Ludivine Perdrix

Automated left ventricular diastolic function evaluation from phase-contrast cardiovascular magnetic resonance and comparison with Doppler echocardiography

BackgroundEarly detection of diastolic dysfunction is crucial for patients with incipient heart failure. Although this evaluation could be performed from phase-contrast (PC) cardiovascular magnetic resonance (CMR) data, its usefulness in clinical routine is not yet established, mainly because the interpretation of such data remains mostly based on manual post-processing. Accordingly, our goal was to develop a robust process to automatically estimate velocity and flow rate-related diastolic parameters from PC-CMR data and to test the consistency of these parameters against echocardiography as well as their ability to characterize left ventricular (LV) diastolic dysfunction.ResultsWe studied 35 controls and 18 patients with severe aortic valve stenosis and preserved LV ejection fraction who had PC-CMR and Doppler echocardiography exams on the same day. PC-CMR mitral flow and myocardial velocity data were analyzed using custom software for semi-automated extraction of diastolic parameters. Inter-operator reproducibility of flow pattern segmentation and functional parameters was assessed on a sub-group of 30 subjects. The mean percentage of overlap between the transmitral flow segmentations performed by two independent operators was 99.7 ± 1.6%, resulting in a small variability (<1.96 ± 2.95%) in functional parameter measurement. For maximal myocardial longitudinal velocities, the inter-operator variability was 4.25 ± 5.89%. The MR diastolic parameters varied significantly in patients as opposed to controls (p < 0.0002). Both velocity and flow rate diastolic parameters were consistent with echocardiographic values (r > 0.71) and receiver operating characteristic (ROC) analysis revealed their ability to separate patients from controls, with sensitivity > 0.80, specificity > 0.80 and accuracy > 0.85. Slight superiority in terms of correlation with echocardiography (r = 0.81) and accuracy to detect LV abnormalities (sensitivity > 0.83, specificity > 0.91 and accuracy > 0.89) was found for the PC-CMR flow-rate related parameters.ConclusionsA fast and reproducible technique for flow and myocardial PC-CMR data analysis was successfully used on controls and patients to extract consistent velocity-related diastolic parameters, as well as flow rate-related parameters. This technique provides a valuable addition to established CMR tools in the evaluation and the management of patients with diastolic dysfunction.

Evaluation of aortic valve stenosis using cardiovascular magnetic resonance: comparison of an original semiautomated analysis of phase-contrast cardiovascular magnetic resonance with Doppler echocardiography.

Background—Accurate quantification of aortic valve stenosis (AVS) is needed for relevant management decisions. However, transthoracic Doppler echocardiography (TTE) remains inconclusive in a significant number of patients. Previous studies demonstrated the usefulness of phase-contrast cardiovascular magnetic resonance (PC-CMR) in noninvasive AVS evaluation. We hypothesized that semiautomated analysis of aortic hemodynamics from PC-CMR might provide reproducible and accurate evaluation of aortic valve area (AVA), aortic velocities, and gradients in agreement with TTE. Methods and Results—We studied 53 AVS patients (AVATTE=0.87±0.44 cm2) and 21 controls (AVATTE=2.96±0.59 cm2) who had TTE and PC-CMR of aortic valve and left ventricular outflow tract on the same day. PC-CMR data analysis included left ventricular outflow tract and aortic valve segmentation, and extraction of velocities, gradients, and flow rates. Three AVA measures were performed: AVACMR1 based on Hakki formula, AVACMR2 based on continuity equation, AVACMR3 simplified continuity equation=left ventricular outflow tract peak flow rate/aortic peak velocity. Our analysis was reproducible, as reflected by low interoperator variability (<4.56±4.40%). Comparison of PC-CMR and TTE aortic peak velocities and mean gradients resulted in good agreement (r=0.92 with mean bias=−29±62 cm/s and r=0.86 with mean bias=−12±15 mm Hg, respectively). Although good agreement was found between TTE and continuity equation–based CMR-AVA (r>0.94 and mean bias=−0.01±0.38 cm2 for AVACMR2, −0.09±0.28 cm2 for AVACMR3), AVACMR1 values were lower than AVATTE especially for higher AVA (mean bias=−0.45±0.52 cm2). Besides, ability of PC-CMR to detect severe AVS, defined by TTE, provided the best results for continuity equation–based methods (accuracy >94%). Conclusions—Our PC-CMR semiautomated AVS evaluation provided reproducible measurements that accurately detected severe AVS and were in good agreement with TTE.

Evaluation of Aortic Valve Stenosis using Cardiovascular Magnetic Resonance: Comparison of an Original Semi-Automated Analysis of Phase-Contrast-CMR with Doppler Echocardiography

Background—Accurate quantification of aortic valve stenosis (AVS) is needed for relevant management decisions. However, transthoracic Doppler echocardiography (TTE) remains inconclusive in a significant number of patients. Previous studies demonstrated the usefulness of phase-contrast cardiovascular magnetic resonance (PC-CMR) in noninvasive AVS evaluation. We hypothesized that semiautomated analysis of aortic hemodynamics from PC-CMR might provide reproducible and accurate evaluation of aortic valve area (AVA), aortic velocities, and gradients in agreement with TTE. Methods and Results—We studied 53 AVS patients (AVATTE=0.87±0.44 cm2) and 21 controls (AVATTE=2.96±0.59 cm2) who had TTE and PC-CMR of aortic valve and left ventricular outflow tract on the same day. PC-CMR data analysis included left ventricular outflow tract and aortic valve segmentation, and extraction of velocities, gradients, and flow rates. Three AVA measures were performed: AVACMR1 based on Hakki formula, AVACMR2 based on continuity equation, AVACMR3 simplified continuity equation=left ventricular outflow tract peak flow rate/aortic peak velocity. Our analysis was reproducible, as reflected by low interoperator variability (<4.56±4.40%). Comparison of PC-CMR and TTE aortic peak velocities and mean gradients resulted in good agreement (r=0.92 with mean bias=−29±62 cm/s and r=0.86 with mean bias=−12±15 mm Hg, respectively). Although good agreement was found between TTE and continuity equation–based CMR-AVA (r>0.94 and mean bias=−0.01±0.38 cm2 for AVACMR2, −0.09±0.28 cm2 for AVACMR3), AVACMR1 values were lower than AVATTE especially for higher AVA (mean bias=−0.45±0.52 cm2). Besides, ability of PC-CMR to detect severe AVS, defined by TTE, provided the best results for continuity equation–based methods (accuracy >94%). Conclusions—Our PC-CMR semiautomated AVS evaluation provided reproducible measurements that accurately detected severe AVS and were in good agreement with TTE.

How to calculate left ventricular mass in routine practice? An echocardiographic versus cardiac magnetic resonance study

BACKGROUND An accurate assessment of left ventricular (LV) mass is important for the detection of LV hypertrophy. AIMS To assess the accuracy of four echocardiographic imaging modalities for assessing LV mass compared with cardiac magnetic resonance (CMR). METHODS We prospectively studied 40 consecutive patients, who underwent an echocardiographic examination using four imaging modalities (M-mode fundamental imaging [FI], M-mode harmonic imaging [HI], two-dimensional [2D] FI and 2D HI) and CMR (our gold standard for LV mass measurement). All echocardiographic measurements were performed by two independent observers. RESULTS All echocardiographic modes significantly overestimated LV mass compared with CMR (P≤0.04), except 2D FI (P=0.25). This overestimation was significantly higher with HI (up to 15.5%) compared with FI (up to 5.7%; P≤0.04). Significant correlations were observed between the different echocardiographic methods and the two observers. The interobserver agreement over LV mass measurement was lower with FI (intraclass coefficient [ICC] range, 0.66-0.73) than with HI (ICC range, 0.72-0.82), and the best agreement was obtained with 2D HI (ICC, 0.82). Good agreement between CMR and all echocardiographic methods was observed among the smallest LV diameters (ICC range, 0.62-0.85), but not among the largest LV diameters (ICC range, 0-0.22). CONCLUSIONS HI overestimates LV mass compared with FI and CMR; this leads to overestimation of prevalence of LV hypertrophy in a population of hypertensive patients. HI improves interobserver reproducibility of LV mass measurement compared with FI, leading to a significant decrease in the number of patients required for clinical trials evaluating LV mass regression. Accuracy of LV mass measurement by echocardiography is affected by LV geometry.

Left atrial aging: a cardiac magnetic resonance feature-tracking study.

Importance of left atrial (LA) phasic function evaluation is increasingly recognized for its incremental value in terms of prognosis and risk stratification. LA phasic deformation in the pathway of normal aging has been characterized using echocardiographic speckle tracking. However, no data are available regarding age-related variations using feature-racking (FT) techniques from standard cine magnetic resonance imaging (MRI). We studied 94 healthy adults (41 ± 14 yr, 47 women), who underwent MRI and Doppler echocardiography on the same day for left ventricular (LV) diastolic function evaluation. From cine MRI, longitudinal strain and strain rate, radial motion fraction, and radial relative velocity, respectively, corresponding to the reservoir, conduit, and LA contraction phases, were measured using dedicated FT software. Longitudinal strain and radial motion fraction decreased gradually and significantly with aging for both reservoir (r > 0.31, P < 0.003) and conduit (r > 0.54, P < 0.001) phases, whereas they remained unchanged during the LA contraction phase. Subsequently, the LA contraction-to-reservoir ratio increased significantly with age (r > 0.44, P < 0.001). Longitudinal strain rate and radial relative velocity significantly decreased with age (reservoir: r = 0.39, P < 0.001, conduit: r > 0.54, P < 0.001), and these associations tended to be stronger in women than in men. Finally, associations of LA functional indexes with age were stronger in individuals with lower transmitral early-to-atrial maximal velocity ratio and mitral annulus maximal longitudinal velocity, as well as higher transmitral early maximal-to-mitral annulus maximal longitudinal velocity ratio, highlighting the LV-LA interplay. Age-related changes in LA phasic function indexes were quantified by cine MRI images using a FT technique and were significantly related to age and LV diastolic function.

Greater efficacy of aldosterone blockade and diuretic reinforcement vs. dual renin-angiotensin blockade for left ventricular mass regression in patients with resistant hypertension.

Objectives: We report the results of an echocardiographic substudy carried out in a trial comparing the effects of two different treatment strategies – mineralocorticoid receptor blockade (MRB) and dual renin–angiotensin system blockade (RASB) – in patients with resistant hypertension. Both strategies reduce left ventricular mass index (LVMI), but they have not been compared in patients with resistant hypertension. Methods: After 4-week treatment with 300 mg irbesartan + 12.5 mg hydrochorothiazide + 5 mg amlodipine, 86 patients with resistant hypertension were randomized to the add-on 25 mg spironolactone (MRB group, n = 46) or 5 mg ramipril (RASB group, n = 40) groups for 12 weeks. Treatment intensity was increased at week 4, 8 or 10 if home blood pressure (BP) was equal to or above 135/85 mmHg, by sequentially adding 20–40 mg furosemide and 5 mg amiloride (MRB group), or 10 mg ramipril and 5–10 mg bisoprolol (RASB group). Transthoracic echography was performed at baseline and week 12. Results: Daytime ambulatory BP decreased by 19 ± 12/11 ± 8 mmHg in the MRB group and by 8 ± 13/7 ± 7 mmHg in the RASB group (P = 0.0003/0.03). LVMI decreased by 8.2 ± 18.9 g/m2 in the MRB group, whereas it increased by 1.8 ± 19.1 g/m2 in the RASB group (P = 0.03). The decreases in posterior wall thickness, left ventricular (LV) end-systolic diameter, E/e′ ratio and left atrial area were significantly greater with MRB than with RASB. The difference between groups remained significant after adjustment for the decrease in ambulatory BP. Conclusion: In patients with resistant hypertension, MRB-based treatment decreased both BP and LVMI more efficiently than a strategy based on dual RASB.

Cryoglobulin-Induced Cardiomyopathy

From the Departments of*Nephrology, †CardiovascularImaging, and ‡Cardiology,Hopital Europeen GeorgesPompidou, AssistancePublique Hopitaux de Paris,and the §Institut Nationalde la Sante et de laRecherche Medicale UMR678, Universite Paris-Descartes, Paris, France.Manuscript receivedSeptember 22, 2009;accepted September 30, 2009.

Associations between native myocardial T1 and diastolic function evaluated by PC-CMR in patients with severe aortic valve stenosis

Background To assess the relationship between the presence of myocardial interstitial fibrosis as reflected by the increase in native T1 values and alterations in left ventricular (LV) diastolic function evaluated by phase contrast cardiac magnetic resonance (PC-CMR), in subjects with severe aortic valve stenosis (AVS). Methods We studied 20 subjects (71±10 years) with severe AVS including 19 with a preserved ejection fraction. All patients underwent transthoracic echocardiogram (TTE) and cardiac magnetic resonance (CMR) exams. CMR included conventional LV systolic function and delayed enhancement evaluations as well as a native T1 mapping acquisition using the modified Look-Locker inversion recovery sequence and velocity encoding data of the transmitral inflow for the evaluation of LV diastolic function. These latter CMR data were analyzed using custom software resulting in segmental T1 values and diastolic parameters such as transmitral peak velocities (E, A), peak flow rates (Ef, Af), filling volume (FV), and myocardial peak velocities. Results For all patients, TTE revealed the presence of severe AVS according to ESC criteria (aortic valve area indexed to BSA= 0.43±0.09 cm2/m2 and mean gradient 54 ±14mmHg). When compared to CMR data of 34 elderly controls (60±8 years) despite the preserved ejection fraction (patients=66±10%; controls=66±4%), diastolic parameters indicated an impaired LV relaxation in patients with severe AVS. Importantly, while dense fibrosis volume quantified from delayed enhancement images was not related to diastolic function parameters, a significant relation was found between native myocardial T1 values and parameters of LV filling such as: the ratio between the peak filling rate and the peak atrial rate EfMR/AfMR (r=0.51; p<0.05); the ratio between the peak atrial rate and the filling volume Af/FVMR (r=0.67; p<0.05); and the peak atrial rate Af (r=0.63; p<0.05). Conclusions Interstitial myocardial fibrosis assessed non-invasively by native T1 is related to the severity of diastolic dysfunction in subjects with severe AVS.

Measuring aortic distensibility with cmr using central pressures estimated in the magnet: comparison with carotid and peripheral pressures

Objective To evaluate the feasibility and consequences on local aortic distensibility estimation of using central pressure measurement in the magnet, simultaneous to aortic imaging with CMR Background Several studies have demonstrated the feasibility and value of studying local aortic strain with CMR. Calculating aortic distensibility ideally requires the knowledge of simultaneously acquired central pressure changes which until recently remained a challenge during CMR. New MR-compatible devices using an oscillometric technique to estimate central pressures from a brachial cuff are now available but poorly evaluated in this setting. Methods We studied 49 subjects (26 men, 23 women, age 44±18 years) free from overt cardiovascular disease. Ascending aortic strain was determined by CMR using an automated segmentation of SSFP cine acquisitions. Central pressures were estimated from 1) carotid pressures measured immediately after the CMR exam using applanation tonometry and 2) brachial cuff pressure measured simultaneously with aortic cine imaging in the magnet, using the Vicorder™ Device . In both cases, mean brachial pressures was integrated in the calculation of central pressures after applying the transfert function. Central pressures were used to calculate the aortic distensibility defined as the ratio between aortic strain and central pulse pressure (AAD-carotid for carotid pressure and AAD-vicorder for the Vicorder device pressure) and applanation tonometry was further used to estimate the carotid augmentation index (AIx) and Carotid-femoral pulse wave velocity (cfPWV). Results Average±SD systolic brachial, carotid and Vicorder pressures were respectively: 114±13, 105±13, 106±14mmHg. We found a strong linear relationship between AADcarotid and AAD-vicorder (b=0.89, R2=0.91, p<0.001) with however a larger spread between values at higher pressures. The mean distensibility difference between the two methods was: -1.1±12 mmHg-1 and variability 0.9%. Expectedly, distensibility values measured using peripheral brachial cuff pressures were lower than using either central pressures due to the amplification phenomenon in relation to vascular aging (Table). The correlations between local aortic distensibility with age, AIx and cfPWV were significantly higher when using AAD-vicorder (respectively: r=-0.82, r=-0.62; r=0.61; p<0.001) than when using AAD-carotid (r=-0.79, r=-0.50, r=-0.58; p<0.001). Conclusions Aortic distensibility may be measured by CMR using central pressures measured directly in the magnet, simultaneously with cine acquisitions. Resulting distensibilities are closely related to those using carotid pressures measured by tonometry outside the magnet and achieve higher correlation with age and markers of global aortic stiffness such as AIx and cfPWV.

Left Ventricle Replacement Fibrosis Detected by CMR Associated With Cardiovascular Events in Systemic Sclerosis Patients

Cardiac involvement is the leading cause of death in systemic sclerosis (SSc), although the condition may remain clinically asymptomatic for a long time [(1)][1]. SSc remains underdiagnosed despite repeated transthoracic echocardiography (TTE). This prospective longitudinal study included all