Clinical use of cardiovascular magnetic resonance

Cardiac index: A superior parameter of cardiac function than left ventricular ejection fraction in risk stratification of hypertrophic cardiomyopathy

BACKGROUND

An appropriate indicator of cardiac function in the risk stratification of hypertrophic cardiomyopathy (HCM) patients is urgently needed. Cardiac index that reflects cardiac pumping function may be suitable.

OBJECTIVE

The purpose of this study was to investigate the clinical significance of reduced cardiac index in HCM patients.

METHODS

A total of 927 HCM patients were enrolled. The primary endpoint was cardiovascular death. The secondary endpoints were sudden cardiac death (SCD) and all-cause death. Combination models were constructed by adding reduced cardiac index and reduced left ventricular ejection fraction (LVEF) to the HCM risk-SCD model. Predictive accuracy was determined by C-statistics.

RESULTS

Reduced cardiac index was defined as cardiac index ≤2.42 L/min/m². During median follow-up of 4.3 years, 51 patients reached the endpoint. Reduced cardiac index independently increased the risk of cardiovascular death (adjusted hazard ratio [aHR] 2.976; P = .007), SCD (aHR 6.385; P = .001), and all-cause death (aHR 2.428; P = .010). By adding reduced cardiac index to the HCM risk-SCD model, the model C-statistic increased from 0.691 to 0.762, with an integrated discrimination improvement of 0.021 (P = .018) and a net reclassification improvement of 0.560 (P = .007). The addition of reduced LVEF failed to improve the original model. Better predictive accuracy for all endpoints was also indicated in reduced cardiac index than in reduced LVEF.

CONCLUSION

Reduced cardiac index is an independent predictor of poor prognoses in HCM patients. Combining reduced cardiac index rather than reduced LVEF improved the HCM risk-SCD stratification strategy. The reduced cardiac index showed better predictive accuracy than reduced LVEF for all endpoints.

Ultrasound Cardiac Output Monitor (USCOM™) Measurements Prove Unreliable Compared to Cardiac Magnetic Resonance Imaging in Adolescents with Cardiac Disease

The purpose of this stuy is to prospectively assess the reliability of the ultrasound cardiac output monitor (USCOM™) for measuring stroke volume index and predicting left ventricular outflow tract diameter in adolescents with heart disease. Sixty consecutive adolescents with heart disease attending a tertiary medical center underwent USCOM™ assessment immediately after cardiac magnetic resonance imaging. USCOM™ measured stroke volume index and predicted left ventricular outflow tract diameter were compared to cardiac magnetic resonance imaging-derived values using Bland-Altman analysis. Ten patients with an abnormal left ventricular outflow tract were excluded from the analysis. An adequate USCOM™ signal was obtained in 49/50 patients. Mean stroke volume index was 46.1 ml/m² by the USCOM™ (range 22-66.9 ml/m²) and 42.9 ml/m² by cardiac magnetic resonance imaging (range 24.7-59.9 ml/m²). The bias (mean difference) was 3.2 ml/m²; precision (± 2SD of differences), 17 ml/m²; and mean percentage error, 38%. The mean (± 2SD) left ventricular outflow tract diameter was 0.445 ± 0.536 cm smaller by the USCOM™ algorithm prediction than by cardiac magnetic resonance imaging. Attempted adjustment of USCOM™ stroke volume index using cardiac magnetic resonance imaging left ventricular outflow tract diameter failed to improve agreement between the two modalities (bias 28.4 ml/m², precision 44.1 ml/m², percentage error 77.3%). Our study raises concerns regarding the reliability of USCOM™ for stroke volume index measurement in adolescents with cardiac disease, which did not improve even after adjusting for its inaccurate left ventricular outflow tract diameter prediction.

Effect of Levothyroxine on Left Ventricular Ejection Fraction in Patients With Subclinical Hypothyroidism and Acute Myocardial Infarction: A Randomized Clinical Trial

IMPORTANCE

Thyroid hormones play a key role in modulating myocardial contractility. Subclinical hypothyroidism in patients with acute myocardial infarction is associated with poor prognosis.

OBJECTIVE

To evaluate the effect of levothyroxine treatment on left ventricular function in patients with acute myocardial infarction and subclinical hypothyroidism.

DESIGN, SETTING, AND PARTICIPANTS

A double-blind, randomized clinical trial conducted in 6 hospitals in the United Kingdom. Patients with acute myocardial infarction including ST-segment elevation and non-ST-segment elevation were recruited between February 2015 and December 2016, with the last participant being followed up in December 2017.

INTERVENTIONS

Levothyroxine treatment (n = 46) commencing at 25 µg titrated to aim for serum thyrotropin levels between 0.4 and 2.5 mU/L or identical placebo (n = 49), both provided in capsule form, once daily for 52 weeks.

MAIN OUTCOMES AND MEASURES

The primary outcome measure was left ventricular ejection fraction at 52 weeks, assessed by magnetic resonance imaging, adjusted for age, sex, type of acute myocardial infarction, affected coronary artery territory, and baseline left ventricular ejection fraction. Secondary measures were left ventricular volumes, infarct size (assessed in a subgroup [n = 60]), adverse events, and patient-reported outcome measures of health status, health-related quality of life, and depression.

RESULTS

Among the 95 participants randomized, the mean (SD) age was 63.5 (9.5) years, 72 (76.6%) were men, and 65 (69.1%) had ST-segment elevation myocardial infarction. The median serum thyrotropin level was 5.7 mU/L (interquartile range, 4.8-7.3 mU/L) and the mean (SD) free thyroxine level was 1.14 (0.16) ng/dL. The primary outcome measurements at 52 weeks were available in 85 patients (89.5%). The mean left ventricular ejection fraction at baseline and at 52 weeks was 51.3% and 53.8%, respectively, in the levothyroxine group compared with 54.0% and 56.1%, respectively, in the placebo group (adjusted difference in groups, 0.76% [95% CI, -0.93% to 2.46%]; P = .37). None of the 6 secondary outcomes showed a significant difference between the levothyroxine and placebo treatment groups. There were 15 (33.3%) and 18 (36.7%) cardiovascular adverse events in the levothyroxine and placebo groups, respectively.

CONCLUSIONS AND RELEVANCE

In this preliminary study involving patients with subclinical hypothyroidism and acute myocardial infarction, treatment with levothyroxine, compared with placebo, did not significantly improve left ventricular ejection fraction after 52 weeks. These findings do not support treatment of subclinical hypothyroidism in patients with acute myocardial infarction.

TRIAL REGISTRATION

isrctn.org Identifier: http://www.isrctn.com/ISRCTN52505169.

[Meta-analyses on measurement precision of non-invasive hemodynamic monitoring technologies in adults]

An ideal non-invasive monitoring system should provide accurate and reproducible measurements of clinically relevant variables that enables clinicians to guide therapy accordingly. The monitor should be rapid, easy to use, readily available at the bedside, operator-independent, cost-effective and should have a minimal risk and side effect profile for patients. An example is the introduction of pulse oximetry, which has become established for non-invasive monitoring of oxygenation worldwide. A corresponding non-invasive monitoring of hemodynamics and perfusion could optimize the anesthesiological treatment to the needs in individual cases. In recent years several non-invasive technologies to monitor hemodynamics in the perioperative setting have been introduced: suprasternal Doppler ultrasound, modified windkessel function, pulse wave transit time, radial artery tonometry, thoracic bioimpedance, endotracheal bioimpedance, bioreactance, and partial CO₂ rebreathing have been tested for monitoring cardiac output or stroke volume. The photoelectric finger blood volume clamp technique and respiratory variation of the plethysmography curve have been assessed for monitoring fluid responsiveness. In this manuscript meta-analyses of non-invasive monitoring technologies were performed when non-invasive monitoring technology and reference technology were comparable. The primary evaluation criterion for all studies screened was a Bland-Altman analysis. Experimental and pediatric studies were excluded, as were all studies without a non-invasive monitoring technique or studies without evaluation of cardiac output/stroke volume or fluid responsiveness. Most studies found an acceptable bias with wide limits of agreement. Thus, most non-invasive hemodynamic monitoring technologies cannot be considered to be equivalent to the respective reference method. Studies testing the impact of non-invasive hemodynamic monitoring technologies as a trend evaluation on outcome, as well as studies evaluating alternatives to the finger for capturing the raw signals for hemodynamic assessment, and, finally, studies evaluating technologies based on a flow time measurement are current topics of clinical research.

Short-Axis Diastolic Ventricular Area Ratio as a New Index in Screening Patients with Repaired Tetralogy of Fallot

Right ventricular (RV) end-diastolic volume measured by cardiovascular magnetic resonance imaging (CMR) is a criterion for pulmonary valve replacement in patients with tetralogy of Fallot (TOF). We sought to determine if the ratio of echocardiographic, short-axis RV-to-left ventricular (LV) end-diastolic areas (EDA) could be used to predict RV volume on CMR. We retrospectively reviewed the echocardiograms of all patients with repaired TOF who underwent CMR at our institution from 2011 to 2015 and also had an echocardiogram within 6 months of the CMR. The short-axis RV and LV EDAs were measured and the ratio of the two was calculated. Results were compared with CMR RV end-diastolic volume index (RVEDVi) and RV:LV end-diastolic volume ratio. The sensitivity and specificity values predicting RV volumes > 150 ml/m² were calculated. Fifty-eight studies met inclusion criteria. There were 47 studies with RVEDVi < 150 ml/m² and 11 with RVEDVi > 150 ml/m². RV:LV EDA and CMR RV:LV end-diastolic volume ratio correlated strongly (r = 0.76, p < 0.0001). An RV:LV EDA ≥ 1.57 had a 90% sensitivity to predict RVEDVi > 150 ml/m² (area under the curve = 0.74, 95% CI 1.5-27.9; p = 0.012). An RV:LV EDA ≥ 1.88 had an 81% specificity to detect RV volume index > 150 ml/m². Short-axis RV:LV EDA correlates well with an increased RVEDVi as measured by CMR. This new and simple measure can be used to predict optimal timing for CMR in anticipation of pulmonary valve replacement in repaired TOF.

Variability in Ejection Fraction Measured By Echocardiography, Gated Single-Photon Emission Computed Tomography, and Cardiac Magnetic Resonance in Patients With Coronary Artery Disease and Left Ventricular Dysfunction

IMPORTANCE

Clinical decisions are frequently based on measurement of left ventricular ejection fraction (LVEF). Limited information exists regarding inconsistencies in LVEF measurements when determined by various imaging modalities and the potential impact of such variability.

OBJECTIVE

To determine the intermodality variability of LVEF measured by echocardiography, gated single-photon emission computed tomography (SPECT), and cardiovascular magnetic resonance (CMR) in patients with left ventricular dysfunction.

DESIGN, SETTING, AND PARTICIPANTS

International multicenter diagnostic study with LVEF imaging performed at 127 clinical sites in 26 countries from July 24, 2002, to May 5, 2007, and measured by core laboratories. Secondary study of clinical diagnostic measurements of LVEF in the Surgical Treatment for Ischemic Heart Failure (STICH), a randomized trial to identify the optimal treatment strategy for patients with LVEF of 35% or less and coronary artery disease. Data analysis was conducted from March 19, 2016, to May 29, 2018.

MAIN OUTCOMES AND MEASURES

At baseline, most patients had an echocardiogram and subsets of patients underwent SPECT and/or CMR. Left ventricular ejection fraction was measured by a core laboratory for each modality independent of the results of other modalities, and measurements were compared among imaging methods using correlation, Bland-Altman plots, and coverage probability methods. Association of LVEF by each method and death was assessed.

RESULTS

A total of 2032 patients (mean [SD] age, 60.9 [9.6] years; 1759 [86.6%] male) with baseline LVEF data were included. Correlation of LVEF between modalities was r = 0.601 (for biplane echocardiography and SPECT [n = 385]), r = 0.493 (for biplane echocardiography and CMR [n = 204]), and r = 0.660 (for CMR and SPECT [n = 134]). Bland-Altman plots showed only moderate agreement in LVEF measurements from all 3 core laboratories with no substantial overestimation or underestimation of LVEF by any modality. The percentage of observations that fell within a range of 5% ranged from 43% to 54% between different imaging modalities.

CONCLUSIONS AND RELEVANCE

In this international multicenter study of patients with coronary artery disease and reduced LVEF, there was substantial variation between modalities in LVEF determination by core laboratories. This variability should be considered in clinical management and trial design.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT00023595.

Computed tomography of cardiomyopathies

Cardiac computed tomography (CT) is increasingly used in the evaluation of cardiomyopathies, particularly in patients who are not able to undergo other non-invasive imaging tests such as magnetic resonance imaging (MRI) due to the presence of MRI-incompatible pacemakers/defibrillators or other contraindications or due to extensive artifacts from indwelling metallic devices. Advances in scanner technology enable acquisition of CT images with high spatial resolution, good temporal resolution, wide field of view and multi-planar reconstruction capabilities. CT is useful in cardiomyopathies in several ways, particularly in the evaluation of coronary arteries, characterization of cardiomyopathy phenotype, quantification of cardiac volumes and function, treatment-planning, and post-treatment evaluation. In this article, we review the imaging techniques and specific applications of CT in the evaluation of cardiomyopathies.

Comparison of the Therapeutic Effects of Acupuncture at PC6 and ST36 for Chronic Myocardial Ischemia

We aimed to compare the differences of the effects on chronic myocardial ischemia (MI) of acupuncture at PC6 and ST36. The chronic MI model of minipigs was created by implanting an Ameroid constrictor on the left anterior descending coronary artery (LAD) and then two weeks' acupuncture was stimulated at PC6 or ST36, respectively. The results showed that both acupoints' stimulation decreased the serous cardiac troponin T (cTnT) and ischemia modified albumin (IMA) significantly and improved the ischemic ECG changes. The amplitude of pathological Q wave in the PC6 group decreased more significantly than that of the ST36 group. The cardiovascular magnetic resonance imaging (cMRI) results showed that the decreased left ventricular ejection fraction (LVEF) was not improved obviously in both groups. The left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) enlarged progressively even after acupuncture. The left ventricular wall mass (LVWM) in the ST36 group increased more obviously than that of the PC6 group, which paralleled the decreasing angiotensin II (Ang II) concentration in the plasma. These results suggested that acupuncture at PC6 or ST36 was effective for protecting the myocardium from chronic ischemic injury, and the effect of PC6 seemed to be better.

Comparison of bioreactance non-invasive cardiac output measurements with cardiac magnetic resonance imaging

Impedance cardiography measurement of cardiac output gained wide interest due to its ease of use and non-invasiveness. However, validation studies of different algorithms yielded diverging results. Bioreactance (BR) as a recent adaption differs fundamentally as the flow signal is derived from phase shifts. Our aim was to assess the accuracy and reproducibility of BR, as compared to the non-invasive gold standard--cardiac magnetic resonance imaging (CMR). We prospectively included 32 stable patients. BR was performed twice in the supine position and averaged over 30 seconds. Mean bias was 0.2 ± 1.8 l/minute (1 ± 28%, percentage error 55%) with limits of agreement ranging from  -3.4 to 3.7 l/minute. Reproducibility was acceptable with a mean bias of 0.1 ± 0.9 l/minute (1 ± 14%, 27%). Low cardiac output was significantly overestimated (-1.1 ± 1.5 l/minute), while high cardiac output was underestimated (1.5 ± 1.7 l/minute), (P=0.001), although reproducibility was unaffected. Bias and weight were moderately correlated in men (r = 0.50, P=0.02). No differences for accuracy were found in nine patients who had an arrhythmia (0.3 ± 1.4 versus 0.1 ± 2.0 l/minute, P=0.76), while clinically relevant differences were found in patients with mild aortic valve disease (1.9 ± 2.2 versus -0.3 ± 1.7 l/minute, P=0.02). Overall, BR showed insufficient agreement with CMR, overestimating low and underestimating high cardiac output states. Reproducibility was acceptable and not negatively affected by the circulatory condition. Consequently, absolute values acquired with BR should be interpreted with caution and must not be used interchangeably in clinical practice.

Incidental findings in cardiac magnetic resonance imaging: superiority of bSSFP over T1w-HASTE for extra-cardiac findings assessment

Incidental findings are frequent in radiological examinations and may have an impact on further patient management. The aim of this retrospective study was to analyze, which of two thoracic scout sequences is more suitable for detecting incidental extra-cardiac findings at cardiac magnetic resonance imaging (CMRI) with stress perfusion. During a 14-month period clinically indicated stress perfusion CMRI was performed in 97 consecutive patients. For anatomical orientation ECG-triggered (electrocardiography) T1w-Half-fourier acquisition single-shot turbo spin-echo (HASTE) and balanced steady state free precession (bSSFP) sequences were performed for planning the standard cardiac sequences. Two radiologists independently studied incidental extra-cardiac findings with both sequences and rated the diagnostic confidence of the sequences for this assessment using a multinomial model. Furthermore, the interobserver agreement between the observers was assessed by weighted kappa statistics. Eight patients without incidental findings were excluded. In the other 89 patients a total of 153 incidental extra-cardiac findings were observed. Overall, 47.1% of findings were seen with better diagnostic confidence at bSSFP as opposed to 20.6% at T1w-HASTE. 32.4% of findings were equally well seen with both sequences. Consequently the bSSFP sequence was significantly better in terms of diagnostic confidence for detecting the majority of extra-cardiac incidental findings (P < 0.01), whereas a minority of findings was better visible by the HASTE sequence. The weighted kappa statistics was 0.85, indicating good interobserver agreement. Compared with T1w-HASTE, the bSSFP sequence improved the visibility of incidental extra-cardiac findings at stress perfusion CMRI. While all findings were seen on both sequences, bSSFP resulted in improved diagnostic confidence, and the T1w-HASTE sequence provided complementary diagnostic information in only a minority of patients.

Cell therapy for heart disease after 15 years: Unmet expectations

Over the past two decades cardiac cell therapy (CCT) has emerged as a promising new strategy to cure heart diseases at high unmet need. Thousands of patients have entered clinical trials for acute or chronic heart conditions testing different cell types, including autologous or allogeneic bone marrow (BM)-derived mononuclear or selected cells, BM- or adipose tissue-derived mesenchymal cells, or cardiac resident progenitors based on their potential ability to regenerate scarred or dysfunctional myocardium. Nowadays, the original enthusiasm surrounding the regenerative medicine field has been cushioned by a cumulative body of evidence indicating an inefficient or modest efficacy of CCT in improving cardiac function, along with the continued lack of indisputable proof for long-term prognostic benefit. In this review, we have firstly comprehensively outlined the positive and negative results of cell therapy studies in patients with acute myocardial infarction, refractory angina and chronic heart failure. Next, we have discussed cell therapy- and patient-related variables (e.g. cell intrinsic and extrinsic characteristics as well as criteria of patient selection and proposed methodologies) that might have dampened the efficacy of past cell therapy trials. Finally, we have addressed critical factors to be considered before embarking on further clinical trials.

Position Paper of the European Society of Cardiology Working Group Cellular Biology of the Heart: cell-based therapies for myocardial repair and regeneration in ischemic heart disease and heart failure

Despite improvements in modern cardiovascular therapy, the morbidity and mortality of ischaemic heart disease (IHD) and heart failure (HF) remain significant in Europe and worldwide. Patients with IHD may benefit from therapies that would accelerate natural processes of postnatal collateral vessel formation and/or muscle regeneration. Here, we discuss the use of cells in the context of heart repair, and the most relevant results and current limitations from clinical trials using cell-based therapies to treat IHD and HF. We identify and discuss promising potential new therapeutic strategies that include ex vivo cell-mediated gene therapy, the use of biomaterials and cell-free therapies aimed at increasing the success rates of therapy for IHD and HF. The overall aim of this Position Paper of the ESC Working Group Cellular Biology of the Heart is to provide recommendations on how to improve the therapeutic application of cell-based therapies for cardiac regeneration and repair.

Myocardial Fibrosis and Left Ventricular Dysfunction in Duchenne Muscular Dystrophy Carriers Using Cardiac Magnetic Resonance Imaging

The goal of our study was to characterize the degree of myocardial fibrosis and left ventricular dysfunction in our cohort of Duchenne muscular dystrophy (DMD) carriers using cardiac magnetic resonance imaging (CMR). Seventy percent of males with DMD have mothers who are carriers of the Xp21 mutation. Carrier phenotypic characteristics range from asymptomatic to left ventricular (LV) dysfunction and cardiomyopathy. The true prevalence of cardiac involvement in DMD carriers is unknown. We performed a retrospective observational study. All female DMD carriers who underwent clinical CMR studies at Cincinnati Children's Hospital Medical Center from December 6, 2006, to August 28, 2013, were evaluated. Patients underwent standard CMR assessment with LV function assessment and late gadolinium enhancement (LGE). In addition, offline feature tracking strain analysis was performed on the basal, mid, and apical short axis. Twenty-two patients were studied, of which 20 underwent adequate testing for myocardial LGE. Four of 22 patients (18 %) were found to have LV dysfunction (ejection fraction <55 %). Seven of 20 DMD carriers (35 %) were found to have LGE. The patients with evidence of LGE had an overall trend to lower absolute deformation parameters; however, this did not meet statistical significance when correcting for multiple comparisons. Our study demonstrates a high rate of LGE as well as LV dysfunction in DMD carriers. Cardiovascular and musculoskeletal symptoms were not statistically different between those with and without cardiac involvement. This study demonstrates the importance of surveillance CMR evaluation of DMD carriers.

Thyroxine in acute myocardial infarction (ThyrAMI) - levothyroxine in subclinical hypothyroidism post-acute myocardial infarction: study protocol for a randomised controlled trial

BACKGROUND

Cardiac disease is the most common cause of morbidity and mortality in the United Kingdom. Even minor changes in thyroid hormone concentration may impact adversely on the cardiovascular system. Subclinical hypothyroidism (SCH) after admission for an acute cardiac problem has been associated with an increase in cardiac mortality and overall death. We have designed protocols for a prospective observational study to assess the association of thyroid function at the time of acute myocardial infarction (AMI) with cardiovascular outcomes, and a double-blinded randomised placebo-controlled trial of levothyroxine to evaluate its effect on LV function and vascular health.

METHODS/DESIGN

ThyrAMI 1: This will be a prospective longitudinal observational study of patients with AMI that will be followed for 24 months to study the association between thyroid status at the time of AMI (within 24 hours of diagnosis) with vascular outcomes. ThyrAMI 2: This will be a prospective double-blinded randomised placebo-controlled trial of levothyroxine of 12 months duration in patients with AMI and SCH.

SETTING

Patients will be recruited from five hospitals in the North East of England.

PARTICIPANTS

One hundred patients with thyroid function tests within the subclinical hypothyroid range upon admission with an AMI and no previous history of thyroid disease.

INTERVENTION

Levothyroxine will be administered at a starting dose of 25 mcg once daily, which will be increased at intervals if needed to maintain a TSH level between 0.4 to 2.5 mU/L, versus a placebo.

RANDOMISATION

Participants will be randomized with a computerised randomisation algorithm, stratified by type of MI (NSTEMI versus STEMI), in a 1:1 ratio to levothyroxine therapy or placebo (as container or bottle numbers), starting within 21 (+/- 7) days of AMI.

BLINDING

Assignment to either the LT4 or placebo arm will be double-blinded.

OUTCOMES

The outcome will be the effect of levothyroxine on ventricular function, endothelial function and blood coagulability and rheology.

DISCUSSION

There is evidence to suggest that treatment of SCH can improve cardiovascular parameters. Therefore, ThyrAMI 1 and ThyrAMI 2 will be the first trials investigating SCH in AMI to give a better insight into whether thyroid hormone levels are a key target for improving cardiovascular outcomes.

TRIAL REGISTRATION

ISRCTN number: ISRCTN52505169 . Date of registration: 09/01/2015.

Right ventricle-pulmonary circulation dysfunction: a review of energy-based approach

Patients with repaired or palliated right heart congenital heart disease (CHD) are often left with residual lesions that progress and can result in significant morbidity. However, right ventricular-pulmonary arterial evaluation and the timing of reintvervention is still subjective. Currently, it relies on symptomology, or RV imaging-based metrics from echocardiography or MR derived parameters including right ventricular (RV) ejection fraction (EF), end-systolic pressure (ESP), and end-diastolic volume (EDV). However, the RV is coupled to the pulmonary vasculature, and they are not typically evaluated together. For example, the dysfunctional right ventricular-pulmonary circulation (RV-PC) adversely affects the RV myocardial performance resulting in decreased efficiency. Therefore, comprehensive hemodynamic assessment should incorporate changes in RV-PC and energy efficiency for CHD patients. The ventricular pressure-volume relationship (PVR) and other energy-based endpoints derived from PVR, such as stroke work (SW) and ventricular elastance (Ees), can provide a measure of RV performance. However, a detailed explanation of the relationship between RV performance and pulmonary arterial hemodynamics is lacking. More importantly, PVR is impractical for routine longitudinal evaluation in a clinical setting, because it requires invasive catheterization. As an alternative, analytical methods and computational fluid dynamics (CFD) have been used to compute energy endpoints, such as power loss or energy dissipation, in abnormal physiologies. In this review, we review the causes of RV-PA failure and the limitation of current clinical parameters to quantify RV-PC dysfunction. Then, we describe the advantage of currently available energy-based endpoints and emerging energy endpoints, such as energy loss in the Pas or kinetic energy, obtained from a new non-invasive imaging technique, i.e. 4D phase contrast MRI.

Regional circumferential strain is a biomarker for disease severity in duchenne muscular dystrophy heart disease: a cross-sectional study

The aim of this study is to determine the contribution of strain ε cc in mid left ventricular (LV) segments to the reduction of composite LV circumferential ε cc in assess severity of duchenne muscular dystrophy (DMD) heart disease as assessed by cardiac magnetic resonance imaging (CMR). DMD patients and control subjects were stratified by age, LV ejection fraction, and late gadolinium enhancement (LGE) status. Tagged CMR images were analyzed for global ventricular function, LGE imaging, and composite and segmental ε cc. The relationship between changes in segmental ε cc changes and LGE across patient groups was assessed by a statistical step-down model. LV ε cc exhibited segmental heterogeneity; in control subjects and young DMD patients, ε cc was greatest in LV lateral free wall segments. However, with increasing age and cardiac disease severity as demonstrated by decreased EF and development of myocardial strain the segmental differences diminished. In subjects with advanced heart disease as evidenced by reduced LV ejection fraction and presence of LGE, very little segmental heterogeneity was present. In control subjects and young DMD patients, ε cc was greatest in LV lateral free wall segments. Increased DMD heart disease severity was associated with reduced composite; ε cc diminished regional ε cc heterogeneity and positive LGE imaging. Taken together, these findings suggest that perturbation of segmental, heterogeneous ε cc is an early biomarker of disease severity in this cross-section of DMD patients.

Quantitative magnetic resonance imaging of pulmonary hypertension: a practical approach to the current state of the art

Pulmonary hypertension is a condition of varied etiology, commonly associated with poor clinical outcome. Patients are categorized on the basis of pathophysiological, clinical, radiologic, and therapeutic similarities. Pulmonary arterial hypertension (PAH) is often diagnosed late in its disease course, with outcome dependent on etiology, disease severity, and response to treatment. Recent advances in quantitative magnetic resonance imaging (MRI) allow for better initial characterization and measurement of the morphologic and flow-related changes that accompany the response of the heart-lung axis to prolonged elevation of pulmonary arterial pressure and resistance and provide a reproducible, comprehensive, and noninvasive means of assessing the course of the disease and response to treatment. Typical features of PAH occur primarily as a result of increased pulmonary vascular resistance and the resultant increased right ventricular (RV) afterload. Several MRI-derived diagnostic markers have emerged, such as ventricular mass index, interventricular septal configuration, and average pulmonary artery velocity, with diagnostic accuracy similar to that of Doppler echocardiography. Furthermore, prognostic markers have been identified with independent predictive value for identification of treatment failure. Such markers include large RV end-diastolic volume index, low left ventricular end-diastolic volume index, low RV ejection fraction, and relative area change of the pulmonary trunk. MRI is ideally suited for longitudinal follow-up of patients with PAH because of its noninvasive nature and high reproducibility and is advantageous over other biomarkers in the study of PAH because of its sensitivity to change in morphologic, functional, and flow-related parameters. Further study on the role of MRI image based biomarkers in the clinical environment is warranted.

Improved diagnosis and prognosis using Decisions Informed by Combining Entities (DICE): results from the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE)

OBJECTIVES

To introduce an algorithmic approach to improve the interpretation of myocardial perfusion images in women with suspected myocardial ischemia.

BACKGROUND

Gated single photon emission computed tomography (SPECT) and magnetic resonance (MR) myocardial perfusion imaging (MPI) approaches have relatively poor diagnostic and prognostic value in women with suspected myocardial ischemia. Here we introduce an approach: Decisions Informed by Combining Entities (DICE) that forms a mathematical model utilizing MPI and cardiac dimensions generated by one modality to predict the perfusion status of another modality. The effect of the model is to systematically incorporate cardiac metrics that influence the interpretation of perfusion images, leading to greater consistency in designation of myocardial perfusion status between studies.

METHODS

Women (n=213), with suspected myocardial ischemia, underwent MPI assessment for regional perfusion defects using two modalities: gated SPECT (n=207) and MR imaging (n=203). To determine perfusion status, MR data were evaluated qualitatively and semi-quantitatively while SPECT data were evaluated using conventional clinical criteria. These perfusion status readings were designated "Original". Four regression models were generated to model perfusion status obtained with one modality [e.g., semi-quantitative magnetic resonance imaging (MRI)] against another modality (e.g., SPECT) and a threshold applied (DICE modeling) to designate perfusion status as normal or low. The DICE models included perfusion status, left ventricular (LV) chamber volumes and myocardial wall thickness. Women were followed for 40±16 months for the development of first major adverse cardiovascular event (MACE: CV death, nonfatal myocardial infarction (MI) or hospitalization for congestive heart failure). Original and DICE perfusion status were compared in their ability to detect high-grade coronary artery disease (CAD) and for prediction of MACE.

RESULTS

Adverse events occurred in 25 (12%) women and CAD was present in 34 (16%). In receiver-operator characteristic (ROC) analysis for CAD detection, the average area under the curve (AUC) for DICE vs. Original status was 0.77±0.03 vs. 0.70±0.03, P<0.01. Similarly, in Kaplan-Meier survival analysis the average log-rank statistic was higher for DICE vs. the Original readings (10.6±5.2 vs. 3.0±0.6, P<0.05).

CONCLUSIONS

While two data sets are required to generate the DICE models no knowledge of follow-up results is needed. DICE modeling improved diagnostic and prognostic value vs. the Original interpretation of the myocardial perfusion status.

Left ventricular noncompaction in Duchenne muscular dystrophy

BACKGROUND

Left ventricular noncompaction (LVNC) describes deep trabeculations in the left ventricular (LV) endocardium and a thinned epicardium. LVNC is seen both as a primary cardiomyopathy and as a secondary finding in other syndromes affecting the myocardium such as neuromuscular disorders. The objective of this study is to define the prevalence of LVNC in the Duchenne Muscular Dystrophy (DMD) population and characterize its relationship to global LV function.

METHODS

Cardiac magnetic resonance (CMR) was used to assess ventricular morphology and function in 151 subjects: DMD with ejection fraction (EF) > 55% (n = 66), DMD with EF < 55% (n = 30), primary LVNC (n = 15) and normal controls (n = 40). The non-compacted to compacted (NC/C) ratio was measured in each of the 16 standard myocardial segments. LVNC was defined as a diastolic NC/C ratio > 2.3 for any segment.

RESULTS

LVNC criteria were met by 27/96 DMD patients (prevalence of 28%): 11 had an EF > 55% (prevalence of 16.7%), and 16 had an EF < 55% (prevalence of 53.3%). The median maximum NC/C ratio was 1.8 for DMD with EF > 55%, 2.46 for DMD with EF < 55%, 1.54 for the normal subjects, and 3.69 for primary LVNC patients. Longitudinal data for 78 of the DMD boys demonstrated a mean rate of change in NC/C ratio per year of +0.36.

CONCLUSION

The high prevalence of LVNC in DMD is associated with decreased LV systolic function that develops over time and may represent muscular degeneration versus compensatory remodeling.

Prevalence and clinical relevance of extracardiac findings at cardiac MRI

PURPOSE

To assess the incidence of extracardiac findings in patients undergoing clinical cardiac magnetic resonance imaging (CMRI) of the heart, and to determine the influence of those findings on patient management.

MATERIALS AND METHODS

During 40 months, 854 CMRI were performed at 1.5 T. Extracardiac findings were classified as significant (group A), if recommended for additional diagnostics or therapeutic interventions, and as nonsignificant (group B).

RESULTS

The most frequent indication for CMRI was evaluation of cardiac stress ischemia. In all, 631 CMRI (74% of 854) showed no extracardiac pathologies. In the remaining 223 CMRI (26% of 854), a total of 286 extracardiac findings were detected. Among these findings, 49 were considered significant (group A) and 237 nonsignificant (group B). In group A, the most common findings were suspicious pulmonary nodules or masses. In group B, the most frequent findings were hepatic cysts or hemangiomas. Eight malignancies were observed with certainty at CMRI. Seven of them had been incidentally diagnosed on CMRI for the first time, and subsequently changed the patients' management.

CONCLUSION

Extracardiac findings in clinically indicated CMRI are common (about 26%). Radiologists and cardiologists should be aware of relevant extracardiac findings that might require additional diagnostics or treatment.

Association of QRS duration with left ventricular structure and function and risk of heart failure in middle-aged and older adults: the Multi-Ethnic Study of Atherosclerosis (MESA)

AIMS

Prolonged QRS duration (QRSd) on the electrocardiogram (ECG) has been associated with cardiac structural and functional abnormalities by echocardiography and an increased risk of heart failure (HF). Data are sparse on these relationships in middle-aged and elderly individuals free of baseline cardiovascular disease with respect to cardiac magnetic resonance imaging (MRI). We sought to determine whether QRSd is associated with incident HF and measures of cardiac structure and function by cardiac MRI.

METHODS AND RESULTS

We analysed baseline ECGs in the Multi-Ethnic Study of Atherosclerosis (MESA) to determine whether QRSd >100 ms was associated with incident HF. We adjusted for demographic and clinical risk factors, as well as MRI measures of left ventricular (LV) structure and function. Among 4591 eligible participants (51% women; 39% white; mean age 61 years), 75 developed incident HF over a mean follow-up of 7.1 years. QRSd >100 ms was significantly associated with MRI measures of cardiac structure and function, as well as incident HF, even after adjustment for demographic covariates [hazard ratio (HR) 2.10, 95% confidence interval (CI) 1.29-3.42; P = 0.003] and clinical risk factors (HR 1.86, 95% CI 1.14-3.03; P = 0.01). With further adjustment for individual LV structural measures, findings were attenuated to non-significance. Separate adjustment for LV functional measures yielded only mild attenuation.

CONCLUSION

In middle-aged and older adults without cardiovascular disease, a QRSd >100 ms was significantly associated with incident HF. After adjustment for LV structural measures, the association was attenuated to non-significance, suggesting that prolonged QRSd is potentially a useful marker of LV structure that may predispose to HF risk.

Influence of baseline left ventricular function on the clinical outcome of surgical ventricular reconstruction in patients with ischaemic cardiomyopathy

AIMS

The Surgical Treatment for Ischemic Heart Failure (STICH) trial demonstrated no overall benefit when surgical ventricular reconstruction (SVR) was added to coronary artery bypass grafting (CABG) in patients with ischaemic cardiomyopathy. The present analysis was to determine whether, based on baseline left ventricular (LV) function parameters, any subgroups could be identified that benefited from SVR.

METHODS AND RESULTS

Among the 1000 patients enrolled, Core Lab measures of baseline LV function with adequate quality were obtained in 710 patients using echocardiography, in 352 using cardiovascular magnetic resonance, and in 344 using radionuclide imaging. The relationship between LV end-systolic volume index (ESVI), end-diastolic volume index, ejection fraction (EF), regional wall motion abnormalities, and outcome were first assessed only by echocardiographic measures, and then by 13 algorithms using a different hierarchy of imaging modalities and their quality. The median ESVI and EF were 78.0 (range: 22.8-283.8) mL/m2 and 28.0%, respectively. Hazard ratios comparing the randomized arms by subgroups of LVESVI and LVEF measured by echocardiography found that patients with smaller ventricles (LVESVI <60 mL/m2) and better LVEF (≥33%) may have benefitted by SVR, while those with larger ventricles (LVESVI >90 mL/m(2)) and lower LVEF (≤25%) did worse with SVR. Algorithms using all three imaging modalities found a weaker relationship between LV global function and the effects of SVR. The extent of regional wall motion abnormality did not influence the effects of SVR.

CONCLUSIONS

Subgroup analyses of the STICH trial suggest that patients with less dilated LV and better LVEF may benefit from SVR, while those with larger LV and poorer LVEF may do worse. Clinical Trial Registration #: NCT00023595.

Effects of steroids and angiotensin converting enzyme inhibition on circumferential strain in boys with Duchenne muscular dystrophy: a cross-sectional and longitudinal study utilizing cardiovascular magnetic resonance

BACKGROUND

Steroid use has prolonged ambulation in Duchenne muscular dystrophy (DMD) and combined with advances in respiratory care overall management has improved such that cardiac manifestations have become the major cause of death. Unfortunately, there is no consensus for DMD-associated cardiac disease management. Our purpose was to assess effects of steroid use alone or in combination with angiotensin converting enzyme inhibitors (ACEI) or angiotension receptor blocker (ARB) on cardiovascular magnetic resonance (CMR) derived circumferential strain (εcc).

METHODS

We used CMR to assess effects of corticosteroids alone (Group A) or in combination with ACEI or ARB (Group B) on heart rate (HR), left ventricular ejection fraction (LVEF), mass (LVM), end diastolic volume (LVEDV) and circumferential strain (εcc) in a cohort of 171 DMD patients >5 years of age. Treatment decisions were made independently by physicians at both our institution and referral centers and not based on CMR results.

RESULTS

Patients in Group A (114 studies) were younger than those in Group B (92 studies)(10 ± 2.4 vs. 12.4 ± 3.2 years, p < 0.0001), but HR, LVEF, LVEDV and LVM were not different. Although εcc magnitude was lower in Group B than Group A (-13.8 ± 1.9 vs. -12.8 ± 2.0, p = 0.0004), age correction using covariance analysis eliminated this effect. In a subset of patients who underwent serial CMR exams with an inter-study time of ~15 months, εcc worsened regardless of treatment group.

CONCLUSIONS

These results support the need for prospective clinical trials to identify more effective treatment regimens for DMD associated cardiac disease.

A comparative evaluation of electrical velocimetry and inert gas rebreathing for the non-invasive assessment of cardiac output

BACKGROUND

When assessing the function of the cardiovascular system, cardiac output (CO) is a substantial parameter. For its determination, numerous non-invasive techniques have been proposed in the recent years including inert gas rebreathing (IGR) and impedance cardiography (ICG). The aim of our study was to evaluate whether a novel ICG algorithm (electrical velocimetry) and IGR can be used interchangeably in the clinical setting.

METHODS

A total of 120 consecutive stable patients were included resulting in two pairs of repeated non-invasive cardiac output measurements.

RESULTS

The mean CO was 5.0 ± 1.2 l/min (range 2.6-8.6 l/min) using IGR and 4.4 ± 1.1 l/min (1.7-7.4 l/min) using ICG, respectively. Bland-Altman analysis revealed an acceptable agreement with a mean bias of 0.6 ± 1.2 l/min. We found a high reproducibility with a mean bias of 0.2 ± 0.7 l/min for IGR and 0.0 ± 0.3 l/min for ICG (p < 0.001), respectively. There was a statistically significant difference for unphysiological circulatory conditions represented by values of 2.6-4.1 l/min and 5.6-8.6 l/min.

CONCLUSIONS

Both non-invasive techniques are associated with low operating costs and require only a few expendable items for the rapid determination of cardiac function. We found an acceptable agreement between IGR and ICG as well as a high reproducibility, which was statistically significant higher for ICG. For cardiac output states exceeding the physiological range, we found a statistically significant difference. Consequently, values of cardiac function determined by either method should not be used interchangeably in the clinical setting.

Late gadolinium enhancement on cardiac magnetic resonance and phenotypic expression in hypertrophic cardiomyopathy

BACKGROUND

Cardiac magnetic resonance (CMR) imaging with late gadolinium enhancement (LGE) can identify areas of myocardial fibrosis in vivo in patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to examine the association between clinical-morphological variables, risk factor for sudden death, and LGE findings in a consecutive, unselected population of HCM patients.

METHODS

From January 2005 to August 2009, 124 HCM patients (53 ± 17 years, 86 men) were prospectively evaluated with CMR examination, assessing left ventricular (LV) hypertrophy, function, and LGE.

RESULTS

In univariate analysis, patients were divided into tertiles according to the number of segments positive for LGE (first tertile, 0.3 ± 0.4; second tertile, 2.2 ± 0.4; third tertile, 5.2 ± 1.9 segments). Male gender (P = .05), maximum LV wall thickness (P = .002), nonsustained ventricular tachycardia (P = .001), ejection fraction <50% (P = .02), LV mass (P = .02), left atrium dilation (P = .04), perfusion defects (P ≤ .001), and telesystolic volume (P = .04) were all positively related with the number of segments of LGE. In multivariable analysis, male gender (P = .007), maximum LV wall thickness (P = .006), LV mass (P = .031), and perfusion alterations (P = .017) were independent predictors of LGE extent.

CONCLUSIONS

Our study shows an independent association, even at multivariate analysis, between the entity of LGE and maximum LV wall thickness, mass, and perfusion defects in patients with HCM. Whether the presence and the extent of LGE translates into clinical events later on awaits further long-term follow-up studies.

An inter-landmark approach to 4-D shape extraction and interpretation: application to myocardial motion assessment in MRI

This paper presents a novel approach to shape extraction and interpretation in 4-D cardiac magnetic resonance imaging data. Statistical modeling of spatiotemporal interlandmark relationships is performed to enable the decomposition of global shape constraints and subsequently of the image analysis tasks. The introduced descriptors furthermore provide invariance to similarity transformations and thus eliminate pose estimation errors in the presence of image artifacts or geometrical inconsistencies. A set of algorithms are derived to address key technical issues related to constrained boundary tracking, dynamic model relaxation, automatic initialization, and dysfunction localization. The proposed framework is validated with a relatively large dataset of 50 subjects and compared to existing statistical shape modeling methods. The results indicate increased adaptation to spatiotemporal variations and imaging conditions.

A novel noninvasive ultrasonic cardiac output monitor: comparison with cardiac magnetic resonance

BACKGROUND

USCOM, a novel continuous wave Doppler (CWD) device, has been introduced for noninvasive determination of cardiac output (CO). The present study aimed to compare the accuracy and reproducibility of the new device, using cardiovascular magnetic resonance imaging (CMR) as the noninvasive gold standard.

METHODS AND RESULTS

The CO of 56 consecutive patients was prospectively determined by CWD either before or after CMR imaging. The CWD probe was placed in the suprasternal or supraclavicular notch aiming at the aortic valve. Valid CWD signals could be obtained in 45 patients yielding a CO of 5.3+/-1.1 L/min (range, 3.0-7.5 L/min) by CMR and 4.7+/-1.1 L/min by CWD (2.5-8.0 L/min, P = .004), respectively. CWD measurements showed an acceptable agreement with CMR (bias: 0.6+/-1.1 L/min) and a high reproducibility (bias: 0.1+/-0.4 L/min). Higher CO and body mass index (BMI) were identified as sources of inaccuracy in univariate analysis. By multivariate analysis, only CO(CMR) was found to be independently associated with larger variation. Estimated diameters of the left ventricular outflow tract (LVOT), a prerequisite for CO measurement by CWD, correlated only weakly with those measured by CMR.

CONCLUSIONS

Continuous wave Doppler is a feasible technique for measuring cardiac function. Although the overall agreement with CMR was acceptable, CWD showed a trend to underestimate CO. The estimated LVOT diameter by CWD is likely to be an important source of error. Nevertheless, the CWD device could be of clinical use especially for detection of intraindividual hemodynamic changes since a high reproducibility could be demonstrated.

Right ventricular inefficiency in repaired tetralogy of Fallot: proof of concept for energy calculations from cardiac MRI data

Repaired tetralogy of Fallot (rTOF) patients develop right ventricular (RV) dilatation and dysfunction. To prevent their demise, pulmonary valve replacement is necessary, though appropriate timing for it is challenged by a paucity of reliable diagnostic parameters. In this pilot study, we hypothesized that stroke work (SW) and energy calculations would delineate the inefficiency of RV performance in rTOF. RV SW was calculated for both an rTOF and a normal subject by utilizing RV pressure and volume measurements obtained during cardiac catheterization and MRI studies. Energy transfer rate and ratio were computed at the main pulmonary artery (PA). Compared to the normal RV, the rTOF RV had higher operating pressure, lower computed SW (0.078 J vs. 0.115 J for normal), and higher negative energy transfer at the PA (0.044 J vs. 0.002 J for normal). Furthermore, the energy transfer ratio was nearly twice as high for the normal RV (1.06) as for the rTOF RV (0.56). RV SW and energy transfer ratio delineate important operational efficiency differences in blood flow from the RV to the PA between rTOF and normal subjects. Our pilot data suggest that the rTOF RV is significantly less efficient than normal.

Plasma levels of von Willebrand factor are increased in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterised by inappropriate hypertrophy, small-vessel coronary artery disease, myocyte disarray and increased interstitial fibrosis. Microvascular dysfunction is a common finding in HCM and its extent has been proposed as an important prognostic marker. Plasma von Willebrand factor (vWf) is an established marker of endothelial damage or dysfunction; however it has scarcely been studied in HCM. We hypothesised that vWf could be raised in patients with HCM and be related to different variables associated with severity of HCM.

METHODS

We included 124 HCM patients, 93 males, aged 48+/-15 years, 59 healthy control subjects with similar age and sex and 20 patients with ischemic heart disease but clinical stability for the last 6 months. A complete history and clinical examination was performed, including 12-lead electrocardiogram, echocardiography, 24 hours ECG-Holter monitoring, and symptom limited treadmill exercise test. Risk factors for sudden death were evaluated. A blinded cardiac MRI was performed with late enhanced study with Gadolinium. Plasma vWf levels were assayed by commercial ELISA.

RESULTS

Patients showed higher levels of vWf (140.0+/-65.0 UI/ml vs 105.0+/-51.0 UI/ml, p<0.001) even after adjusting for ABO blood group. vWf levels were found raised in patients with severe functional class (168.4+/-65.9 UI/mL vs 132.4+/-60.7 UI/mL, p=0.020), atrial fibrillation (175.8+/-69.4 UI/mL vs 133.0+/-59.0 UI/mL, p=0.005), hypertension (161.4+/-60.8 vs 128.9+/-60.5, p=0.010) obstruction (153.9+/-67.9 vs 128.2+/-57.4 UI/mL, p=0.046) and non sustained ventricular tachycardia (159.3+/-59.1 vs 133.0+/-63.0, p=0.049). vWf correlated with age (r:0.26; p=0.006) and obstruction (r:0.22; p=0.021).

CONCLUSIONS

We show, for the first time, patients with HCM present significantly raised levels of vWf. These are associated with different conditions related to the severity of the disease.

Noninvasive imaging of the heart and coronary arteries

There are multiple imaging modalities currently available to noninvasively evaluate the heart and coronary arteries. Choosing the most appropriate modality depends on the pertinent clinical question and the underlying patient characteristics. This article provides an overview of the fields of echocardiography, myocardial perfusion imaging, cardiac computed tomography, and cardiac magnetic resonance imaging, with particular attention to specific clinical applications for cardiac surgery patients.

Cardiac magnetic resonance versus transthoracic echocardiography for the assessment of cardiac volumes and regional function after myocardial infarction: an intrasubject comparison using simultaneous intrasubject recordings

Background

Although echocardiography is commonly used to evaluate cardiac function after MI, CMR may provide more accurate functional assessment but has not been adequately compared with echo. The primary study objective was to compare metrics of left ventricular volumes and global and regional function determined by cardiac magnetic resonance (CMR) and echocardiography (echo) in patients (pts) with recent myocardial infarction (MI).

Methods

To compare CMR with echo, 47 consecutive patients (pts 70% male; mean age = 66 ± 11 years) with MI >6 wks previously and scheduled for imaging evaluation were studied by both echo and CMR within 60 min of each other. Readers were blinded to pt information. Pearson's correlation coefficient, paired t-tests, and chi-square tests were used to compare CMR and echo measures. Further comparisons were made between pts and 30 normal controls for CMR and between pts and published normal ranges for echo.

Results

Measures of volume and function correlated moderately well between CMR and echo (r = 0.54 to 0.75, all p < 0.001), but large and systematic differences were noted in absolute measurements. Echo underestimated left ventricular (LV) volumes (by 69 ml for end-diastolic, 35 ml for end-systolic volume, both p < 0.001), stroke volume (by 34 ml, p < 0.001), and LV ejection fraction (LVEF) (by 4 percentage point, p = 0.02). CMR was much more sensitive to detection of segmental wall motion abnormalities (p < 0.001). CMR comparisons with normal controls confirmed an increase in LV volumes, a decrease in LVEF, and preservation of stroke volume after MI.

Conclusion

This intra subject comparison after MI found large, systematic differences between CMR and echo measures of volumes, LVEF, and wall motion abnormality despite moderate inter-modality correlations, with echo underestimating each metric. CMR also provided superior detection and quantification of segmental function after MI. Serial studies of LV function in individual patients should use the same modality.

Circumferential strain analysis identifies strata of cardiomyopathy in Duchenne muscular dystrophy: a cardiac magnetic resonance tagging study

OBJECTIVES

This study sought to evaluate the natural history of occult cardiac dysfunction in Duchenne muscular dystrophy (DMD).

BACKGROUND

Duchenne muscular dystrophy is characterized by progressive cardiac dysfunction and myocardial fibrosis late in the disease process. We hypothesized that left ventricular myocardial peak circumferential strain (epsilon(cc)) would decrease in DMD before global systolic functional abnormalities regardless of age or ventricular ejection fraction (EF).

METHODS

We evaluated cardiac magnetic resonance image (MRI) data from 70 DMD patients and 16 aged-matched control subjects. Standard imaging data included steady-state free precession short-axis cine stack images, cine myocardial tagged images, and myocardial delayed enhancement (MDE) (an indicator of myocardial fibrosis) sequences. Analysis was performed with QMASS (Medis Medical Imaging Systems, Leiden, the Netherlands) and HARP (Diagnosoft, Palo Alto, California) software. The DMD patient data were subdivided by age (<10 or >10 years), EF (>55% or <55%), and the presence or absence of MDE.

RESULTS

The DMD patients with normal EF had reduced epsilon(cc) at an early age (<10 years) compared with control subjects (p < 0.01). The DMD patients age >10 years with normal EF had further decline in epsilon(cc) compared with younger DMD patients (p < 0.01). There was further decline in epsilon(cc) with age in patients with reduced EF (p < 0.01) without MDE. The oldest patients, with both reduced EF and positive MDE, exhibited the lowest epsilon(cc). None of the patients had ventricular hypertrophy.

CONCLUSIONS

Myocardial strain abnormalities are prevalent in young DMD patients despite normal EF, and these strain values continue to decline with advancing age. Strain analysis in combination with standard MRI and MDE imaging provides a means to stratify DMD cardiomyopathy.

[Complication of a complex heart failure: perforation of a sinus Valsalva [corrected] aneurysm]

A 68-year-old woman was admitted to hospital because of chronic heart failure. The cause was a left-right shunt between the left sinus of Valsalva and the right atrium. The patient underwent surgery with shunt closure. Intraoperatively, the ramus circumflexus of the coronary artery was occluded. 2.5 years later the patient was readmitted to hospital. There was acute heart failure caused by an ischemic mitral regurgitation III degrees . A planned mitral valve replacement and operative myocardial revascularization were not performed because the patient developed a drug-induced hepatotoxic failure under phenprocoumon.

Inert gas rebreathing: the effect of haemoglobin based pulmonary shunt flow correction on the accuracy of cardiac output measurements in clinical practice

BACKGROUND

Cardiac output (CO) is an important cardiac parameter, however its determination is difficult in clinical routine. Non-invasive inert gas rebreathing (IGR) measurements yielded promising results in recent studies. It directly measures pulmonary blood flow (PBF) which equals CO in absence of significant pulmonary shunt flow (Q(S)). A reliable shunt correction requiring the haemoglobin concentration (c(Hb)) as only value to be entered manually has been implemented. Therefore, the aim of the study was to evaluate the effect of various approaches to Q(S) correction on the accuracy of IGR.

METHODS

Cardiac output determined by cardiac magnetic resonance imaging (CMR) served as reference values. The data was analysed in four groups: PBF without correcting for Q(S) (group A), shunt correction using the patients' individual c(Hb) values (group B), a fixed standard c(Hb) of 14.0 g dl(-1) (group C) and a gender-adapted standard c(Hb) for male (15.0 g dl(-1)) and female (13.5 g dl(-1)) probands each (group D).

RESULTS

147 patients were analysed. Mean CO(CMR) was 5.2 +/- 1.4 l min(-1), mean CO(IGR) was 4.8 +/- 1.3 l min(-1) in group A, 5.1 +/- 1.3 in group B, 5.1 +/- 1.3 l min(-1) in group C and 5.1 +/- 1.4 l min(-1) in group D. The accuracy in group A (mean bias 0.5 +/- 1.1 l min(-1)) was significantly lower as compared to groups B, C and D (0.1 +/- 1.1 l min(-1); P<0.01).

CONCLUSION

IGR allows a reliable non-invasive determination of CO. Since PBF significantly increased the measurement bias, shunt correction should always be applied. A fixed c(Hb) of 14.0 g dl(-1) can be used for both genders if the exact c(Hb) value is not known. Nevertheless, the individual value should be used if any possible.

Pathophysiology, diagnosis, and management of aortic dissection

Aortic dissection is an uncommon but potentially fatal disease with catastrophic complications. A high level of suspicion is required for successful diagnosis as presenting symptoms are so variable that dissection may be overlooked in up to 39% of cases. It most commonly presents in the elderly population with a history of chronic hypertension. Rapid intervention is necessary as delay leads to higher mortality. Despite advances in diagnostic and therapeutic techniques, morbidity and mortality remains high. Advances in diagnostic imaging have raised the awareness of variants of aortic dissection, including intramural hemorrhage and penetrating aortic ulcer. This distinction is important as the clinical course of these variants differs from that of classical aortic dissection, and thus treatment may also differ. Understanding of these variants has also led to the recognition of markers that may help predict progression to classical aortic dissection and thus warrant closer vigilance in selected patient populations. The recognition that rapid diagnosis is required for management of aortic dissection has led to the investigation of serum tests as diagnostic aids. Serum smooth muscle myosin heavy chain, d-dimer, and serum soluble elastin fragments are promising tests that may help raise suspicion for the diagnosis of acute aortic dissection. The high mortality associated with surgical therapy has led to investigation of alternative approaches. Endovascular therapy has emerged as a viable option in patients with type B dissection who are too unstable for surgery. However, long-term follow up is required to validate this procedure.

Descending Thoracic Aortic Dissection: Evaluation and Management in the Era of Endovascular Technology

Acute aortic dissection is a relatively uncommon but highly lethal condition. Without proper treatment, devastating consequences can occur due to aortic rupture, cardiac tamponade, or irreversible ischemia involving the spinal cord or the visceral organs. The treatment strategy of this condition is in part influenced by the location and the severity of aortic dissection as immediate surgical intervention is necessary in acute ascending aortic dissection, whereas medical therapy is the initial treatment approach in uncomplicated descending aortic dissection. Recent advances of endovascular technology have broadened the potential application of this catheter-based therapy in aortic pathologies, including descending thoracic aortic dissection. In this article, the etiology, pathogenesis, and classification of this condition are discussed. The diagnostic benefits of various imaging modalities for descending aortic dissection are also discussed. Current treatment strategies, including medical, surgical, and catheter-based interventions, are reviewed. Lastly, clinical experiences of endovascular treatment for descending aortic dissection and various endovascular devices potentially applicable for this condition are discussed.

Cardiovascular response to acute hypoxemia induced by prolonged breath holding in air

Prolonged breath hold (BH) represents a valid model for studying the cardiac adaptation to acute hypoxemia in humans. Cardiac magnetic resonance (CMR) allows a three-dimensional, high-resolution, noninvasive, and nonionizing anatomical and functional evaluation of the heart. The aim of the study was to assess the adaptation of the cardiovascular system to prolonged BH in air. Ten male volunteer diving athletes (age 30 +/- 6 yr) were studied during maximal BH duration with CMR. Four epochs were studied: I, rest; II and III, intermediate BH; and IV, peak BH. Oxygen saturation (So(2)), heart rate (HR), blood pressure (BP), systemic vascular resistance (VR), end-diastolic (EDV) and end-systolic volumes (ESV), stroke volume (SV), cardiac output (CO), ejection fraction (EF), maximal elastance index (EL), systolic wall thickening (SWT), and end-systolic wall stress (ESWS) of the left ventricle (LV) were measured in all four BH epochs. Average BH duration was 3.7 +/- 0.3 min. So(2) was reduced (I: 97 +/- 0.2%, range 96-98%, vs. IV: 84 +/- 2.0%, range 76-92%; P < 0.00001). BP, EDV, ESV, SV, CO, and ESWS linearly increased from epochs I to IV, whereas EF, EL, and SWT showed an opposite behavior, decreasing from resting to epoch IV (all trends are P < 0.01). During prolonged BH in air, a marked enlargement of the LV chamber occurs in healthy diving athletes. This response to acute hypoxemia allows SV,CO, and arterial pressure to be maintained despite the severe reduction in LV contractile function.

Traditional cardiovascular risk factors in relation to left ventricular mass, volume, and systolic function by cardiac magnetic resonance imaging: the Multiethnic Study of Atherosclerosis

OBJECTIVES

The goal of this study was to examine the cross-sectional associations of cardiovascular risk factors with left ventricular (LV) geometry and systolic function measured by cardiac magnetic resonance imaging (MRI) in the Multiethnic Study of Atherosclerosis (MESA).

BACKGROUND

Cardiovascular risk factors including hypertension, smoking, and obesity are known to be associated with increased LV mass, but less is known about the association of risk factors with LV systolic function, particularly in populations without clinical cardiovascular disease.

METHODS

Participants were from 4 racial/ethnic groups and were free of clinical cardiovascular disease. Blood pressure, health habits, body mass index, lipid levels, and glucose abnormalities were assessed and MRI exams performed at baseline (n = 4,869). Multivariable linear regression was used to model the association of risk factors with LV mass, end-diastolic volume, stroke volume, ejection fraction, and cardiac output.

RESULTS

The mean age was 62 years, and 52% of the participants were women. After adjustment for sociodemographic variables and height, higher systolic blood pressure and body mass index were associated with larger LV mass and volumes. Current smoking and diabetes were associated with greater LV mass (+7.7 g, 95% confidence interval [CI] +5.5 to +9.9 and +3.5 g, 95% CI +1.2 to +5.8, respectively), and with lower stroke volume (-1.9 ml, 95% CI -3.3 to -0.5 and -4.5 ml, 95% CI -6.0 to -3.0, respectively) and lower ejection fraction (-1.6%, 95% CI -2.1 to -1.0 and -0.8%, 95% CI -1.5 to -0.2, respectively).

CONCLUSIONS

In this cohort free of clinical cardiovascular disease, modifiable risk factors were associated with subclinical alterations in LV size and systolic function as detected by cardiac MRI.

Constrictive pericarditis: A reminder of a not so rare disease

Constrictive pericarditis is a rare condition characterized by clinical signs of right heart failure subsequent to loss of pericardial compliance. The etiology of constrictive pericarditis has changed during the last decades in developed countries. While, in the past, tuberculosis and idiopathic pericardial constriction were the prevalent causes of the disease, cardiac surgery has become one of the main reasons for its development in recent years. However, cases defined as idiopathic constrictive pericarditis are still observed. In addition to the classical chronic and subacute forms, new presentations, such as effusive-constrictive, localized, transient, occult, and constrictive pericarditis with normal pericardial thickness, have been described. Although conservative treatment may alleviate the patient's symptoms, pericardiectomy remains the only definitive treatment for the disease. It is worth noting that the sooner the diagnosis of pericardial constriction is established, the better the outcome is. The pathophysiological features, clinical findings, diagnostic tools, and therapeutic approach to constrictive pericarditis are detailed in this review.

Analysis of the extension of Q-waves after infarction with body surface map: Relationship with infarct size

AIMS

We aimed to characterize the extension of Q-waves after a first ST-segment elevation myocardial infarction using body surface map (BSM) and its relationship with infarct size quantified with cardiovascular magnetic resonance imaging (CMR).

METHODS AND RESULTS

Thirty-five patients were studied 6 months after a first ST-segment elevation myocardial infarction (23 anterior, 12 inferior). All cases had single-vessel disease and an open artery. The extension of Q-waves was analyzed by means of a 64-lead BSM. Infarct size was quantified with CMR. Absence of Q-waves in BSM was observed in 5 patients (14%), 2 of whom (40%) had >1 segment with transmural necrosis. Absence of Q-waves in 12-lead ECG was observed in 8 patients (23%), 7 of whom (87%) had >1 segment with transmural necrosis. Patients with inferior infarctions (n=12, 34%) showed a larger number of Q-waves in BSM (18+/-7.1 leads) than patients with anterior infarctions (n=23, 66%; 3.7+/-3.6 leads; p<0.0001). When the study group was analysed as a whole, the total number of Q-waves detected in BSM did not correlate with the number of necrotic segments (r=0.15; p=0.4). In anterior infarctions, a number of Q-waves >median (2 leads) was related to a higher number of necrotic segments (5.1+/-2.4 vs. 2+/-2.2 segments; p=0.004). The same was observed in inferior infarctions (median 20 leads: 3.5+/-1.9 vs. 1.2+/-1.2 segments; p=0.03).

CONCLUSION

In a stable phase after a first ST-segment elevation myocardial infarction, absence of Q-waves does not mean non-transmural necrosis. Using BSM, extension of Q-waves is much higher in inferior infarctions; a separate analysis depending on infarct location is necessary. A major BSM-derived extension of Q-waves is related to larger infarct size both in anterior and in inferior infarctions.

Parallel imaging in cardiovascular MRI: methods and applications

Cardiovascular MR imaging (CVMR) has become a valuable modality for the non-invasive detection and characterization of cardiovascular diseases. CVMR requires high imaging speed and efficiency, which is fundamentally limited in conventional cardiovascular MRI studies. With the introduction of parallel imaging, alternative means for increasing acquisition speed beyond these limits have become available. In parallel imaging some image data are acquired simultaneously, using RF detector coil sensitivities to encode simultaneous spatial information that complements the information gleaned from sequential application of magnetic field gradients. The resulting improvements in imaging speed can be used in various ways, including shortening long examinations, improving spatial resolution and/or anatomic coverage, improving temporal resolution, enhancing image quality, overcoming physiological constraints, detecting and correcting for physiologic motion, and streamlining work flow. Examples of each of these strategies will be provided in this review. First, basic principles and key concepts of parallel MR are described. Second, practical considerations such as coil array design, coil sensitivity calibrations, customized pulse sequences and tailored imaging parameters are outlined. Next, cardiovascular applications of parallel MR are reviewed, ranging from cardiac anatomical and functional assessment to myocardial perfusion and viability to MR angiography of the coronary arteries and the large vessels. Finally, current trends and future directions in parallel CVMR are considered.