M. Leung

Transluminal Attenuation Gradient in Coronary Computed Tomography Angiography Is a Novel Noninvasive Approach to the Identification of Functionally Significant Coronary Artery Stenosis: A Comparison With Fractional Flow Reserve

OBJECTIVEnThe purpose of this study was to assess the diagnostic accuracy of TAG320 in predicting functional stenosis severity evaluated by fractional flow reserve (FFR).nnnBACKGROUNDnCoronary computed tomography angiography (CCTA) has limited specificity for predicting functionally significant stenoses. Recent studies suggest that contrast gradient attenuation along an arterial lesion, or transluminal attenuation gradient (TAG), may provide assessment of functional significance of coronary stenosis. The use of 320-detector row computed tomography (CT), enabling near isophasic, single-beat imaging of the entire coronary tree, may be ideal for TAG functional assessment of a coronary arterial stenosis.nnnMETHODSnWe assessed the diagnostic accuracy of TAG320 using 320-row CCTA with FFR for the evaluation of functional stenosis severity in consecutive patients undergoing invasive coronary angiography and FFR for stable chest pain. The luminal radiological contrast attenuation (Hounsfield units [HU]) was measured at 5-mm intervals along the artery from ostium to a distal level where the cross-sectional area decreased to <2.0 mm(2). TAG320 was defined as the linear regression coefficient between luminal attenuation and axial distance. Functionally significant coronary stenosis was defined as ≤0.8 on FFR.nnnRESULTSnIn our cohort of 54 patients (age 62.7 ± 8.7 years, 35 men, 78 vessels), TAG320 in FFR-significant vessels was significantly lower when compared with FFR nonsignificant vessels (-21 [-27; -16] vs. -11 [-16; -3] HU/10 mm, p < 0.001). On receiver-operating characteristic analysis, a retrospectively determined TAG320 cutoff of -15.1 HU/10 mm predicted FFR ≤0.8 with (a bootstrapped resampled) a sensitivity of 77%, specificity of 74%, positive predictive value of 67%, and negative predictive value of 86%. The combined TAG320 and CCTA assessment had an area under the curve of 0.88. There was incremental value of adding TAG320 to CCTA assessment for detection of significant FFR by Wald test (p = 0.0001) and integrated discrimination improvement index (0.11, p = 0.002).nnnCONCLUSIONSnAssessment of TAG320 with a 320-detector row CT provides acceptable prediction of invasive FFR and may provide a noninvasive modality for detecting functionally significant coronary stenoses. Combined TAG320 and CCTA assessment may have incremental predictive value over CCTA alone for detecting functionally significant coronary arterial stenoses; however, larger studies are required to determine the benefit of combined TAG320 and CCTA assessment.

Diagnostic accuracy of combined coronary angiography and adenosine stress myocardial perfusion imaging using 320-detector computed tomography: pilot study.

AbstractObjectivesTo determine the diagnostic accuracy of combined 320-detector row computed tomography coronary angiography (CTA) and adenosine stress CT myocardial perfusion imaging (CTP) in detecting perfusion abnormalities caused by obstructive coronary artery disease (CAD).MethodsTwenty patients with suspected CAD who underwent initial investigation with single-photon-emission computed tomography myocardial perfusion imaging (SPECT-MPI) were recruited and underwent prospectively-gated 320-detector CTA/CTP and invasive angiography. Two blinded cardiologists evaluated invasive angiography images quantitatively (QCA). A blinded nuclear physician analysed SPECT-MPI images for fixed and reversible perfusion defects. Two blinded cardiologists assessed CTA/CTP studies qualitatively. Vessels/territories with both >50xa0% stenosis on QCA and corresponding perfusion defect on SPECT-MPI were defined as ischaemic and formed the reference standard.ResultsAll patients completed the CTA/CTP protocol with diagnostic image quality. Of 60 vessels/territories, 17 (28xa0%) were ischaemic according to QCA/SPECT-MPI criteria. Sensitivity, specificity, PPV, NPV and area under the ROC curve for CTA/CTP was 94xa0%, 98xa0%, 94xa0%, 98xa0% and 0.96 (Pu2009<u20090.001) on a per-vessel/territory basis. Mean CTA/CTP radiation dose was 9.2u2009±u20097.4xa0mSv compared with 13.2u2009±u20092.2xa0mSv for SPECT-MPI (Pu2009<u20090.001).ConclusionsCombined 320-detector CTA/CTP is accurate in identifying obstructive CAD causing perfusion abnormalities compared with combined QCA/SPECT-MPI, achieved with lower radiation dose than SPECT-MPI.Key Points• Advances in CT technology provides comprehensive anatomical and functional cardiac information.n • Combined 320-detector CTA/adenosine-stress CTP is feasible with excellent image quality.n • Combined CTA/CTP is accurate in identifying myocardial ischaemia compared with QCA/SPECT-MPI.n • Combined CTA/CTP results in lower patient radiation exposure than SPECT-MPI.n • CTA/CTP may become an established imaging technique for suspected CAD.

320-row CT coronary angiography predicts freedom from revascularisation and acts as a gatekeeper to defer invasive angiography in stable coronary artery disease: a fractional flow reserve-correlated study

AbstractObjectivesTo determine the accuracy of 320-row multidetector coronary computed tomography angiography (M320-CCTA) to detect functional stenoses using fractional flow reserve (FFR) as the reference standard and to predict revascularisation in stable coronary artery disease.MethodsOne hundred and fifteen patients (230 vessels) underwent M320-CCTA and FFR assessment and were followed for 18xa0months. Diameter stenosis on invasive angiography (ICA) and M320-CCTA were assessed by consensus by two observers and significant stenosis was defined as ≥50xa0%. FFR ≤0.8 indicated functionally significant stenoses.ResultsM320-CCTA had 94xa0% sensitivity and 94xa0% negative predictive value (NPV) for FFR ≤0.8. Overall accuracy was 70xa0%, specificity 54xa0% and positive predictive value 65xa0%. On receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) for CCTA to predict FFR ≤0.8 was 0.74 which was comparable with ICA. The absence of a significant stenosis on M320-CCTA was associated with a 6xa0% revascularisation rate. M320-CCTA predicted revascularisation with an AUC of 0.71 which was comparable with ICA.ConclusionsM320-CCTA has excellent sensitivity and NPV for functional stenoses and therefore may act as an effective gatekeeper to defer ICA and revascularisation. Like ICA, M320-CCTA lacks specificity for functional stenoses and only has moderate accuracy to predict the need for revascularisation.Key Points• Important information about the heart is provided by 320-row multidetector CT coronary angiography (M320-CCTA).n • M320-CCTA accurately detects and excludes functional stenoses determined by fractional flow reserve (FFR).n • Non-significant stenoses on M320-CCTA associated with fewer cardiac events and less revascularisation.n • M320-CCTA may act as a gatekeeper for invasive angiography and inappropriate revascularisation.n • Like ICA, M320-CCTA only has moderate accuracy to predict vessels requiring revascularisation.

Magnetic resonance-derived circumferential strain provides a superior and incremental assessment of improvement in contractile function in patients early after ST-segment elevation myocardial infarction

AbstractBackgroundWe evaluate whether circumferential strain derived from grid-tagged CMR is a better method for assessing improvement in segmental contractile function after STEMI compared to late gadolinium enhancement (LGE).MethodsSTEMI patients post primary PCI underwent baseline CMR (day 3) and follow-up (day 90). Cine, grid-tagged and LGE images were acquired. Baseline LGE infarct hyperenhancement was categorised as ≤25xa0%, 26-50xa0%, 51-75xa0% and >75xa0% hyperenhancement. The segmental baseline circumferential strain (CS) and circumferential strain rate (CSR) were calculated from grid-tagged images. Segments demonstrating an improvement in wall motion of ≥1 grade compared to baseline were regarded as having improved segmental contractile-function.ResultsForty-five patients (aged 58u2009±u200912xa0years) and 179 infarct segments were analysed. A baseline CS cutoff of -5xa0% had sensitivity of 89xa0% and specificity of 70xa0% for detection of improvement in segmental-contractile-function. On receiver-operating characteristic analysis for predicting improvement in contractile function, AUC for baseline CS (0.82) compared favourably to LGE hyperenhancement (0.68), MVO (0.67) and baseline-CSR (0.74). On comparison of AUCs, baseline CS was superior to LGE hyperenhancement and MVO in predicting improvement in contractile function (Pu2009<u20090.001). On multivariate-analysis, baseline CS was the independent predictor of improvement in segmental contractile function (Pu2009<u20090.001).ConclusionGrid-tagged CMR-derived baseline CS is a superior predictor of improvement in segmental contractile function, providing incremental value when added to LGE hyperenhancement and MVO following STEMI.Key points• Baseline CS predicts contractile function recovery better than LGE and MVO following STEMIn • Baseline CS predicts contractile function recovery better than baseline CSR following STEMIn • Baseline CS provides incremental value to LGE and MVO following STEMI

Percutaneous Coronary Intervention Enhances Accelerative Wave Intensity in Coronary Arteries

Background The systolic forward travelling compression wave (sFCW) and diastolic backward travelling decompression waves (dBEW) predominantly accelerate coronary blood flow. The effect of a coronary stenosis on the intensity of these waves in the distal vessel is unknown. We investigated the relationship between established physiological indices of hyperemic coronary flow and the intensity of the two major accelerative coronary waves identified by Coronary Wave Intensity analysis (CWIA). Methodology / Principal Findings Simultaneous intracoronary pressure and velocity measurement was performed during adenosine induced hyperemia in 17 patients with pressure / Doppler flow wires positioned distal to the target lesion. CWI profiles were generated from this data. Fractional Flow Reserve (FFR) and Coronary Flow Velocity Reserve (CFVR) were calculated concurrently. The intensity of the dBEW was significantly correlated with FFR (R = -0.70, P = 0.003) and CFVR (R = -0.73, P = 0.001). The intensity of the sFCW was also significantly correlated with baseline FFR (R = 0.71, p = 0.002) and CFVR (R = 0.59, P = 0.01). Stenting of the target lesion resulted in a median 178% (interquartile range 55–280%) (P<0.0001) increase in sFCW intensity and a median 117% (interquartile range 27–509%) (P = 0.001) increase in dBEW intensity. The increase in accelerative wave intensity following PCI was proportionate to the baseline FFR and CFVR, such that stenting of lesions associated with the greatest flow limitation (lowest FFR and CFVR) resulted in the largest increases in wave intensity. Conclusions Increasing ischemia severity is associated with proportionate reductions in cumulative intensity of both major accelerative coronary waves. Impaired diastolic microvascular decompression may represent a novel, important pathophysiologic mechanism driving the reduction in coronary blood flow in the setting of an epicardial stenosis.