Nina Ajmone Marsan

Assessment of left ventricular dyssynchrony by speckle tracking strain imaging comparison between longitudinal, circumferential, and radial strain in cardiac resynchronization therapy.

OBJECTIVES The objective of this study was to assess the usefulness of each type of strain for left ventricular (LV) dyssynchrony assessment and its predictive value for a positive response after cardiac resynchronization therapy (CRT). Furthermore, changes in extent of LV dyssynchrony for each type of strain were evaluated during follow-up. BACKGROUND Different echocardiographic techniques have been proposed for assessment of LV dyssynchrony. The novel 2-dimensional (2D) speckle tracking strain analysis technique can provide information on radial strain (RS), circumferential strain (CS), and longitudinal strain (LS). METHODS In 161 patients, 2D echocardiography was performed at baseline and after 6 months of CRT. Extent of LV dyssynchrony was calculated for each type of strain. Response to CRT was defined as a decrease in LV end-systolic volume >/=15% at follow-up. RESULTS At follow-up, 88 patients (55%) were classified as responders. Differences in baseline LV dyssynchrony between responders and nonresponders were noted only for RS (251 +/- 138 ms vs. 94 +/- 65 ms; p < 0.001), whereas no differences were noted for CS and LS. A cut-off value of radial dyssynchrony >/=130 ms was able to predict response to CRT with a sensitivity of 83% and a specificity of 80%. In addition, a significant decrease in extent of LV dyssynchrony measured with RS (from 251 +/- 138 ms to 98 +/- 92 ms; p < 0.001) was demonstrated only in responders. CONCLUSIONS Speckle tracking radial strain analysis constitutes the best method to identify potential responders to CRT. Reduction in LV dyssynchrony after CRT was only noted in responders.

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.

Relative Merits of Left Ventricular Dyssynchrony, Left Ventricular Lead Position, and Myocardial Scar to Predict Long-Term Survival of Ischemic Heart Failure Patients Undergoing Cardiac Resynchronization Therapy

Background— The relative merits of left ventricular (LV) dyssynchrony, LV lead position, and myocardial scar to predict long-term outcome after cardiac resynchronization therapy remain unknown and were evaluated in the present study. Methods and Results— In 397 ischemic heart failure patients, 2-dimensional speckle tracking imaging was performed, with comprehensive assessment of LV radial dyssynchrony, identification of the segment with latest mechanical activation, and detection of myocardial scar in the segment where the LV lead was positioned. For LV dyssynchrony, a cutoff value of 130 milliseconds was used. Segments with <16.5% radial strain in the region of the LV pacing lead were considered to have extensive myocardial scar (>50% transmurality, validated in a subgroup with contrast-enhanced magnetic resonance imaging). The LV lead position was derived from chest x-ray. Long-term follow-up included all-cause mortality and hospitalizations for heart failure. Mean baseline LV radial dyssynchrony was 133±98 milliseconds. In 271 patients (68%), the LV lead was placed at the latest activated segment (concordant LV lead position), and the mean value of peak radial strain at the targeted segment was 18.9±12.6%. Larger LV radial dyssynchrony at baseline was an independent predictor of superior long-term survival (hazard ratio, 0.995; P=0.001), whereas a discordant LV lead position (hazard ratio, 2.086; P=0.001) and myocardial scar in the segment targeted by the LV lead (hazard ratio, 2.913; P<0.001) were independent predictors of worse outcome. Addition of these 3 parameters yielded incremental prognostic value over the combination of clinical parameters. Conclusions— Baseline LV radial dyssynchrony, discordant LV lead position, and myocardial scar in the region of the LV pacing lead were independent determinants of long-term prognosis in ischemic heart failure patients treated with cardiac resynchronization therapy. Larger baseline LV dyssynchrony predicted superior long-term survival, whereas discordant LV lead position and myocardial scar predicted worse outcome.

Strain analysis in patients with severe aortic stenosis and preserved left ventricular ejection fraction undergoing surgical valve replacement

AIMS To evaluate myocardial multidirectional strain and strain rate (S-and-SR) in severe aortic stenosis (AS) patients with preserved left ventricular (LV) ejection fraction (EF), using two-dimensional speckle-tracking strain imaging (2D-STI). The long-term effect of aortic valve replacement (AVR) on S-and-SR was also evaluated. METHODS AND RESULTS Changes in LV radial, circumferential, and longitudinal S-and-SR were evaluated in 73 severe AS patients (65 +/- 13 years; aortic valve area 0.8 +/- 0.2 cm2) with preserved LVEF (61 +/- 11%), before and 17 months after AVR. Strain and strain rate data were compared with data from 40 controls (20 healthy individuals and 20 patients with LV hypertrophy) matched by age, gender, body surface area, and LVEF. Compared with controls, severe AS patients had significantly decreased values of LV S-and-SR in the radial (33.1 +/- 14.8%, P = 0.2; 1.7 +/- 0.5 s(-1), P = 0.003), circumferential (-15.2 +/- 5.0%, P = 0.001; -0.9 +/- 0.3 s(-1), P < 0.0001), and longitudinal (-14.6 +/- 4.1%, P < 0.0001; -0.8 +/- 0.2 s(-1), P < 0.0001) directions. At 17 months after AVR, LV S-and-SR significantly improved in all the three directions, whereas LVEF remained unchanged (60 +/- 12%, P = 0.7). CONCLUSION In severe AS patients, impaired LV S-and-SR existed although LVEF was preserved. After AVR, a significant S-and-SR improvement in all the three directions was observed. These subtle changes in LV contractility can be detected by 2D-STI.

Prognostic value of right ventricular longitudinal peak systolic strain in patients with pulmonary hypertension.

Background—Right ventricular (RV) function is an important prognostic marker in patients with pulmonary hypertension. The present evaluation assessed the prognostic value of RV longitudinal peak systolic strain (LPSS) in patients with pulmonary hypertension. Methods and Results—A total of 150 patients with pulmonary hypertension of different etiologies (mean age, 59±15 years; 37.3% male) were evaluated. RV fractional area change and tricuspid annular plane systolic excursion index were evaluated with 2-dimensional echocardiography. RV LPSS was assessed with speckle-tracking echocardiography. The patient population was categorized according to a RV LPSS value of –19%. Among several clinical and echocardiographic parameters, the significant determinants of all-cause mortality were evaluated. There were no significant differences in age, sex, pulmonary hypertension cause and left ventricular ejection fraction between patients with RV LPSS <−19% and patients with RV LPSS ≥−19%. However, patients with RV LPSS ≥−19% had significantly worse New York Heart Association functional class (2.7±0.6 versus 2.3±0.8; P=0.003) and lower tricuspid annular plane systolic excursion (16±4 mm versus 18±3 mm; P<0.001) than their counterparts. During a median follow-up of 2.6 years, 37 patients died. RV LPSS was a significant determinant of all-cause mortality (HR, 3.40; 95% CI, 1.19–9.72; P=0.02). Conclusions—In patients with pulmonary hypertension, RV LPSS is significantly associated with all-cause mortality. RV LPSS may be a valuable parameter for risk stratification of these patients. Future studies are needed to confirm these results in the pulmonary hypertension subgroups.

Reference Values for Right Ventricular Volumes and Ejection Fraction With Real-Time Three-Dimensional Echocardiography: Evaluation in a Large Series of Normal Subjects

BACKGROUND The quantification of right ventricular (RV) size and function is of diagnostic and prognostic importance. Recently, new software for the analysis of RV geometry using three-dimensional (3D) echocardiographic images has been validated. The aim of this study was to provide normal reference values for RV volumes and function using this technique. METHODS A total of 245 subjects, including 15 to 20 subjects for each gender and age decile, were studied. Dedicated 3D acquisitions of the right ventricle were obtained in all subjects. RESULTS The mean RV end-diastolic and end-systolic volumes were 49 +/- 10 and 16 +/- 6 mL/m2 respectively, and the mean RV ejection fraction was 67 +/- 8%. Significant correlations were observed between RV parameters and body surface area. Normalized RV volumes were significantly correlated with age and gender. RV ejection fractions were lower in men, but differences across age deciles were not evident. CONCLUSION The current study provides normal reference values for RV volumes and function that may be useful for the identification of clinical abnormalities.

Impact of left ventricular systolic function on clinical and echocardiographic outcomes following transcatheter aortic valve implantation for severe aortic stenosis

BACKGROUND This study aimed to evaluate the impact of baseline left ventricular (LV) systolic function on clinical and echocardiographic outcomes following transcatheter aortic valve implantation (TAVI). Survival of patients undergoing TAVI was also compared with that of a population undergoing surgical aortic valve replacement. METHODS One hundred forty-seven consecutive patients (mean age=80±7 years) undergoing TAVI in 2 centers were included. Mean follow-up period was 9.1±5.1 months. RESULTS At baseline, 34% of patients had impaired LV ejection fraction (LVEF) (<50%) and 66% had normal LVEF (≥50%). Procedural success was similar in these 2 groups (94% vs 97%, P=.41). All patients achieved improvement in transvalvular hemodynamics. At follow-up, patients with a baseline LVEF<50% showed marked LV reverse remodeling, with improvement of LVEF (from 37%±8% to 51%±11%). Early and late mortality rates were not different between the 2 groups, despite a higher rate of combined major adverse cardiovascular events (MACEs) in patients with a baseline LVEF<50%. The predictors of cumulative MACEs were baseline LVEF (HR=0.97, 95% CI=0.94-0.99) and preoperative frailty (HR=4.20, 95% CI=2.00-8.84). In addition, long-term survival of patients with impaired or normal LVEF was comparable with that of a matched population who underwent surgical aortic valve replacement. CONCLUSIONS TAVI resulted in significant improvement in LV function and survival benefit in high-risk patients with severe aortic stenosis, regardless of baseline LVEF. Patients with a baseline LVEF<50% were at higher risk of combined MACEs.

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.

Mitral valve and tricuspid valve blood flow: Accurate quantification with 3D velocity-encoded MR imaging with retrospective valve tracking

PURPOSE To validate flow assessment performed with three-dimensional (3D) three-directional velocity-encoded (VE) magnetic resonance (MR) imaging with retrospective valve tracking and to compare this modality with conventional two-dimensional (2D) one-directional VE MR imaging in healthy subjects and patients with regurgitation. MATERIALS AND METHODS Patients and volunteers gave informed consent, and local medical ethics committee approval was obtained. Patient data were selected retrospectively and randomly from a database of MR studies obtained between July 2006 and July 2007. The 3D three-directional VE MR images were first validated in vitro and compared with 2D one-directional VE MR images. Mitral valve (MV) and tricuspid valve (TV) flow were assessed in 10 volunteers without valve insufficiency and 20 patients with valve insufficiency, with aortic systolic stroke volume (ASSV) as the reference standard. RESULTS Phantom validation showed less than 5% error for both techniques. In volunteers, 3D three-directional VE MR images showed no bias for MV or TV flow when compared with ASSV, whereas 2D one-directional VE MR images showed significant bias for MV flow (15% overestimation, P < .01). TV flow showed 25% overestimation; however, this was insignificant because of the high standard deviation. Correlation with ASSV was strong for 3D three-directional VE MR imaging (r = 0.96, P < .01 for MV flow; r = 0.88, P < .01 for TV flow) and between MV and TV flow (r = 0.91, P < .01); however, correlation was weaker for 2D one-directional VE MR imaging (r = 0.80, P < .01 for MV flow; r = 0.22, P = .55 for TV flow) and between MV flow and TV flow (r = 0.34, P = .34). In patients (mean regurgitation fractions of 13% and 10% for MV flow and TV flow, respectively), correlation between MV flow and TV flow for 3D three-directional VE MR imaging was strong (r = 0.97, P < .01). CONCLUSION Use of 3D three-directional VE MR imaging enables accurate MV and TV flow quantification, even in patients with valve regurgitation.