Mechanical Dispersion Assessed by Myocardial Strain in Patients After Myocardial Infarction for Risk Prediction of Ventricular Arrhythmia

ObjectivesThe aim of this study was to investigate whether myocardial strain echocardiography can predict ventricular arrhythmias in patients after myocardial infarction (MI).BackgroundLeft ventricular (LV) ejection fraction (EF) is insufficient for selecting patients for implantable cardioverter-defibrillator (ICD) therapy after MI. Electrical dispersion in infarcted myocardium facilitates malignant arrhythmia. Myocardial strain by echocardiography can quantify detailed regional and global myocardial function and timing. We hypothesized that electrical abnormalities in patients after MI will lead to LV mechanical dispersion, which can be measured as regional heterogeneity of contraction by myocardial strain.MethodsWe prospectively included 85 post-MI patients, 44 meeting primary and 41 meeting secondary ICD prevention criteria. After 2.3 years (range 0.6 to 5.5 years) of follow-up, 47 patients had no and 38 patients had 1 or more recorded arrhythmias requiring appropriate ICD therapy. Longitudinal strain was measured by speckle tracking echocardiography. The SD of time to maximum myocardial shortening in a 16-segment LV model was calculated as a parameter of mechanical dispersion. Global strain was calculated as average strain in a 16-segment LV model.ResultsThe EF did not differ between ICD patients with and without arrhythmias occurring during follow-up (34 ± 11% vs. 35 ± 9%, p = 0.70). Mechanical dispersion was greater in ICD patients with recorded ventricular arrhythmias compared with those without (85 ± 29 ms vs. 56 ± 13 ms, p < 0.001). By Cox regression, mechanical dispersion was a strong and independent predictor of arrhythmias requiring ICD therapy (hazard ratio: 1.25 per 10-ms increase, 95% confidence interval: 1.1 to 1.4, p < 0.001). In patients with an EF >35%, global strain showed better LV function in those without recorded arrhythmias (−14.0% ± 4.0% vs. −12.0 ± 3.0%, p = 0.05), whereas the EF did not differ (44 ± 8% vs. 41 ± 5%, p = 0.23).ConclusionsMechanical dispersion was more pronounced in post-MI patients with recurrent arrhythmias. Global strain was a marker of arrhythmias in post-MI patients with relatively preserved ventricular function. These novel parameters assessed by myocardial strain may add important information about susceptibility for ventricular arrhythmias after MI

Modified Continuity Equation Using Left Ventricular Outflow Tract Three-Dimensional Imaging for Aortic Valve Area Estimation

PURPOSE: Aortic valve area (AVA) is usually estimated by the continuity equation (CE) in which the left ventricular outflow tract (LVOT) area is calculated assuming a circular shape. This study aimed to compare measurements of LVOT area using standard 2D transthoracic echocardiography (2DTTE), 3D transesophageal echocardiography (3DTEE), and multidetector computed tomography (MDCT) and assess their relative impact on AVA estimated by the CE. METHODS AND RESULTS: We prospectively enrolled 60 patients with severe aortic stenosis (AS) referred for transcatheter aortic valve replacement (TAVR) who systematically underwent 2DTTE, 3DTEE, and MDCT. Mean LVOT areas obtained by 2DTTE (3.28±0.66 cm2 ) and 3DTEE (3.95±0.90 cm2 ) were significantly underestimated when compared to the mean MDCT LVOT area (4.31±0.99 cm2 ). LVOT was rather elliptical than round, with a mean eccentricity index of 1.47 (ratio of maximum to minimum LVOT diameters) assessed by MDCT. Mean TTE AVA estimated by the CE was 0.62±0.20 cm2 . Substitution of 2DTTE LVOT area by 3DTEE LVOT area in the CE resulted in AVA of 0.74±0.24 cm2 , while using MDCT LVOT area held an AVA of 0.80±0.24 cm2 . MDCT-derived AVA was similar to MDCT planimetric AVA and allowed 24% of patients to be reclassified from severe to moderate AS. CONCLUSIONS: 2DTTE and 3DTEE underestimate LVOT area when compared to MDCT with significant impact on AVA estimation. Assessment through MDCT fusion AVA may be of incremental value in patients with discrepant severity criteria for AS.info:eu-repo/semantics/publishedVersio

Flow propagation velocity is not a simple index of diastolic function in early filling. A comparative study of early diastolic strain rate and strain rate propagation, flow and flow propagation in normal and reduced diastolic function

BACKGROUND: Strain Rate Imaging shows the filling phases of the left ventricle to consist of a wave of myocardial stretching, propagating from base to apex. The propagation velocity of the strain rate wave is reduced in delayed relaxation. This study examined the relation between the propagation velocity of strain rate in the myocardium and the propagation velocity of flow during early filling. METHODS: 12 normal subjects and 13 patients with treated hypertension and normal systolic function were studied. Patients and controls differed significantly in diastolic early mitral flow measurements, peak early diastolic tissue velocity and peak early diastolic strain rate, showing delayed relaxation in the patient group. There were no significant differences in EF or diastolic diameter. RESULTS: Strain rate propagation velocity was reduced in the patient group while flow propagation velocity was increased. There was a negative correlation (R = -0.57) between strain rate propagation and deceleration time of the mitral flow E-wave (R = -0.51) and between strain rate propagation and flow propagation velocity and there was a positive correlation (R = 0.67) between the ratio between peak mitral flow velocity / strain rate propagation velocity and flow propagation velocity. CONCLUSION: The present study shows strain rate propagation to be a measure of filling time, but flow propagation to be a function of both flow velocity and strain rate propagation. Thus flow propagation is not a simple index of diastolic function in delayed relaxation

A comparison of echocardiographic and electron beam computed tomographic assessment of aortic valve area in patients with valvular aortic stenosis

The purpose of this study was to compare electron beam computed tomography (EBT) with transthoracic echocardiography (TTE) in determining aortic valve area (AVA). Thirty patients (9 females, 21 males) underwent a contrast-enhanced EBT scan (e-Speed, GE, San Francisco, CA, USA) and TTE within 17 ± 12 days. In end-inspiratory breath hold, a prospectively ecg-triggered scan was acquired with a beam speed of 50–100 ms, a collimation of 2 × 1.5 mm and an increment of 3.0 mm. The AVA was measured with planimetry. A complete TTE study was performed in all patients, and the AVA was computed using the continuity equation. There was close correlation between AVA measured with EBT and AVA assessed with TTE (r = 0.60, P < 0.01). The AVA measured with EBT was 0.51 ± 0.46 cm2 larger than the AVA calculated with TTE measurements. EBT appeared to be a valuable non-invasive method to measure the AVA. EBT measures the anatomical AVA, while with TTE the functional AVA is calculated, which explains the difference in results between the methods

Androgen receptor gene polymorphism and the metabolic syndrome in 60-80 years old Norwegian men

The metabolic syndrome (MS) includes a clustering of metabolic derangements. Low testosterone levels have been shown to be associated with both components of MS and MS per se. As most androgen-related effects are mediated thorough the androgen receptor (AR), we wanted to investigate to which degree the AR CAG and GGN repeat polymorphisms might be related to MS. Sixty-eight men, 60-80 years old, with subnormal total testosterone levels ( 11.0 nmol/L), participating in a nested case-control study were investigated in this study. Body weight, height, waist circumferences and blood pressure were measured. Fasting blood samples were drawn and an oral glucose tolerance test (OGTT) was performed. The CAG and GGN polymorphisms in the AR gene were determined by direct sequencing of leucocyte DNA. Men with MS had lower CAG repeat number than healthy men (p = 0.007). There were, however, no difference in CAG or GGN repeats length between the groups with subnormal or normal testosterone concentrations. In cross-sectional analyses, men with CAG repeat lengths < 21 had significantly higher fasting glucose, C-peptide and glycosylated haemoglobin (HbA1c) levels (all p < 0.05). In multiple regression analyses, CAG repeat length was an inverse and independent predictor of glucose after an OGTT and of HbA1c levels. We also found that men with more than one component of MS had shorter CAG repeat number (p for trend 0.013) than those with only one component. In conclusion, there were no associations with GGN repeat length, while short CAG repeat length seems to be associated with increased risk of MS

Androgen receptor gene polymorphism and sex hormones in elderly men: the Tromso study

The aim of this study was to examine whether CAG/GGN repeats are significant modulators of serum concentrations of total and free testosterone (T) as well as of luteinizing hormone (LH) in elderly men. Sixty-nine 60- to 80-year-old men with subnormal T levels (<= 11.0 nmol L-1) and 104 men with normal T levels taking part in a nested case-control study were used for these analyses. Sex hormones were measured and free T was calculated. The CAG and GGN polymorphisms in the androgen receptor gene were determined by polymerase chain reaction and subsequent direct sequencing. There were no differences in the CAG and GGN repeat lengths between the groups. In cross-sectional analyses of the whole cohort, total and free T were positively associated with CAG length (all P < 0.05) before, but not after, waist circumference or body mass index was added to the model. CAG repeat lengths were weakly, but not independently, associated with total and free T. These findings indicate that when clinically evaluating T and LH levels in elderly men, the CAG and GGN repeat lengths do not need to be taken into consideration

Impact of global left ventricular afterload on left ventricular function in asymptomatic severe aortic stenosis: a two-dimensional speckle-tracking study.

Aims: The present study sought to assess the effect of global left ventricular (LV) afterload on LV myocardial systolic function in patients with aortic stenosis (AS) and preserved LV ejection fraction. Methods and results: We prospectively examined the LV myocardial deformation (i.e. longitudinal, radial, and circumferential) by two-dimensional speckle tracking in 173 patients with asymptomatic severe AS. Thirty-eight patients (22%) had lowflow as determined by a low stroke volume index (35 mL/m2). By multivariable analysis, four variables emerged as independently associated with low-flow AS: peak Ea velocity (P 1⁄4 0.01), left atrial area index (P 1⁄4 0.017), global LV afterload (P 1⁄4 0.024), and circumferential myocardial deformation (P 1⁄4 0.04). Forty-nine patients (28%) had an increased global LV afterload (5 mmHg mL/m2). Systemic arterial compliance (P 1⁄4 0.001), circumferential myocardial deformation (P 1⁄4 0.024), and left atrial area index (P 1⁄4 0.04) were independently associated with increased global LV load in multivariable analysis. Conclusion: In asymptomatic patients with severe AS, LV ejection fraction markedly underestimates the extent of myocardial sys- tolic impairment. Intrinsic myocardial dysfunction is particularly common in patients with increased global LV after- load, and especially in the subset of patients with low-flow AS