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

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

Design and baseline characteristics of the simvastatin and ezetimibe in aortic stenosis (SEAS) study

Aortic valve stenosis and, atherosclerotic disease have several risk factors in common, in particular, hypercholesterolemia. Histologically, the diseased valves appear to have areas of inflammation much like atherosclerotic plaques. The effect of lipid-lowering therapy on the progression of aortic stenosis (AS) is unclear, and there are no randomized treatment trials evaluating cardiovascular morbidity and mortality in such patients. The Sinivastatin and Ezetimibe in Aortic Stenosis (SEAS) Study is a randomized, double-blind, placebo-controlled, multicenter study of a minimum 4 years' duration investigating the effect of lipid lowering with ezetimibe/simvastatin 10/40 mg/day in patients with asymptomatic AS with peak transvalvular jet velocity 2.5 to 4.0 m/s. Primary efficacy variables include aortic valve surgery and ischemic vascular events, including cardiovascular mortality, and second, the effect on echocardiographically evaluated progression of AS. The SEAS Study randomly assigned 1,873 patients (age 68 +/- 10 years, 39% women, mean transaortic maximum velocity 3.1 +/- 0.5 m/s) from 173 sites. Other baseline characteristics were mean blood pressure of 145 +/- 20/82 +/- 10 mm Hg (51% hypertensive); 55% were current or previous smokers; and most were overweight (mean body mass index 26.9 kg/m(2)). At baseline, mean total cholesterol was 5.7 +/- 1.0 mmol/L (222 mg/dl), low-density lipoprotein cholesterol was 3.6 +/- 0.9 mmol/L (139 mg/dl), high-density lipoprotein cholesterol was 1.5 +/- 0.4 mmol/L (58 mg/dl), and triglycerides were 1.4 +/- 0.7 mmol/L (126 mg/dl). The SEAS Study is the largest randomized trial to date in patients with AS and will allow determination of the prognostic value of aggressive lipid lowering in such patients. (c) 2007 Elsevier Inc. All rights reserved

Impact of Baseline Severity of Aortic Valve Stenosis on Effect of Intensive Lipid Lowering Therapy (from the SEAS Study)

Retrospective studies have suggested a beneficial effect of lipid-lowering treatment on the progression of aortic stenosis (AS) in milder stages of the disease. In the randomized, placebo-controlled Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study, 4.3 years of combined treatment with simvastatin 40 mg and ezetimibe 10 mg did not reduce aortic valve events (AVEs), while ischemic cardiovascular events (ICEs) were significantly reduced in the overall study population. However, the impact of baseline AS severity on treatment effect has not been reported. Baseline and outcomes data in 1,763 SEAS patients (mean age 67 years, 39% women) were used. The study population was divided into tertiles of baseline peak aortic jet velocity (tertile 1: 2.8 to 3.3 m/s; tertile 3: >3.3 m/s). Treatment effect and interaction were tested in Cox regression analyses. The rates of AVEs and ICEs increased with increasing baseline severity of AS. In Cox regression analyses, higher baseline peak aortic jet velocity predicted higher rates of AVEs and ICEs in all tertiles (all p values <0.05) and in the total study population (p <0.001). Simvastatin-ezetimibe treatment was not associated with a statistically significant reduction in AVEs in any individual tertile. A significant quantitative interaction between the severity of AS and simvastatin-ezetimibe treatment effect was demonstrated for ICEs (p <0.05) but not for AVEs (p = 0.10). In conclusion, the SEAS study results demonstrate a strong relation between baseline the severity of AS and the rate of cardiovascular events but no significant effect of lipid-lowering treatment on AVEs, even in the group with the mildest AS. (C) 2010 Published by Elsevier Inc. (Am J Cardiol 2010;106:1634-1639

Intensive lipid lowering with simvastatin and ezetimibe in aortic stenosis

Background: Hyperlipidemia has been suggested as a risk factor for stenosis of the aortic valve, but lipid-lowering studies have had conflicting results. Methods: We conducted a randomized, double-blind trial involving 1873 patients with mild-to-moderate, asymptomatic aortic stenosis. The patients received either 40 mg of simvastatin plus 10 mg of ezetimibe or placebo daily. The primary outcome was a composite of major cardiovascular events, including death from cardiovascular causes, aortic-valve replacement, nonfatal myocardial infarction, hospitalization for unstable angina pectoris, heart failure, coronary-artery bypass grafting, percutaneous coronary intervention, and nonhemorrhagic stroke. Secondary outcomes were events related to aortic-valve stenosis and ischemic cardiovascular events. Results: During a median follow-up of 52.2 months, the primary outcome occurred in 333 patients (35.3%) in the simvastatin-ezetimibe group and in 355 patients (38.2%) in the placebo group (hazard ratio in the simvastatin-ezetimibe group, 0.96; 95% confidence interval [CI], 0.83 to 1.12; P=0.59). Aortic-valve replacement was performed in 267 patients (28.3%) in the simvastatin-ezetimibe group and in 278 patients (29.9%) in the placebo group (hazard ratio, 1.00; 95% CI, 0.84 to 1.18; P=0.97). Fewer patients had ischemic cardiovascular events in the simvastatin-ezetimibe group (148 patients) than in the placebo group (187 patients) (hazard ratio, 0.78; 95% CI, 0.63 to 0.97; P=0.02), mainly because of the smaller number of patients who underwent coronary-artery bypass grafting. Cancer occurred more frequently in the simvastatin-ezetimibe group (105 vs. 70, P=0.01). Conclusions: Simvastatin and ezetimibe did not reduce the composite outcome of combined aortic-valve events and ischemic events in patients with aortic stenosis. Such therapy reduced the incidence of ischemic cardiovascular events but not events related to aortic-valve stenosis. (ClinicalTrials.gov number, NCT00092677.)

Outcome of Patients With Low-Gradient "Severe" Aortic Stenosis and Preserved Ejection Fraction

Background-Retrospective studies have suggested that patients with a low transvalvular gradient in the presence of an aortic valve area = 55%), baseline echocardiography revealed low-gradient severe stenosis in 435 patients (29%) and moderate stenosis in 184 (12%). Left ventricular mass was lower in patients with low-gradient severe stenosis than in those with moderate stenosis (182 +/- 64 versus 212 +/- 68 g; P < 0.01). During 46 months of follow-up, aortic valve events occurred in 48.5% versus 44.6%, respectively (P=0.37; major cardiovascular events, 50.9% versus 48.5%, P=0.58; cardiovascular death, 7.8% versus 4.9%, P=0.19). Low-gradient severe stenosis patients with reduced stroke volume index (<= 35 mL/m(2); n=223) had aortic valve events comparable to those in patients with normal stroke volume index (46.2% versus 50.9%; P=0.53). Conclusions-Patients with low-gradient "severe" aortic stenosis and normal ejection fraction have an outcome similar to that in patients with moderate stenosis. (Circulation. 2011;123:887-895.