Michael Frick

Comparison of Two- and Three-Dimensional Transthoracic Echocardiography to Cardiac Magnetic Resonance Imaging for Assessment of Paravalvular Regurgitation After Transcatheter Aortic Valve Implantation

This study evaluated 2-dimensional (2D) transthoracic echocardiography (TTE) using Valve Academic Research Consortium-2 (VARC-2) criteria and 3-dimensional (3D) TTE for assessment of aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) in comparison with cardiac magnetic resonance (CMR) imaging. In 71 patients, 2D TTE, 3D TTE, and CMR imaging were performed to assess AR severity after TAVI. Using 2D TTE, AR severity was graded according to VARC-2 criteria and regurgitant volume (RVol) was determined. Three-dimensional color Doppler TTE allowed direct planimetry of the vena contracta area of the paravalvular regurgitation jet and calculation of the RVol as product with the velocity-time integral. RVol by CMR imaging was measured by phase-contrast velocity mapping in the ascending aorta. After TAVI, mean RVol determined by CMR imaging was 9.2 ± 9.6 ml/beat and mean regurgitant fraction was 13.3 ± 10.3%. AR was assessed as none or mild in 58 patients (82%) by CMR imaging. Correlation of 3D TTE and CMR imaging on RVol was better than correlation of 2D TTE and CMR imaging (r = 0.895 vs 0.558, p <0.001). There was good agreement between RVol by CMR imaging and by 3D TTE (mean bias = 2.4 ml/beat). Kappa on grading of AR severity was 0.357 between VARC-2 and CMR imaging versus 0.446 between 3D TTE and CMR imaging. Intraobserver variability for analysis of RVol of AR after TAVI was 73.5 ± 52.2% by 2D TTE, 16.7 ± 21.9% by 3D TTE, and 2.2 ± 2.0% by CMR imaging. In conclusion, 2D TTE considering VARC-2 criteria has limitations in the grading of AR severity after TAVI when CMR imaging is used for comparison. Three-dimensional TTE allows quantification of AR with greater accuracy than 2D TTE. Observer variability on RVol after TAVI is considerable using 2D TTE, significantly less using 3D TTE, and very low using CMR imaging.

Multicenter Evaluation of Dynamic Three-Dimensional Magnetic Resonance Myocardial Perfusion Imaging for the Detection of Coronary Artery Disease Defined by Fractional Flow Reserve

Background—First-pass myocardial perfusion cardiovascular magnetic resonance (CMR) imaging yields high diagnostic accuracy for the detection of coronary artery disease (CAD). However, standard 2D multislice CMR perfusion techniques provide only limited cardiac coverage, and hence considerable assumptions are required to assess myocardial ischemic burden. The aim of this prospective study was to assess the diagnostic performance of 3D myocardial perfusion CMR to detect functionally relevant CAD with fractional flow reserve (FFR) as a reference standard in a multicenter setting. Methods and Results—A total of 155 patients with suspected CAD listed for coronary angiography with FFR were prospectively enrolled from 5 European centers. 3D perfusion CMR was acquired on 3T MR systems from a single vendor under adenosine stress and at rest. All CMR perfusion analyses were performed in a central laboratory and blinded to all clinical data. One hundred fifty patients were successfully examined (mean age 62.9±10 years, 45 female). The prevalence of CAD defined by FFR (<0.8) was 56.7% (85 of 150 patients). The sensitivity and specificity of 3D perfusion CMR were 84.7% and 90.8% relative to the FFR reference. Comparison to quantitative coronary angiography (≥50%) yielded a prevalence of 65.3%, sensitivity and specificity of 76.5% and 94.2%, respectively. Conclusions—In this multicenter study, 3D myocardial perfusion CMR proved highly diagnostic for the detection of significant CAD as defined by FFR.

Myocardial Deformation Imaging by Two-Dimensional Speckle-Tracking Echocardiography in Comparison to Late Gadolinium Enhancement Cardiac Magnetic Resonance for Analysis of Myocardial Fibrosis in Severe Aortic Stenosis

Myocardial deformation analysis by speckle-tracking echocardiography (STE) has been used for analysis of myocardial viability and myocardial fibrosis. Patients with severe aortic stenosis are known to develop myocardial fibrosis. This study evaluated the association between myocardial fibrosis determined by late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) and 2-dimensional STE in patients with severe aortic stenosis. In 30 patients (78±7 years) with severe aortic stenosis (mean gradient 53±21 mm Hg), peak systolic circumferential strain based on 2-dimensional echocardiographic parasternal short-axis views and peak systolic longitudinal strain based on apical views were determined for analysis of regional function. LGE CMR was performed to define the amount of fibrosis in each segment within 24 hours of echocardiography. Relative amount of fibrosis was determined based on LGE CMR as gray-scale threshold 6 SDs above the mean signal intensity of the normal remote myocardium. There was a decrease in LGE from base to apex (14.4±8.7% for basal segments, 3.4±3.0% for midventricular segments, and 2.1±3.0% for apical segments; p<0.001). Simultaneously, there was an increase in myocardial deformation expressed as peak systolic longitudinal strain from base to apex (-11.6±7.0% for basal segments, -16.9±6.5% for midventricular segments, and -17.4±7.7% for apical segments; p=0.001). There was a negative correlation between the amount of myocardial fibrosis determined by LGE CMR and peak systolic longitudinal strain for the total left ventricle (r=-0.538, p=0.007). Myocardial fibrosis defined as LGE>10% could be identified by peak systolic longitudinal strain less than -11.6%, with a sensitivity of 65% and a specificity of 75% (area under the receiver operating characteristic curve 0.69). In conclusion, myocardial fibrosis increases from apical to basal left ventricular segments in patients with severe aortic stenosis. There is an association between severity of myocardial fibrosis defined by LGE CMR and myocardial deformation by STE.

Regional left ventricular function after transapical vs. transfemoral transcatheter aortic valve implantation analysed by cardiac magnetic resonance feature tracking

AIMS This study analysed the impact of transapical (TA) vs. transfemoral (TF) access site transcatheter aortic valve implantation (TAVI) on post-procedural regional left ventricular (LV) function using cardiac magnetic resonance (CMR) feature tracking (FT). METHODS AND RESULTS CMR was performed 3 months after TAVI on 44 consecutive patients with normal LV ejection fraction prior to TAVI. Twenty patients had TA-TAVI, and 24 had TF-TAVI. Standard cine imaging was performed in three standard cardiac long-axis views (two-, four- and three-chamber views). Myocardial peak systolic radial strain (PSRS) and peak systolic longitudinal strain (PSLS) were analysed based on CMR-FT considering 49 segments in each of the three views. There were no differences in PSRS and PSLS for the basal and mid-ventricular segments between TA- and TF-TAVI groups. In contrast, PSRS and PSLS of apical segments and apical cap were reduced in the TA- compared with the TF-TAVI group (PSRS: 15.7 ± 6.4 vs. 35.9 ± 15.7%, respectively, P < 0.001; PSLS: -8.9 ± 5.3 vs. -16.9 ± 4.3%, respectively, P < 0.001). Comparison of all non-apical segments vs. apical segments and apical cap demonstrated no difference in the TF group (PSRS: 34.6 ± 9.0 vs. 35.9 ± 15.7%; respectively, P = 0.702; PSLS: -17.8 ± 4.6 vs. -16.9 ± 4.3%; respectively, P = 0.802). After TA-TAVI, PSRS and PSLS of the apical segments were reduced compared with the non-apical segments (PSRS: 15.7 ± 6.4 vs. 33.5 ± 7.0%, respectively, P < 0.001; PSLS: -8.9 ± 5.3 vs. -15.5 ± 3.5%, respectively, P < 0.001). CONCLUSION Apical LV function abnormalities can be detected at 3-month follow-up in all TA-TAVI patients using CMR-FT. TA-TAVI results in significant impairment of apical LV function compared with TF-TAVI.

High spatial resolution myocardial perfusion imaging during high dose dobutamine/atropine stress magnetic resonance using k-t SENSE.

PURPOSE To prospectively evaluate the feasibility and diagnostic accuracy of high spatial resolution myocardial perfusion imaging during high dose dobutamine/atropine stress magnetic resonance (DSMR) for the detection of coronary artery disease (CAD). METHODS AND RESULTS DSMR-wall motion was combined with perfusion imaging (DSMR-perfusion) in 78 patients prior to clinically indicated invasive coronary angiography. For DSMR-perfusion an in-plane spatial resolution of 1.5 × 1.5mm(2) was attained by using 8 × k-space and time sensitivity encoding (k-t SENSE). Image quality and extent of artifacts during perfusion imaging were evaluated. Wall motion and perfusion data were interpreted sequentially. Significant CAD (stenosis ≥ 70%) was present in 52 patients and involved 86 coronary territories. One patient did not reach target heart rate despite maximum infusion of dobutamine/atropine. Two studies (3%) were non-diagnostic due k-t SENSE related artifacts resulting from insufficient breathhold capability. Overall image quality was good. Dark-rim artifacts were limited to the endocardial border at a mean width of 1.8mm. The addition of DSMR-perfusion to DSMR-wall motion data improved sensitivity for the detection of CAD (92% vs. 81%, P=0.03) and accurate determination of disease extent (85% vs. 66% of territories, P<0.001). There were no significant differences between DSMR-perfusion and DSRM-wall motion regarding overall specificity (83% vs. 87%, P=1) and accuracy (89% vs. 83%, P=0.13). CONCLUSION High spatial resolution DSMR-perfusion imaging at maximum stress level was feasible, improved sensitivity over DSMR-wall motion for the detection of CAD and allowed an accurate determination of disease extent. Specificity of DSMR-perfusion with k-t SENSE improved compared to prior studies using lower spatial resolution.

Comparison of Accuracy of Mitral Valve Regurgitation Volume Determined by Three-Dimensional Transesophageal Echocardiography Versus Cardiac Magnetic Resonance Imaging

Direct planimetry of anatomic regurgitation orifice area (AROA) using 3-dimensional transesophageal echocardiography (TEE) has been described. This study sought to (1) compare mitral valve regurgitant volume (RV) derived by AROA using 3-dimensional TEE with RV obtained by cardiac magnetic resonance (CMR) imaging and (2) determine the impact of AROA and flow velocity changes throughout systole on the dynamic variation in mitral regurgitation. In 43 patients (71 ± 11 years old) with mild to severe mitral regurgitation, 3-dimensional TEE and CMR were performed. Mitral valve RV was determined based on (1) AROA at 5 subintervals of systole and analysis of the regurgitant continuous-wave Doppler signal at equal durations of systole, (2) effective regurgitation orifice area (EROA) using the proximal isovelocity surface area method, (3) CMR with subtraction of aortic outflow volume from left ventricular stroke volume. RV calculated by AROA tended to overestimate RV less than RV calculated by EROA compared to RV by CMR (average bias +20 ml, 95% confidence interval [CI] -41 to +81, vs +13 ml, 95% CI -22 to 47). In patients with RV >30 ml by CMR, overestimation of RV using the AROA method was less than using the EROA method (difference in means +18 ml, 95% CI 4 to 32, p <0.001). AROA determined by 3-dimensional TEE varied by only 18% among the 5 subintervals of systole, and the velocity time integral of the subinterval with the highest flow was 120% of the subinterval with the lowest flow. In conclusion, 3-dimensional TEE allows accurate analysis of mitral valve RV. In the clinically relevant group of patients with RV >30 ml as defined by CMR, the AROA method results in less overestimation of RV than the EROA method. Changes in AROA during systole contribute much less to dynamic variation in mitral regurgitation severity than changes in regurgitant flow velocity.

Evaluation of aortic regurgitation after transcatheter aortic valve implantation: aortic root angiography in comparison to cardiac magnetic resonance.

AIMS Aortic regurgitation (AR) is common after transcatheter aortic valve implantation (TAVI). Intraprocedural assessment of AR relies on aortic root angiography. Cardiac magnetic resonance (CMR) phase-contrast mapping of the ascending aorta provides accurate AR quantification. This study evaluated the accuracy of AR grading by aortic root angiography after TAVI in comparison to CMR phase-contrast velocity mapping. METHODS AND RESULTS In 69 patients with TAVI for severe aortic stenosis, post-procedural AR was determined by aortic root angiography with visual assessment according to the Sellers classification and by CMR using phase-contrast velocity mapping for analysis of AR volume and fraction. Spearmans correlation coefficient showed a moderate correlation between angiographic analysis of AR grade and CMR-derived AR volume (r=0.41; p<0.01) as well as AR fraction (r=0.42; p<0.01). There was significant overlap between the angiographic Sellers classes compared to CMR-derived AR fractions. Aortic root angiography with cut-off Sellers grade ≥2 had a sensitivity of 71% and a specificity of 98% to detect AR graded as moderate to severe or severe as defined by CMR. CONCLUSIONS There is only a moderate correlation between aortic root angiography and CMR in the classification of AR severity after TAVI. Alternative imaging including multimodality imaging as well as haemodynamic analysis should therefore be considered for intraprocedural AR assessment and guidance of TAVI procedure in cases of uncertainty in AR grading.

Pulmonary perfusion imaging: new insights into functional consequences of pulmonary embolism using a multicomponent cardiovascular magnetic resonance imaging protocol.

To the Editor: Multidetector computed tomography (MDCT) is frequently used as the first-line technique to directly visualize pulmonary embolism (PE) with a reported sensitivity and specificity of 83% to 100% and 89% to 97%, respectively ([1][1]). However, for rapid and profound clinical decision

An undiagnosed double aortic arch hampers a coronary angiography in a patient with LIMA graft.

A 48-year-old male patient with a history of coronary artery bypass surgery by MIDCAB [left internal mammary artery (LIMA) to left anterior descending artery (LAD) due to spontaneous dissection of the proximal vessel) and invasive coronary angiography 12 years ago presented with atypical chest pain. Transthoracic echocardiogram revealed akinesis of the apex, apical anterior wall, mid and apical septum. Subsequently, invasive coronary …

Multicenter evaluation of dynamic three-dimensional whole-heart myocardial perfusion imaging for the detection of coronary artery disease defined by fractional flow reserve

Background Cardiac magnetic resonance (CMR) perfusion imaging yields high diagnostic accuracy for the detection of coronary artery disease (CAD) [1]. However, standard 2D multislice CMR perfusion techniques only provide limited coverage and hence prohibit computation of myocardial ischemic burden. Recently, two single-center 3D CMR perfusion studies have proven highly diagnostic for the detection of CAD relative to quantitative coronary angiography (QCA) [2] and fractional flow reserve (FFR) [3]. The aim of our prospective multicenter study is to assess the diagnostic performance of 3D CMR perfusion imaging in comparison with FFR.