Trabeculated (Non-Compacted) and Compact Myocardium in Adults: The Multi-Ethnic Study of Atherosclerosis

OBJECTIVES: A high degree of non-compacted (trabeculated) myocardium in relationship to compact myocardium (T/M ratio >2.3) has been associated with a diagnosis of left ventricular non-compaction (LVNC). The purpose of this study was to determine the normal range of the T/M ratio in a large population-based study and to examine the relationship to demographic and clinical parameters.

METHODS: The thickness of trabeculation and the compact myocardium were measured in eight LV regions on long axis cardiac magnetic resonance (CMR) steady-state free precession cine images in 1000 participants (551 women; 68.1±8.9 years) of the Multi-Ethnic Study of Atherosclerosis cohort.

RESULTS: Of 323 participants without cardiac disease or hypertension and with all regions evaluable 140 (43%) had a T/M ratio >2.3 in at least one region; in 20/323 (6%), T/M>2.3 was present in more than two regions. Multivariable linear regression model revealed no association of age, gender, ethnicity, height and weight with maximum T/M ratio in participants without cardiac disease or hypertension (p>0.05). In the entire cohort (n=1000) LVEF (β=-0.02/%; p=0.015), LVEDV (β=0.01/ml; p=<0.0001) and LVESV (β=0.01/ml; p<0.001) were associated with maximum T/M ratio in adjusted models while there was no association with hypertension or myocardial infarction (p>0.05). At the apical level T/M ratios were significantly lower when obtained on short- compared to long-axis images (p=0.017).

CONCLUSIONS: A ratio of trabeculated to compact myocardium of more than 2.3 is common in a large population based cohort. These results suggest reevaluation of the current CMR criteria for LVNC may be necessary.

PMID: 22499849

Quantitative Analysis of Left Ventricular Dyssynchrony using Cardiac Computed Tomography versus Three-Dimensional Echocardiography

OBJECTIVES: We investigated whether cardiac computed tomography (CCT) can determine intraventricular dyssynchrony in comparison to real-time three-dimensional echocardiography (RT3DE) in patients who are considered for cardiac resynchronisation therapy (CRT).

METHODS: 35 patients considered for CRT were examined. Left ventricular (LV) dyssynchrony was quantified by calculating the standard deviation index (SDI) of 17 myocardial LV segments by RT3DE and ECG-gated contrast-enhanced 64-slice dual-source CCT. For both analyses the same software algorithm (4D LV-Analysis) was used.

RESULTS: Close correlations were observed for end-systolic volume, end-diastolic volume and LV ejection fraction between the two techniques (r = 0.94, r = 0.92 and r = 0.95, respectively, P < 0.001 for all). For the global dyssynchrony index SDI, a high correlation was found between RT3DE and CCT (r = 0.84, P < 0.001), which further increased after exclusion of segments with poor image quality by echocardiography (r = 0.90, P < 0.001). The required time for quantitative analysis was significantly shorter (162 ± 22 s vs. 608 ± 112 s per patient, P < 0.001) and reproducibility was significantly higher for CCT compared with RT3DE (interobserver variability of 4.5 ± 3.1% vs. 7.9 ± 6.1%, P < 0.05).

CONCLUSIONS: Quantitative assessment of LV dyssynchrony is feasible by CCT. Owing to its higher reproducibility and faster analysis time compared with RT3DE, this technique may represent a valuable alternative for dyssynchrony assessment. Key Points : • Quantitative assessment of left ventricular dyssynchrony is feasible by cardiac computed tomography (CCT). • This technique has been compared with real-timethree-dimensional echocardiography (RT3DE). • Reproducibility is significantly higher for CCT compared with RT3DE. • Time spent for analysis is significantly shorter for CCT. • Computed tomography may represent a valuable alternative to ultrasound for dyssynchrony assessment.

PMID: 22270144

The Year in Cardiac Imaging

N/A.

PMID:

Performance of 3-Dimensional Echocardiography in Measuring Left Ventricular Volumes and Ejection Fraction: A Systematic Review and Meta-Analysis

OBJECTIVES: The primary aim of this systematic review is to objectively evaluate the test performance characteristics of three-dimensional echocardiography (3DE) in measuring left ventricular (LV) volumes and ejection fraction (EF). Despite its growing use in clinical laboratories, the accuracy of 3DE has not been studied on a large scale. It is unclear if this technology offers an advantage over traditional two-dimensional (2D) methods.

METHODS: We searched for studies that compared LV volumes and EF measured by 3DE and cardiac magnetic resonance (CMR) imaging. A subset of those also compared standard 2D methods with CMR. We used meta-analyses to determine the overall bias and limits of agreement of LV end-diastolic volume (EDV), end-systolic volume (ESV), and EF measured by 3DE and 2D echocardiography (2DE).

RESULTS: Twenty-three studies (1,638 echocardiograms) were included. The pooled biases ± 2 SDs for 3DE were –19.1 ± 34.2 ml, –10.1 ± 29.7 ml, and – 0.6 ± 11.8% for EDV, ESV, and EF, respectively. Nine studies also included data from 2DE, where the pooled biases were –48.2 ± 55.9 ml, –27.7 ± 45.7 ml, and 0.1 ± 13.9% for EDV, ESV, and EF, respectively. In this subset, the difference in bias between 3DE and 2D volumes was statistically significant (p = 0.01 for both EDV and ESV). The difference in variance was statistically significant (p < 0.001) for all 3 measurements.

CONCLUSIONS: Three-dimensional echocardiography underestimates volumes and has wide limits of agreement, but compared with traditional 2D methods in these carefully performed studies, 3DE is more accurate for volumes and more precise in all 3 measurements.

PMID:

Mitral Valve Prolapse With Mid-Late Systolic Mitral Regurgitation: Pitfalls of Evaluation and Clinical Outcome Compared With Holosystolic Regurgitation

OBJECTIVES: Mitral regurgitation (MR) of mitral valve prolapse predominates in late systole but may be holosystolic or purely mid-late systolic, but the impact of MR timing on MR left ventricular and left atrial consequences and outcome is unknown. Whether effective regurgitant orifice (ERO) by the flow convergence method is similarly linked to outcome in mid-late systolic MR and holosystolic MR is uncertain.

METHODS: We comprehensively and prospectively quantified MR in 111 patients with mitral valve prolapse and mid-late systolic MR and matched them to 90 patients with mitral valve prolapse and holosystolic MR for age, gender, atrial fibrillation, ejection fraction, and ERO (flow convergence).

RESULTS: Mid-late systolic MR versus holosystolic MR groups were well matched, including for comorbidity, blood pressure, and heart rate (all P>0.10). Mid-late systolic MR versus holosystolic MR caused similar color jet area, midsystolic regurgitant flow, and peak velocity (P>0.40). Despite identical ERO (0.25±0.15 versus 0.25±0.15 cm(2); P=0.53), the shorter duration of mid-late systolic MR (233±56 versus 426±50 ms; P<0.0001) yielded lower regurgitant volume (24.8±13.4 versus 48.6±25.6 mL; P<0.0001). MR consequences, systolic pulmonary pressure, and left ventricular and left atrial volume index (all P<0.001) were more benign in mid-late systolic MR versus holosystolic MR. Under medical management, fewer cardiac events (5 years: 15.8±4.6% versus 40.4±6.1%; P<0.0001) occurred in mid-late systolic MR versus holosystolic MR, requiring less mitral surgery. Multivariable analysis confirmed the independent association of mid-late systolic MR with benign consequences and outcomes (all P<0.01). Absolute ERO was not linked to outcome, in contrast to regurgitant volume.

CONCLUSIONS: MR of mitral valve prolapse that is purely mid-late systolic causes more benign consequences and outcomes than holosystolic MR. Assessment may be misleading because jet area and ERO by flow convergence appear similar to those of holosystolic MR. However, shorter MR yields lower regurgitant volume, consequences, and benign outcomes. Instantaneous ERO by flow convergence should be interpreted in context, and in mid-late systolic MR, regurgitant volume provides information more reflective of MR severity. Therefore, for clinical management and surgical referral, clinicians should carefully take into account the timing and consequences of MR.

PMID: 22388325

Low Gradient “Severe” Aortic Stenosis with Preserved Left Ventricular Ejection Fraction

In developed nations, aortic stenosis (AS) is the most common valvular heart disease presentation, and its prevalence is increasing due to aging populations.

Accurate diagnosis of the disease process and determination of its severity are essential in clinical decision-making. Although current guidelines recommend measuring transvalvular gradients, maximal velocity, and aortic valve area in determining the disease severity, inconsistent grading of disease severity remains a common problem in clinical practice.

Recent studies suggest that patients with paradoxical low-flow and/or low-gradient, severe AS are at a more advanced stage of the disease process and have a poorer prognosis. This mode of presentation may lead to an undervaluation of symptoms and inappropriate delay of AVR.

Therefore, this challenging clinical situation should be carefully assessed in particular in symptomatic patients and clinical decisions should be tailored individually.

PMID:

Cross-Sectional Computed Tomographic Assessment Improves Accuracy of Aortic Annular Sizing for Transcatheter Aortic Valve Replacement and Reduces the Incidence of Paravalvular Aortic Regurgitation

OBJECTIVES: In an effort to define the gold standard for annular sizing for transcatheter aortic valve replacement (TAVR), we sought to critically analyze and compare the predictive value of multiple measures of the aortic annulus for post-TAVR paravalvular (PV) regurgitation and then assess the impact of a novel cross-sectional computed tomographic (CT) approach toannular sizing. Recent studies have shown clear discrepancies between conventional 2-dimensional (2D) echocardiographic and CT measurements. In terms of aortic annular measurement for TAVR, such findings have lacked the outcome analysis required to inform clinical practice.

METHODS: The discriminatory value of multiple CT annular measures for post-TAVR PV aortic regurgitation was compared with 2D echocardiographic measures. TAVR outcomes with device selection according to aortic annular sizing using a traditional 2D transesophageal echocardiography-guided or a novel CT-guided approach were also studied.

RESULTS: In receiver-operating characteristic models, cross-sectional CT parameters had the highest discriminatory value for post-TAVR PV regurgitation: This was with the area under the curve for [maximal cross-sectional diameter minus prosthesis size] of 0.82 (95% confidence interval: 0.69 to 0.94; p < 0.001) and that for [circumference-derived cross-sectional diameter minus prosthesis size] of 0.81 (95% confidence interval: 0.7 to 0.94; p < 0.001). In contrast, traditional echocardiographic measures were nondiscriminatory in relation to post-TAVR PV aortic regurgitation. The prospective application of a CT-guided annular sizing approach resulted in less PV aortic regurgitation of grade worse than mild after TAVR (7.5% vs. 21.9%; p = 0.045).

CONCLUSIONS: Our data lend strong support to 3-dimensional cross-sectional measures, using CT as the new gold standard foraortic annular evaluation for TAVR with the Edwards SAPIEN device.

PMID: 22365424

3-Dimensional Aortic Annular Assessment by Multidetector Computed Tomography Predicts Moderate or Severe Paravalvular Regurgitation After Transcatheter Aortic Valve Replacement A Multicenter Retrospective Analysis

OBJECTIVES: This study sought to analyze multidetector computed tomography (MDCT) 3-dimensional aortic annular dimensions for the prediction of paravalvular aortic regurgitation (PAR) following transcatheter aortic valve replacement (TAVR). Moderate or severe PAR after TAVR is associated with increased morbidity and mortality.

METHODS: A total of 109 consecutive patients underwent MDCT pre-TAVR with a balloon expandable aortic valve. Differences between transcatheter heart valve (THV) size and MDCT measures of annular size (mean diameter, area, and circumference) were analyzed concerning prediction of PAR. Patients with THV malposition (n = 7) were excluded. In 50 patients, MDCT was repeated after TAVR to assess THV eccentricity (1 – short diameter/long diameter) and expansion (MDCT measured THV area/nominal THV area).

RESULTS: Moderate or severe PAR (13 of 102) was associated with THV undersizing (THV diameter – mean diameter = -0.7 ± 1.4 mm vs. 0.9 ± 1.8 mm for trivial to mild PAR, p < 0.01). The difference between THV size and MDCT annular size was predictive of PAR (mean diameter: area under the curve [AUC]: 0.81, 95% confidence interval [CI]: 0.68 to 0.88; area: AUC: 0.80, 95% CI: 0.65 to 0.90; circumference: AUC: 0.76, 95% CI: 0.59 to 0.91). Annular eccentricity was not associated with PAR (AUC: 0.58, 95% CI: 0.46 to 0.75). We found that 35.3% (36 of 102) and 45.1% (46 of 102) of THVs were undersized relative to the MDCT mean diameter and area, respectively. THV oversizing relative to the annular area was not associated with THV eccentricity or underexpansion (oversized vs. undersized THVs; expansion: 102.7 ± 5.3% vs. 106.1 ± 5.6%, p = 0.03; eccentricity: median: 1.7% [interquartile range: 1.4% to 3.0%] vs. 1.7% [interquartile range: 1.1% to 2.7%], p = 0.28).

CONCLUSIONS: MDCT-derived 3-dimensional aortic annular measurements are predictive of moderate or severe PAR following TAVR. Oversizing of THVs may reduce the risk of moderate or severe PAR.

PMID: 22365423

Intima Media Thickness Variability (IMTV) and its Association With Cerebrovascular Events: A Novel Marker of Carotid Atherosclerosis?

OBJECTIVES: Increased intima-media thickness (IMT) is an early marker of atherosclerotic disease and several prospective studies have demonstrated that IMT is a strong predictor of cerebrovascular complications. In this paper we propose a  novel method to assess IMT, called “intima media thickness variability” (IMTV) and evaluate its relationship with the development of cerebrovascular events.

METHODS: The study was approved by the local IRB. Twenty consecutive patients underwent ultrasound analysis of the carotid arteries (mean age 68 years; age range 59-81 years). The IMT and IMTV of the 40 carotid vessels was assessed. Bland–Altman statistics were employed to measure the inter-observer variability, and ROC analysis was used to assess the association with cerebrovascular events.

RESULTS: In all cases the ROC area under the curve was higher for IMTV than IMT. There was a statistical significant association between IMTV and cerebrovascular events (P=0.018), but no relationship between IMT and events. The results for inter-observer variability showed a systematic error between 0.04 mm and 0.08 mm. In the Person Rho correlation analysis in no case a statistical association between IMT and symptoms was detected whereas in 2 cases (observer 1 and observer 2), a statistically significant association between IMTV and symptoms was found.

CONCLUSIONS: Data of this preliminary study suggest that IMTV may represent a powerful method to assess carotid atherosclerotic disease with a significant association to cerebrovascular events.

PMID:

Impact of Progression of Diastolic Dysfunction on Mortality in Patients With Normal Ejection Fraction

OBJECTIVES: Diastolic dysfunction is an independent predictor of mortality in patients with normal left ventricular ejection fraction. There are limited data, however, on whether worsening of diastolic function is associated with worse prognosis.

METHODS: We reviewed clinical records and echocardiograms of consecutive patients who had baseline echocardiograms between January 1, 2005, and December 31, 2009, that showed left ventricular ejection fraction ≥55% and who subsequently had a follow-up echocardiogram within 6 to 24 months. Diastolic function was labeled as normal, mild, moderate, or severe dysfunction. All-cause mortality was determined by use of the Social Security Death Index. Kaplan-Meier survival analysis and Cox regression analysis with a proportional hazard model were performed to assess outcomes.

RESULTS: A total of 1065 outpatients were identified (mean±SD age, 67.9±13.9 years; 58% male). Baseline diastolic dysfunction was present in 770 patients (72.3%), with mild being the most prevalent. On follow-up testing (mean±SD, 1.1±0.4 years), 783 patients (73%) had stable, 168 (16%) had worsening, and 114 (11%) had improved baseline diastolic function. Eighty-eight patients (8.3%) had a decrease in left ventricular ejection fraction to

CONCLUSIONS: In patients with normal baseline left ventricular ejection fraction, worsening of diastolic function is an independent predictor of mortality.

PMID:

Low-Flow, Low-Gradient Severe Aortic Stenosis Despite Normal Ejection Fraction Is Associated With Severe Left Ventricular Dysfunction as Assessed by Speckle-Tracking Echocardiography: A Multicenter Study

OBJECTIVES: Low-flow low-gradient (LFLG) is sometimes observed in severe aortic stenosis (AS) despite normal ejection fraction, but its frequency and mechanisms are still debated.  We aimed to describe the characteristics of patients with LFLG AS and assess the presence of longitudinal left ventricular dysfunction in these patients.

METHODS: In a multicenter prospective study, 340 consecutive patients with severe AS and normal ejection fraction were studied.  Longitudinal left ventricular function was assessed by 2D-strain and global afterload by valvulo-arterial impedance.  Patients were classified according to flow and gradient: low flow was defined as a stroke volume index ≤35 mL/m(2), low gradient as a mean gradient ≤40 mm Hg.

RESULTS: Most patients (n=258, 75.9%) presented with high-gradient AS, and 82 patients (24.1%) with low-gradient AS.  Among the latter, 52 (15.3%) presented with normal flow and low gradient and 30 (8.8%) with LFLG.  As compared with normal flow and low gradient, patients with LFLG had more severe AS (aortic valve area=0.7±0.12 cm(2) versus 0.86±0.14 cm(2)), higher valvulo-arterial impedance (5.5±1.1 versus 4±0.8 mm Hg/mL/m(2)), and worse longitudinal left ventricular function (basal longitudinal strain=-11.6±3.4 versus -14.8±3%; P<0.001 for all).

CONCLUSIONS: LFLG AS is observed in 9% of patients with severe AS and normal ejection fraction and is associated with high global afterload and reduced longitudinal systolic function.  Patients with normal-flow low-gradient AS are more frequent and present with less severe AS, normal afterload, and less severe longitudinal dysfunction.  Severe left ventricular longitudinal dysfunction is a new explanation to the concept of LFLG AS.

PMID: 22109983

Resting Coronary Flow Velocity in the Functional Evaluation of Coronary Artery Stenosis: Study on Sequential Use of Computed Tomography Angiography and Transthoracic Doppler Echocardiography

OBJECTIVES: Accelerated flow at the site of flow-limiting stenosis can be detected by transthoracic Doppler echocardiography (TTDE). We studied feasibility and accuracy of sequential coronary computed tomography angiography (CTA) and TTDE in detection of haemodynamically significant coronary artery disease (CAD).

METHODS: We prospectively enrolled 107 patients with intermediate (30-70%) pre-test likelihood of CAD. All patients underwent CTA using a 64-slice scanner. Using TTDE, the ratio of maximal diastolic flow velocity to pre-stenotic flow velocity (M/P ratio) was measured in the coronary segments with stenosis in CTA. In all patients, the results were compared with invasive coronary angiography, including measurement of fractional flow reserve when appropriate. All analyses were done blinded.

RESULTS: TTDE was feasible in 276 of 285 evaluated coronary segments. Significant coronary stenoses were associated with a higher M/P ratio than non-significant stenoses (3.59 ± 1.82 vs. 1.28 ± 0.60, P < 0.001). The optimal M/P ratio for detection of significant stenosis was 2.2 (area under receiver operating characteristic curve 0.92, P < 0.001). Compared with the strategy of CTA alone, sequential CTA and focused TTDE had a better positive predictive value (PPV; 61 vs. 78%) and diagnostic accuracy (93 vs. 96%, P = 0.006) without impairment of the negative predictive value (97 vs. 97%).

CONCLUSIONS: Sequential use of CTA and TTDE is feasible for combined anatomic and functional evaluation of coronary stenoses. Compared with coronary CTA alone, addition of TTDE improved PPV for detection of significant CAD.

PMID: 21880607

Patient Management After Noninvasive Cardiac Imaging – Results From SPARC (Study of Myocardial Perfusion and Coronary Anatomy Imaging Roles in Coronary Artery Disease)

OBJECTIVES: This study examined short-term cardiac catheterization rates and medication changes after cardiac imaging. Noninvasive cardiac imaging is widely used in coronary artery disease, but its effects on subsequent patient management are unclear.

METHODS: We assessed the 90-day post-test rates of catheterization and medication changes in a prospective registry of 1,703 patients without a documented history of coronary artery disease and an intermediate to high likelihood of coronary artery disease undergoing cardiac single-photon emission computed tomography, positron emission tomography, or 64-slice coronary computed tomography angiography.

RESULTS: Baseline medication use was relatively infrequent. At 90 days, 9.6% of patients underwent catheterization. The rates of catheterization and medication changes increased in proportion to test abnormality findings. Among patients with the most severe test result findings, 38% to 61% were not referred to catheterization, 20% to 30% were not receiving aspirin, 35% to 44% were not receiving a beta-blocker, and 20% to 25% were not receiving a lipid-lowering agent at 90 days after the index test. Risk-adjusted analyses revealed that compared with stress single-photon emission computed tomography or positron emission tomography, changes in aspirin and lipid-lowering agent use was greater after computed tomography angiography, as was the 90-day catheterization referral rate in the setting of normal/nonobstructive and mildly abnormal test results.

CONCLUSIONS: Overall, noninvasive testing had only a modest impact on clinical management of patients referred for clinical testing. Although post-imaging use of cardiac catheterization and medical therapy increased in proportion to the degree of abnormality findings, the frequency of catheterization and medication change suggests possible undertreatment of higher risk patients. Patients were more likely to undergo cardiac catheterization after computed tomography angiography than after single-photon emission computed tomography or positron emission tomography after normal/nonobstructive and mildly abnormal study findings.

PMID:

Clinical Outcome in Asymptomatic Severe Aortic Stenosis

OBJECTIVES: This study examined the clinical course of patients with asymptomatic severe aortic stenosis (AS) according to the new proposed aortic valve stenosis grading classification. The management of patients with asymptomatic severe AS remains controversial. Moreover, under the same denomination of severe AS, several entities might be identified according to transvalvular flow rates and pressure gradients, resulting in 4 flow-gradient patterns.

METHODS: Transthoracic echocardiography and measurement of B-type natriuretic peptide level from venous blood sample were performed in 150 consecutive patients with asymptomatic severe AS and normal exercise test. Patients were classified in 4 groups, depending on left ventricular flow state (normal flow [NF] vs. low flow [LF]: 35 ml/m2) and pressure gradient levels (low gradient [LG] vs. high gradient [HG]: 40 mm Hg).

RESULTS: Patients with NF/LG had significantly lower B-type natriuretic peptide than those with LF/HG and LF/LG. The mean follow-up was 27 ± 12 months. At 2 years, cardiac event-free survival was 83 ± 6%, 44 ± 6%, 30 ± 12%, and 27 ± 13% in NF/LG, NF/HG, LF/HG, and LF/LG groups, respectively (p < 0.0001). On multivariable analysis, LF/LG (hazard ratio [HR]: 5.26, 95% confidence interval [CI]: 2.04 to 14.3, p = 0.045) and LF/HG (HR: 2.38, 95% CI: 1.02 to 5.55, p = 0.001) were identified as strong independent determinants of poor prognosis as compared with NF/HG. By limiting the multivariable analysis to patients with LF, LF/LG was an independent predictor of markedly reduced cardiac event-free survival when compared with LF/HG (HR: 5.4, 95% CI: 1.03 to 28.6, p = 0.046).

CONCLUSIONS: The use of the new proposed AS grading classification integrating valve area and flow-gradient patterns allows a better characterization of the clinical outcome of patients with asymptomatic severe AS.

PMID:

Percutaneous Transvenous Melody Valve-in-Ring Procedure for Mitral Valve Replacement

OBJECTIVES: The purpose of this study was to demonstrate the feasibility of percutaneous transvenous mitral valve-in-ring (VIR) implantation using the Melody valve in an ovine model. The recurrence of mitral regurgitation following surgical mitral valve (MV) repair in both adult and pediatric patients remains a significant clinical problem. Mitral annuloplasty rings are commonly used in MV repair procedures and may serve as secure landing zones for percutaneous valves.

METHODS: Five sheep underwent surgical MV annuloplasty (24 mm, n = 2; 26 mm, n = 2; 28 mm, n = 1). Animals underwent cardiac catheterization with VIR implantation via a transfemoral venous, transatrial septal approach 1 week following surgery. Hemodynamic, angiographic, and echocardiographic data were recorded before and after VIR.

RESULTS: VIR was technically successful and required <1 h of procedure time in all animals. Fluoroscopy demonstrated securely positioned Melody valves within the annuloplasty ring in all animals. Angiography revealed no significant MV regurgitation in 4 and moderate central MV regurgitation in the animal with the 28-mm annuloplasty. All animals demonstrated vigorous left ventricular function, no outflow tract obstruction, and no aortic valve insufficiency.

CONCLUSIONS: This study demonstrated the feasibility of a purely percutaneous approach to MV replacement in patients with preexisting annuloplasty rings. This novel approach may be of particular benefit to patients with failed repair of ischemic mitral regurgitation and in pediatric patients with complex structural heart disease.

PMID: 22133846