Jos J.M. Westenberg

Infarct tissue heterogeneity assessed with contrast-enhanced MRI predicts spontaneous ventricular arrhythmia in patients with ischemic cardiomyopathy and implantable cardioverter-defibrillator.

Background—The relation between infarct tissue heterogeneity on contrast-enhanced MRI and the occurrence of spontaneous ventricular arrhythmia (or sudden cardiac death) is unknown. Therefore, the study purpose was to evaluate the predictive value of infarct tissue heterogeneity assessed with contrast-enhanced MRI on the occurrence of spontaneous ventricular arrhythmia with subsequent implantable cardioverter-defibrillator (ICD) therapy (as surrogate of sudden cardiac death) in patients with previous myocardial infarction. Methods and Results—Ninety-one patients (age, 65±11 years) with previous myocardial infarction scheduled for ICD implantation underwent cine MRI to evaluate left ventricular function and volumes and contrast-enhanced MRI for characterization of scar tissue (infarct gray zone as measure of infarct tissue heterogeneity, infarct core, and total infarct size). Appropriate ICD therapy was documented in 18 patients (20%) during a median follow-up of 8.5 months (interquartile range, 2.1 to 20.3). Multivariable Cox proportional hazards analysis revealed that infarct gray zone was the strongest predictor of the occurrence of spontaneous ventricular arrhythmia with subsequent ICD therapy (hazard ratio, 1.49/10 g; CI, 1.01 to 2.20; &khgr;2=4.0; P=0.04). Conclusions—Infarct tissue heterogeneity on contrast-enhanced MRI is the strongest predictor of spontaneous ventricular arrhythmia with subsequent ICD therapy (as surrogate of sudden cardiac death) among other clinical and MRI variables, that is, total infarct size and left ventricular function and volumes, in patients with previous myocardial infarction.

Infarct Tissue Heterogeneity Assessed with Contrast-Enhanced Magnetic Resonance Imaging Predicts Spontaneous Ventricular Arrhythmia in Patients with Ischemic Cardiomyopathy and Implantable Cardioverter-Defibrillator

Background—The relation between infarct tissue heterogeneity on contrast-enhanced MRI and the occurrence of spontaneous ventricular arrhythmia (or sudden cardiac death) is unknown. Therefore, the study purpose was to evaluate the predictive value of infarct tissue heterogeneity assessed with contrast-enhanced MRI on the occurrence of spontaneous ventricular arrhythmia with subsequent implantable cardioverter-defibrillator (ICD) therapy (as surrogate of sudden cardiac death) in patients with previous myocardial infarction. Methods and Results—Ninety-one patients (age, 65±11 years) with previous myocardial infarction scheduled for ICD implantation underwent cine MRI to evaluate left ventricular function and volumes and contrast-enhanced MRI for characterization of scar tissue (infarct gray zone as measure of infarct tissue heterogeneity, infarct core, and total infarct size). Appropriate ICD therapy was documented in 18 patients (20%) during a median follow-up of 8.5 months (interquartile range, 2.1 to 20.3). Multivariable Cox proportional hazards analysis revealed that infarct gray zone was the strongest predictor of the occurrence of spontaneous ventricular arrhythmia with subsequent ICD therapy (hazard ratio, 1.49/10 g; CI, 1.01 to 2.20; &khgr;2=4.0; P=0.04). Conclusions—Infarct tissue heterogeneity on contrast-enhanced MRI is the strongest predictor of spontaneous ventricular arrhythmia with subsequent ICD therapy (as surrogate of sudden cardiac death) among other clinical and MRI variables, that is, total infarct size and left ventricular function and volumes, in patients with previous myocardial infarction.

Reduced aortic elasticity and dilatation are associated with aortic regurgitation and left ventricular hypertrophy in nonstenotic bicuspid aortic valve patients.

OBJECTIVES This study sought to assess elasticity and dimensions of the aorta and their impact on aortic valve competence and left ventricular (LV) function in patients with a nonstenotic bicuspid aortic valve (BAV). BACKGROUND Intrinsic pathology of the aortic wall is a possible explanation for reduced aortic elasticity and aortic dilatation in patients with BAVs, even in the absence of a stenotic aortic valve. The relationship between aortic wall elasticity, aortic dimensions, aortic valve competence, and LV function in patients with BAVs has not previously been studied with magnetic resonance imaging. METHODS Magnetic resonance imaging was performed in 20 patients with nonstenotic BAVs (mean +/- SD, age 27 +/- 11 years) and 20 matched control patients. RESULTS The BAV patients showed reduced aortic elasticity as indicated by increased pulse wave velocity in the aortic arch and descending aorta (5.6 +/- 1.3 m/s vs. 4.5 +/- 1.1 m/s, p = 0.01; and 5.2 +/- 1.8 m/s vs. 4.3 +/- 0.9 m/s, p = 0.03, respectively), and reduced aortic root distensibility (3.1 +/- 1.2 x 10(-3) mm Hg(-1) vs. 5.6 +/- 3.2 x 10(-3) mm Hg(-1), p < 0.01). In addition, BAV patients showed aortic root dilatation as compared with control patients (mean difference 3.6 to 4.2 mm, p < or = 0.04 at all 4 predefined levels). Minor degrees of aortic regurgitation (AR) were present in 11 patients (AR fraction 6 +/- 8% vs. 1 +/- 1%, p < 0.01). The LV ejection fraction was normal (55 +/- 8% vs. 56 +/- 6%, p = 0.61), whereas LV mass was significantly increased in patients (54 +/- 12 g/m2 vs. 46 +/- 12 g/m2, p = 0.04). Dilatation at the level of the aortic annulus (r = 0.45, p = 0.044) and reduced aortic root distensibility (r = 0.37, p = 0.041) correlated with AR fraction. Increased pulse wave velocity in the aortic arch correlated with increased LV mass (r = 0.42, p = 0.041). CONCLUSIONS Reduced aortic elasticity and aortic root dilatation were frequently present in patients with nonstenotic BAVs. In addition, reduced aortic wall elasticity was associated with severity of AR and LV hypertrophy.

Magnetic resonance imaging and response to cardiac resynchronization therapy: relative merits of left ventricular dyssynchrony and scar tissue

AIM To assess the relative value of a novel measure of left ventricular (LV) dyssynchrony derived from magnetic resonance imaging (MRI) and the extent of scar tissue for prediction of response to cardiac resynchronization therapy (CRT). METHODS AND RESULTS Thirty-five heart failure patients scheduled for CRT were included. Left ventricular dyssynchrony was defined as the standard deviation of 16 segment time-to-maximum radial wall thickness (SDt-16) obtained from a cine-set of short-axis slices. Delayed-enhanced MRI was performed for scar analysis. Echocardiography was used to determine response to CRT (reduction > or =15% in LV end-systolic volume 6 months after implantation). At follow-up, 21 patients (60%) were classified as responders. On MRI, SDt-16 was significantly higher in responders compared with non-responders (median 97 vs. 60 ms, P < 0.001), whereas the total extent of scar was larger in non-responders (median 35% vs. 3% in responders, P < 0.001). At the logistic regression analysis, SDt-16 was directly associated (OR = 6.3, 95% CI 3.1-9.9, P < 0.001) and the total extent of scar was inversely associated (OR = 0.52, 95% CI 0.43-0.87, P < 0.001) with response to CRT. CONCLUSION Magnetic resonance imaging offers the unique opportunity to assess LV dyssynchrony and scar extent in a single session. Both these parameters are important predictors of echocardiographic response to CRT.

Quantitative assessment of mitral regurgitation: comparison between three-dimensional transesophageal echocardiography and magnetic resonance imaging.

Background— Quantification of mitral regurgitation severity with 2-dimensional (2D) imaging techniques remains challenging. The present study compared the accuracy of 2D transesophageal echocardiography (TEE) and 3-dimensional (3D) TEE for quantification of mitral regurgitation, using MRI as the reference method. Methods and Results— Two-dimensional and 3D TEE and cardiac MRI were performed in 30 patients with mitral regurgitation. Mitral effective regurgitant orifice area (EROA) and regurgitant volume (Rvol) were estimated with 2D and 3D TEE. With 3D TEE, EROA was calculated using planimetry of the color Doppler flow from en face views and Rvol was derived by multiplying the EROA by the velocity time integral of the regurgitant jet. Finally, using MRI, mitral Rvol was quantified by subtracting the aortic flow volume from left ventricular stroke volume. Compared with 3D TEE, 2D TEE underestimated the EROA by a mean of 0.13 cm2. In addition, 2D TEE underestimated the Rvol by 21.6% when compared with 3D TEE and by 21.3% when compared with MRI. In contrast, 3D TEE underestimated the Rvol by only 1.2% when compared with MRI. Finally, one third of the patients in grade 1 and ≥50% of the patients in grade 2 and 3, as assessed with 2D TEE, would have been upgraded to a more severe grade, based on the 3D TEE and MRI measurements. Conclusions— Quantification of mitral EROA and Rvol with 3D TEE is feasible and accurate as compared with MRI and results in less underestimation of the Rvol as compared with 2D TEE.Background—Quantification of mitral regurgitation severity with 2-dimensional (2D) imaging techniques remains challenging. The present study compared the accuracy of 2D transesophageal echocardiography (TEE) and 3-dimensional (3D) TEE for quantification of mitral regurgitation, using MRI as the reference method. Methods and Results—Two-dimensional and 3D TEE and cardiac MRI were performed in 30 patients with mitral regurgitation. Mitral effective regurgitant orifice area (EROA) and regurgitant volume (Rvol) were estimated with 2D and 3D TEE. With 3D TEE, EROA was calculated using planimetry of the color Doppler flow from en face views and Rvol was derived by multiplying the EROA by the velocity time integral of the regurgitant jet. Finally, using MRI, mitral Rvol was quantified by subtracting the aortic flow volume from left ventricular stroke volume. Compared with 3D TEE, 2D TEE underestimated the EROA by a mean of 0.13 cm2. In addition, 2D TEE underestimated the Rvol by 21.6% when compared with 3D TEE and by 21.3% when compared with MRI. In contrast, 3D TEE underestimated the Rvol by only 1.2% when compared with MRI. Finally, one third of the patients in grade 1 and ≥50% of the patients in grade 2 and 3, as assessed with 2D TEE, would have been upgraded to a more severe grade, based on the 3D TEE and MRI measurements. Conclusions—Quantification of mitral EROA and Rvol with 3D TEE is feasible and accurate as compared with MRI and results in less underestimation of the Rvol as compared with 2D TEE.

Noninvasive imaging in cardiac resynchronization therapy--part 1: selection of patients.

Cardiac resynchronization therapy (CRT) is an established therapy for patients with advanced heart failure, depressed left ventricular function, and wide QRS complex. However, individual response varies, and a substantial amount of patients do not respond to CRT. Recent studies observed that assessment of inter‐ and particularly intraventricular dyssynchrony may allow identification of potential responders to CRT. In addition, presence of scar tissue and venous anatomy may play a role in the selection of candidates. In this review, an extensive overview of the available dyssynchrony measurements is provided using echocardiography as well as magnetic resonance imaging (MRI) and nuclear imaging. Furthermore, other information derived from MRI, nuclear imaging, and computed tomography useful for the selection of potential candidates for CRT will be discussed.

Magnetic Resonance Assessment of Aortic Pulse Wave Velocity, Aortic Distensibility, and Cardiac Function in Uncomplicated Type 2 Diabetes Mellitus

BACKGROUND Type 2 diabetes mellitus (DM2) may augment arterial stiffening and thereby modulates left ventricular (LV) function. Cardiovascular magnetic resonance (CMR) is well suited to assess aortic pulse wave velocity (PWV) and aortic distensibility, both markers of arterial stiffness, without the use of geometric assumptions. Furthermore, CMR is a reliable method for assessing left ventricular (LV) function. The purpose of this study was to assess LV function, PWV, and aortic distensibility in patients with DM2 using MR. METHODS Fourteen patients with well controlled, uncomplicated DM2, and 16 age and gender matched healthy subjects were included. PWV was calculated based on MR velocity mapping at two predefined aortic locations. Aortic distensibility was measured in the mid ascending aorta. LV volumes were measured by fast gradient-echo imaging to assess systolic function. Furthermore, mitral inflow was measured by MR velocity mapping to assess diastolic LV function. RESULTS Mean PWV was higher in patients as compared to healthy subjects (6.83 +/- 1.60 m/s vs. 5.65 +/- 0.75 m/s, p < 0.05). This difference was independent of blood pressure. PWV correlated significantly (p < 0.05) with fasting plasma glucose and insulin levels. Aortic distensibility was lower in patients as compared to healthy subjects (4.50 x 10(- 3)+/- 2.24 x 10(- 3) mmHg(- 1) vs. 7.42 x 10(- 3)+/- 3.34 x 10(- 3) mmHg(- 1), p < 0.05). Distensibility correlated negatively with PWV and positively with LV diastolic function (p < 0.05). CONCLUSION A combined CMR assessment of aortic PWV, aortic distensibility, and heart function reveals abnormal PWV and distensibility in patients with DM2, independent of blood pressure. Furthermore, aortic distensibility correlates with diastolic left ventricular function.

Operator Induced Variability in Cardiovascular MR: Left Ventricular Measurements and Their Reproducibility

PURPOSE To assess the intra- and inter-operator variability of the manual planning of cardiovascular magnetic resonance imaging and to evaluate the influence of these factors on the functional parameters of the left ventricle (LV). METHOD The study population consisted of 10 healthy volunteers. For each subject the manual planning of the short-axis cine acquisitions was carried out twice by one operator and once by a second operator. Left ventricular volume, mass, and function were manually evaluated twice by one experienced observer, resulting in an approximation of the intra-observer variability factor. The intra- and inter-operator variation factors were estimated as the difference between the total and intra-observer variation components. RESULTS LV end-diastolic volume varied by 3.3% and 4.16%, and LV end-systolic volume by 5.84% and 6.23% for intra- and inter-operator studies, respectively. The variability for LV mass at end-diastole was equal to 4.23% in both studies. For the ejection fraction the variability was 3.56% and 2.97% for intra- and inter-operator studies, respectively. Comparison of reproducibility between intra- and inter-operator studies resulted in insignificant statistical differences. Bland-Altman limits of agreements revealed no systematic bias in differences between measurements with respect to their means. Reliability of the planning expressed as the angular deviation of the short-axis imaging planes amounts to 2.67 -/+ 1.5 degrees and 4.99 +/- 2.17 degrees for the intra-operator and inter-operator studies, respectively. For EDV, ESV, and EF approximately 75-80% of the total variation can be explained by the within or between operator variation, while the same percentage is 60% for LVM. CONCLUSIONS Our study confirms the excellent inter- and intra-operator reproducibility of the cardiovascular magnetic resonance measurements of the left ventricular volumes and mass in a group of healthy volunteers.

Vessel diameter measurements in gadolinium contrast-enhanced three-dimensional MRA of peripheral arteries

In this study, the possibilities for quantification of vessel diameters of peripheral arteries in gadolinium contrast-enhanced magnetic resonance angiography (Gd CE MRA) were evaluated. Absolute vessel diameter measurements were assessed objectively and semi-automatically in maximum intensity projections (MIPs) of contrast-enhanced T1-weighted 3D spoiled gradient-echo datasets, studied with digital subtraction techniques. In vivo, the complete peripheral arterial bed of six patients was studied, from the aorto-iliac bifurcation down to the distal run-off. By measuring the signal intensity (SI) over the lumen of a vessel in the MIP, an SI-plot was obtained. Next, the vessel boundaries were determined using a threshold algorithm; from these boundary points individual diameter values could be obtained along the trajectory of the vessel. In an in vitro study, an optimal threshold value of 30% of the range of SI-values between the background and the maximal SI in the vessel was obtained for accurate diameter measurement in Gd CE MRA (i.e., full-width 30%-maximum). Furthermore, the relationship between the accuracy of these measurements and the scan resolution was investigated. Accuracy was found to be acceptable (i.e., less than 10% over/underestimation) for vessel sizes covering at least 3 pixels. In six patients, diameters were measured in MIPs of the total datasets (i.e., D(T)) as well as in selective MIPs of the clipped datasets (i.e., D(S)) (n = 209). D(T) and D(S) were statistically significantly correlated (p < 0.01) with a Pearson correlation coefficient rP = 0.98. Measurements in the total MIPs yielded statistically significant (p < 0.01) smaller diameter values compared with measurements in selective MIPs, with a mean difference of 0.15 mm. Diameter values from the selective MIPs of the aorto-iliac arteries were also compared with diameter values measured at corresponding anatomic positions in X-ray angiograms of these patients (i.e., D(x)) (n = 70). D(X) and D(S) were statistically significantly correlated (p < 0.01) with a Pearson correlation coefficient rP = 0.92. Diameters measured in the selective MIPs were smaller than those measured in the X-ray angiograms (mean difference 0.49 mm) and this difference was statistically significant (p < 0.01). In conclusion, diameter values can be evaluated accurately in MIPs of vessels with at least 3 pixels in diameter, using the full-width 30%-maximum criterion.

Association of Aortic Arch Pulse Wave Velocity with Left Ventricular Mass and Lacunar Brain Infarcts in Hypertensive Patients: Assessment with MR Imaging

PURPOSE To assess the possible association between aortic arch stiffness, which may cause hypertensive cardiovascular disease, and cardiac and cerebral end-organ damage in patients with hypertension by using magnetic resonance (MR) imaging. MATERIALS AND METHODS Approval from the local institutional review board was obtained, and patients gave informed consent. Fifty patients with hypertension (31 women and 19 men; mean age +/- standard deviation, 49.2 years +/- 12.7; mean systolic blood pressure, 152.1 mm Hg +/- 22.3; mean diastolic blood pressure, 88.0 mm Hg +/- 13.1), compliant for treatment with antihypertensive medication, were prospectively enrolled for MR examinations of the aorta, heart, and brain with standard pulse sequences. Aortic arch pulse wave velocity (PWV), left ventricular (LV) mass, LV systolic and diastolic function, lacunar brain infarcts, and periventricular and deep white matter hyperintensities (WMHs) were assessed. Univariable and multiple linear and logistic regression analyses were used for statistical analyses. RESULTS Mean aortic arch PWV was 7.3 m/sec +/- 2.5. Aortic arch PWV was statistically significantly associated with LV mass (r = 0.30, P = .03, beta = 1.73); indexes of systolic function, including ejection fraction (r = -0.38, P = .01, beta = -1.12); indexes of diastolic function, including the ratio of early diastolic to atrial contraction peak filling rates (r = -0.44, P < .01, beta = -0.11); lacunar brain infarcts (odds ratio [OR] = 1.8, P < .01); and periventricular (OR = 1.5, P = .01) and deep (OR = 1.6, P = .01) WMHs. Aortic arch PWV was statistically significantly associated with LV mass (r = 0.37, P = .03, beta = 2.11) and lacunar brain infarcts (OR = 1.8, P = .04), independent of age, sex, and hypertension duration, but not with indexes of diastolic and systolic function and WMHs. CONCLUSION Aortic arch stiffness is associated with LV mass and lacunar brain infarcts in hypertensive patients, independent of age, sex, and hypertension duration; these manifestations of end-organ damage may help to risk stratify hypertensive patients.