether systolic or diastolic reconstructions should be used and whether the effective annular diameter should be derived by area or perimeter. In this study these different approaches were compared with intraoperative sizing.

METHODS

In 52 patients who were evaluated but deemed unsuitable for TAVI, the annulus was measured during conventional surgery using metric sizers (AnnOp) and compared with MSCT measurements (cross-sectional diameter derived by area [AnnAsys, AnnAdia; AnnAmean = (AnnAsys + AnnAdia)/2] and perimeter (AnnPsys, AnnPdia) in systole and diastole). Furthermore, TAVI was simulated based on AnnOp and the impact of the various MSCT approaches on sizing strategy was determined.

RESULTS

The best agreement with AnnOp [mean difference (limits of agreement)] was shown for AnnAmean [0.03 mm (-1.9 to 1.96)], whereas the strongest deviation was noted for AnnPsys [-1.08 mm (-3.01 to 0.86)]. Mean differences between systole and diastole were significant but small: 0.82 mm (3.5 %) for area- and 0.81 mm (3.3 %) for perimeter-derived measurements. Simulation of TAVI revealed the least change of strategy for AnnAmean (76.9 %) as compared with AnnPsys (53.8 %); between AnnAsys and AnnAdia sizing would have been deviant in 17.3 % due to relatively large intraindividual cyclic differences.

CONCLUSIONS

AnnAmean demonstrated the best agreement with AnnOp, whereas perimeter-derived measurements were somewhat overestimated. Despite a negligible average difference between systolic and diastolic annular values, in a subset of patients the intraindividual cyclic variability was relatively large and potentially of clinical impact.