Late Enhancement Technique Research Articles

Early impairment of myocardial deformation assessed by regional speckle-tracking echocardiography in the indeterminate form of Chagas disease without fibrosis detected by cardiac magnetic resonance.

Chagas disease (CD) will account for 200,000 cardiovascular deaths worldwide over the next 5 years. Early detection of chronic Chagas cardiomyopathy (CCC) is a challenge. We aimed to test if speckle-tracking echocardiography (STE) can detect incipient myocardial damage in CD. METHODS: Among 325 individuals with positive serological tests, 25 (age 55±12yrs) were selected to compose the group with indeterminate form of Chagas disease (IFCD), based on stringent criteria of being asymptomatic and with normal EKG/X-ray studies. This group was compared with a group of 20 patients with CCC (55±11yrs) and a group of 20 non-infected matched control (NC) subjects (48±10yrs). CD patients and NC were submitted to STE and CD patients were submitted to cardiac magnetic resonance (CMR) with late gadolinium administration to detect cardiac fibrosis by the late enhancement technique. Global longitudinal strain (GLS), circumferential (GCS) and radial strain (GRS) were defined as the average of segments measured from three apical view (GLS) and short axis views (GRS and GCS). Regional left ventricular (LV) longitudinal strain (Reg LS) was measured from each of the 17 segments. Twist was measured as systolic peak difference between basal and apical rotation and indexed to LV length to express torsion. RESULTS: STE global indices (GLS, GCS, twist and torsion) were reduced in CCC vs NC (GLS: -14±6.3% vs -19.3±1.6%, p = 0.001; GCS: -13.6±5.2% vs -17.3 ±2.8%; p = 0.008; twist: 8±7° vs 14±7°, p = 0.01 and torsion: 0.96±1°/cm vs 1.9±1°/cm, p = 0.005), but showed no differences in IFCD vs NC. RegLS was reduced in IFCD vs NC in four LV segments: basal-inferior (-16.3±3.3% vs -18.6±2.2%, p = 0.013), basal inferoseptal (-13.1±3.4 vs -15.2±2.7, p = 0.019), mid-inferoseptal (-17.7±3.2 vs -19.4±2, p = 0.032) and mid-inferolateral (-15.2±3.5 vs -17.8±2.8, p = 0.014). These abnormalities in RegLS occurred in the absence of myocardial fibrosis detectable with CMR in nearly 92% of subjects with IFCD, while myocardial fibrosis was present in 65% with CCC. CONCLUSION: RegLS detects early regional impairment of myocardial strain that is independent from fibrosis in IFCD subjects.

Parametric techniques for characterizing myocardial tissue through magnetic resonance imaging (Part 1): T1 mapping

The development of myocardial fibrosis is a common process in the appearance of ventricular dysfunction in many heart diseases. Magnetic resonance imaging makes it possible to accurately evaluate the structure and function of the heart, and its role in the macroscopic characterization of myocardial fibrosis by late enhancement techniques has been widely validated clinically. Recent studies have demonstrated that T1-mapping techniques can quantify diffuse myocardial fibrosis and the expansion of the myocardial extracellular space in absolute terms. However, further studies are necessary to validate the usefulness of this technique in the early detection of tissue remodeling at a time when implementing early treatment would improve a patient's prognosis. This article reviews the state of the art for T1 mapping of the myocardium, its clinical applications, and its limitations.

Técnicas paramétricas de caracterización tisular del miocardio mediante resonancia magnética (parte 1): mapas de T1

The development of myocardial fibrosis is a common process in the appearance of ventricular dysfunction in many heart diseases. Magnetic resonance imaging makes it possible to accurately evaluate the structure and function of the heart, and its role in the macroscopic characterization of myocardial fibrosis by late enhancement techniques has been widely validated clinically. Recent studies have demonstrated that T1-mapping techniques can quantify diffuse myocardial fibrosis and the expansion of the myocardial extracellular space in absolute terms. However, further studies are necessary to validate the usefulness of this technique in the early detection of tissue remodeling at a time when implementing early treatment would improve a patient's prognosis. This article reviews the state of the art for T1 mapping of the myocardium, its clinical applications, and its limitations.

Left Ventricular Geometry and Blood Pressure as Predictors of Adverse Progression of Fabry Cardiomyopathy.

BackgroundIn spite of several research studies help to describe the heart in Fabry disease (FD), the cardiomyopathy is not entirely understood. In addition, the impact of blood pressure and alterations in geometry have not been systematically evaluated.MethodsIn 74 FD patients (mean age 36±12 years; 45 females) the extent of myocardial fibrosis and its progression were quantified using cardiac magnetic-resonance-imaging with late enhancement technique (LE). Results were compared to standard echocardiography complemented by 2D-speckle-tracking, 3D-sphericity-index (SI) and standardized blood pressure measurement. At baseline, no patient received enzyme replacement therapy (ERT). After 51±24 months, a follow-up examination was performed.ResultsSystolic blood pressure (SBP) was higher in patients with vs. without LE: 123±17 mmHg vs. 115±13 mmHg; P = 0.04. A positive correlation was found between SI and the amount of LE-positive myocardium (r = 0.51; P<0.001) indicating an association of higher SI in more advanced stages of the cardiomyopathy. SI at baseline was positively associated with the increase of LE-positive myocardium during follow-up. The highest SBP (125±19 mmHg) and also the highest SI (0.32±0.05) was found in the subgroup with a rapidly increasing LE (ie, ≥0.2% per year; n = 16; P = 0.04). Multivariate logistic regression analysis including SI, SBP, EF, left ventricular volumes, wall thickness and NT-proBNP adjusted for age and sex showed SI as the most powerful parameter to detect rapid progression of LE (AUC = 0.785; P<0.05).ConclusionsLV geometry as assessed by the sphericity index is altered in relation to the stage of the Fabry cardiomyopathy. Although patients with FD are not hypertensive, the SBP has a clear impact on the progression of the cardiomyopathy.

Relation of the ischaemic substrate to left ventricular remodelling by cardiac magnetic resonance at 1.5 T in rabbits

Contrast-enhanced cardiac magnetic resonance (CMR) for infarct sizing has been validated in large animals, but studies and follow-up are restricted. We sought to (1) validate CMR for assessment of myocardial area at risk (MAR) and infarct size (IS) in a rabbit model of reperfused myocardial infarction (MI); (2) analyse the relation between ischaemic substrates and subsequent left ventricular (LV) remodelling. Experimental reperfused acute MI was induced in 16 rabbits. Ten animals underwent cross-registered cine and contrast-enhanced CMR and histopathology at day 3 for assessment of MAR and IS (group 1). The remaining six rabbits underwent serial CMR for the study of LV remodelling (group 2). In group 1, mean IS was 12.7 +/- 6.4% and 12.7 +/- 6.9% of total LV myocardial mass on CMR (late-enhancement technique) and histopathology (P = 0.52; r = 0.93). No significant difference occurred between CMR and histopathology for the calculation of MAR and IS/MAR ratio (P = 0.18 and P = 0.17), whereas correlations were strong (r = 0.92 and r = 0.95). In group 2, mean LV end-diastolic, end-systolic volumes and LV mass were significantly increased at 3 weeks compared with measurements at day 3 (P < 0.01). Significant correlations between initial IS and the increase in LV end-diastolic volume (r = 0.66) and the increase in LV mass (r = 0.48) were observed, as well as correlations between initial MAR and the increase in LV end-diastolic volume (r = 0.70) and the increase in LV mass (r = 0.37). Comprehensive CMR provides accurate assessment of IS and MAR in reperfused rabbit MI. Infarct size is closely related to LV remodelling. Through the infarct size/MAR ratio, this approach has great potential for assessing interventions aimed at cardioprotection.

Long-Term Effects of Enzyme Replacement Therapy on Fabry Cardiomyopathy

Enzyme replacement therapy with recombinant alpha-galactosidase A reduces left ventricular hypertrophy and improves regional myocardial function in patients with Fabry disease during short-term treatment. Whether enzyme replacement therapy is effective in all stages of Fabry cardiomyopathy during long-term follow-up is unknown. We studied 32 Fabry patients over a period of 3 years regarding disease progression and clinical outcome under enzyme replacement therapy. Regional myocardial fibrosis was assessed by magnetic resonance imaging late-enhancement technique. Echocardiographic myocardial mass was calculated with the Devereux formula, and myocardial function was quantified by ultrasonic strain-rate imaging. In addition, exercise capacity was measured by bicycle stress test. All measurements were repeated at yearly intervals. At baseline, 9 patients demonstrated at least 2 fibrotic left ventricular segments (severe myocardial fibrosis), 11 had 1 left ventricular segment affected (mild fibrosis), and 12 were without fibrosis. In patients without fibrosis, enzyme replacement therapy resulted in a significant reduction in left ventricular mass (238+/-42 g at baseline, 202+/-46 g at 3 years; P for trend <0.001), an improvement in myocardial function (systolic radial strain rate, 2.3+/-0.4 and 2.9+/-0.6 seconds(-1), respectively; P for trend=0.045), and a higher exercise capacity obtained by bicycle stress exercise (106+/-14 and 122+/-26 W, respectively; P for trend=0.014). In contrast, patients with mild or severe fibrosis showed a minor reduction in left ventricular hypertrophy and no improvement in myocardial function or exercise capacity. These data suggest that treatment of Fabry cardiomyopathy with recombinant alpha-galactosidase A should best be started before myocardial fibrosis has developed to achieve long-term improvement in myocardial morphology and function and exercise capacity.

The post–myocardial infarction scarred ventricle and congestive heart failure: The preeminence of magnetic resonance imaging for preoperative, intraoperative, and postoperative assessment

Magnetic resonance imaging (MRI), with its ability to precisely define myocardial anatomy, echoes the teachings of one of cardiac surgery’s most distinguished pioneers. Since the 1990s, several studies have demonstrated the preeminence of cardiac magnetic resonance (CMR) for analysis of wall motion abnormalities after myocardial infarction (MI). Both cine-MRI to determine precise scar location and the late enhancement technique to assess the transmural extension of infarcted myocardium illustrate the utility of CMR. CMR is the preeminent method of assessing left ventricular remodeling and aneurysmal progression after MI. Moreover, thrombus formation; the site, depth, and extension of the scarred myocardial wall; precise localization of asynergic areas; disorganization of the mitral apparatus; and estimation of left ventricular volume and performance are all circumstances in which CMR has proved more accurate than other techniques. In our opinion, a complete MRI evaluation of cardiac function is paramount before deciding how to appropriately treat patients after MI. The core problem with ischemic congestive heart failure (CHF) is the undue demand put on the residual viable left ventricular myocardium. As noted by Klein and colleagues more than 40 years ago, ‘‘When the myocardium in the aneurismal area functions improperly, or has been replaced by fibrosis in 20%–25% of the surface area of the left ventricle, the extent of shortening required of the remaining functioning heart begins to exceed physiological limits.’’ This was later confirmed by McKay and associates, who showed that left ventricular dilatation occurs when the asynergic (dyskinetic or akinetic) left ventricular circumference exceeds 40%.

1016 Increased sensitivity for detection of intra-cardiac thrombus using phase sensitive inversion recovery (PSIR) late enhancement techniques for combined myocardial scar and thrombus imaging

1016 Increased sensitivity for detection of intra-cardiac thrombus using phase sensitive inversion recovery (PSIR) late enhancement techniques for combined myocardial scar and thrombus imaging

Late contrast enhancement by CMR: more than scar?

Late contrast enhancement by CMR: more than scar?

Indications de l’IRM dans la maladie coronaire

Magnetic resonance imaging (MRI) has become a useful, even essential, examination in recent years, for the exploration of patients with coronary disease. MRI has several different roles, even though it remains insufficiently requested because insufficiently available. Today it is the reference examination for assessing indicators of ventricular function (volume, ejection fraction, ventricular mass); their prognostic value and importance in determining treatment are well recognized. In the postinfarction period, MRI using late enhancement techniques allows a precise analysis of the extent of necrosis, in terms of segments and transmural involvement. MRI is indicated, especially preoperatively, in cases of ventricular remodeling and its consequences (functional impairment, aneurysms, parietal thrombus). MRI with pharmacological stress may also be used as a tool for detecting myocardial ischemia; in this case, perfusion or first-pass sequences should be used. On the other hand, cardiac MRI for morphologic exploration of the coronary network and measurement of stenosis is not yet routine.

Limited Flow Reserve in Non-Obstructed Bypass Grafts Supplying Infarcted Myocardium: Implications for Cardiovascular Magnetic Resonance Imaging Protocols

We evaluated flow reserve in non-obstructed bypass grafts supplying infarcted and noninfarcted myocardium. Bypass grafts were examined by phase-contrast flow measurements and myocardial viability was assessed with late enhancement technique. Flow reserve was higher in bypasses supplying normal myocardium compared to those supplying infarcted myocardium (2.9 vs. 1.5, p<.0001). This difference remained significant after adjusting for co-variables. Bypass grafts supplying infarcted myocardium were more likely to have lower flow reserve than those supplying normal myocardium (flow reserve < or =2, 84% vs 18%, p = .0003). Flow reserve is reduced in non-stenosed bypasses supplying infarcted myocardium, likely due to altered microcirculation. Thus, cardiovascular magnetic resonance based bypass assessment must include myocardial viability testing.