Time course of infarct healing and left ventricular remodelling in patients with reperfused ST segment elevation myocardial infarction using comprehensive magnetic resonance imaging.
ABSTRACT To describe the time course of myocardial infarct (MI) healing and left ventricular (LV) remodelling and to assess factors predicting LV remodelling using cardiac MRI.
In 58 successfully reperfused MI patients, MRI was performed at baseline, 4 months (4M), and 1 year (1Y) post MI RESULTS: Infarct size decreased between baseline and 4M (p < 0.001), but not at 1Y; i.e. 18 ± 11%, 12 ± 8%, 11 ± 6% of LV mass respectively; this was associated with LV mass reduction. Infarct and adjacent wall thinning was found at 4M, whereas significant remote wall thinning was measured at 1Y. LV end-diastolic and end-systolic volumes significantly increased at 1Y, p < 0.05 at 1Y vs. baseline and vs. 4M; this was associated with increased LV sphericity index. No regional or global LV functional improvement was found at follow-up. Baseline infarct size was the strongest predictor of adverse LV remodelling.
Infarct healing, with shrinkage of infarcted myocardium and wall thinning, occurs early post-MI as reflected by loss in LV mass and adjacent myocardial remodelling. Longer follow-up demonstrates ongoing remote myocardial and ventricular remodelling. Infarct size at baseline predicts long-term LV remodelling and represents an important parameter for tailoring future post-MI pharmacological therapies designed to prevent heart failure.
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ABSTRACT: Cardiac magnetic resonance imaging (MRI) has emerged as a prime player in the clinical and preclinical detection of ischemic heart disease (IHD) as well in the prognosis assessment by offering a comprehensive approach for all spectrums of coronary artery disease (CAD) patients. The aim of this review is to provide the reader a state–of–the art on how the newest cardiac MRI techniques can be used to study IHD patients.In patients with suspected/stable CAD, functional and perfusion imaging both at rest and during vasodilatatory stress (adenosine, dypiridamole)/dobutamine stress can accurately depict ischemic myocardium secondary to significant coronary artery stenosis.In patients with acute MI, MRI is a robust tool for differentiating and sizing the jeopardized and the infarcted myocardium by using a combination of functional, edema, perfusion and Gd contrast imaging. Moreover, important prognostic factors like myocardial salvage, the presence of microvascular obstruction (MVO), post reperfusion myocardial hemorrhage, RV involvement and infarct related complications can be assessed in the same examination. In patients with chronic ischemic cardiomyopathy, the role of the MRI extends from diagnosis by means of Gadolinium contrast scar imaging to therapy and prognosis by functional assessment and viability testing with rest and dobutamine stress imaging.In all the circumstances mentioned, MRI derived information has been proven valuable in every day clinical decision making and prognosis assessment. Thus, MRI is becoming more and more an accepted alternative to other imaging modalities both in the acute and chronic setting.Journal of medicine and life 11/2011; 4(4):330-45.
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ABSTRACT: Cardiac remodelling following myocardial infarction (MI) is a complex, dynamic process. There have been few longitudinal studies of these changes. A 2-dimensional transthoracic echocardiography was performed on 20 rabbits, before and 1, 2, 4, 8, and 12 weeks after MI (n = 14) and twice for controls (n = 6). Chronic left ventricular (LV) infarct size was histologically characterized and correlated with mechanical function. A linear mixed model was used to analyze longitudinal and infarct size-related changes in LV end-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF), sphericity, circumferential strain, and wall motion score index. Mean LV infarct size was 28.9% ± 9.3%. After MI, rapid remodelling occurred in LVESV, LVEF, and sphericity for 2 weeks and LVEDV for 4 weeks, with slower changes afterwards. LV infarct size correlated with LVESV (r = 0.76), LVEDV (r = 0.71), and LVEF (r = 0.69). Larger infarcts resulted in greater LVESV dilation (P = 0.04) and faster LVEDV (P < 0.01), LVEF (P < 0.01), and sphericity (P < 0.01) remodelling. Apical global circumferential strain and wall motion score index increased for 1 week, then stabilized, regardless of infarct size, and apical global circumferential strain was correlated with apical infarction (r = 0.58). Additionally, regional circumferential strain decreased in segments with severe (> 80%) infarction more quickly (P < 0.01) and by a greater degree (P = 0.04) compared with segments with minor (< 20%) infarction. The most dynamic remodelling of cardiac function in this model occurred during the first 4 weeks, stabilizing thereafter, with changes maintained up to 12 weeks. Infarct size affected both the early rate and long-term extent of mechanical remodelling.The Canadian journal of cardiology 01/2012; 28(2):230-8. DOI:10.1016/j.cjca.2011.11.003 · 3.94 Impact Factor
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ABSTRACT: Recently, we demonstrated the feasibility and safety of circular electroporation ablation in porcine pulmonary vein ostia, but the relationship between the magnitude of the application and lesion dimensions is still unknown. An in vivo porcine study was performed on left ventricular epicardium submerged under 10 mm of blood, using devices that mimic a 20-mm-diameter 7F circular ablation catheter. Model D contained 10 separate electrodes, whereas model M consisted of 1 circular electrode. Ablations were performed at 50, 100, and 200 J with model D and at 100 J with model M. Lesion dimensions were measured after 3-week survival. All applications resulted in smooth voltage waveforms demonstrating the absence of vapor globe formation, arcing, and a pressure wave. Applications up to 100 J with model D resulted in separate lesions under the electrodes. At 200 J, continuous deep circular lesions were created despite the use of separate electrodes. There was a significant relationship between applied current and median lesion depth, with a slope of 0.17 mm/A. At 100 J, there was no difference in lesion depth or width between models D and M. The electrodes and ablation site directly after ablation showed no signs of thermal damage. In an epicardial porcine model with blood around the application site, continuous circular lesions, deep enough for electric pulmonary vein isolation, were created with a single circular 200-J application. Lesions were continuous despite the use of separate electrodes. Lesion depth increased with the magnitude of the application.Circulation Arrhythmia and Electrophysiology 04/2012; 5(3):581-6. DOI:10.1161/CIRCEP.111.970079 · 5.42 Impact Factor