André Schmidt

Infarct Tissue Heterogeneity by Magnetic Resonance Imaging Identifies Enhanced Cardiac Arrhythmia Susceptibility in Patients With Left Ventricular Dysfunction

Background— The extent of the peri-infarct zone by magnetic resonance imaging (MRI) has been related to all-cause mortality in patients with coronary artery disease. This relationship may result from arrhythmogenesis in the infarct border. However, the relationship between tissue heterogeneity in the infarct periphery and arrhythmic substrate has not been investigated. In the present study, we quantify myocardial infarct heterogeneity by contrast-enhanced MRI and relate it to an electrophysiological marker of arrhythmic substrate in patients with left ventricular (LV) systolic dysfunction undergoing prophylactic implantable cardioverter defibrillator placement. Methods and Results— Before implantable cardioverter defibrillator implantation for primary prevention of sudden cardiac death, 47 patients underwent cine and contrast-enhanced MRI to measure LV function, volumes, mass, and infarct size. A method for quantifying the heterogeneous infarct periphery and the denser infarct core is described. MRI indices were related to inducibility of sustained monomorphic ventricular tachycardia during electrophysiological or device testing. For the noninducible versus inducible patients, LV ejection fraction (30±10% versus 29±7%, P=0.79), LV end-diastolic volume (220±70 versus 228±57 mL, P=0.68), and infarct size by standard contrast-enhanced MRI definitions (P=NS) were similar. Quantification of tissue heterogeneity at the infarct periphery was strongly associated with inducibility for monomorphic ventricular tachycardia (noninducible versus inducible: 13±9 versus 19±8 g, P=0.015) and was the single significant factor in a stepwise logistic regression. Conclusions— Tissue heterogeneity is present and quantifiable within human infarcts. More extensive tissue heterogeneity correlates with increased ventricular irritability by programmed electrical stimulation. These findings support the hypothesis that anatomic tissue heterogeneity increases susceptibility to ventricular arrhythmias in patients with prior myocardial infarction and LV dysfunction.

Late Gadolinium Enhancement by Cardiovascular Magnetic Resonance Heralds an Adverse Prognosis in Nonischemic Cardiomyopathy

OBJECTIVES We examined whether the presence and extent of late gadolinium enhancement (LGE) by cardiovascular magnetic resonance (CMR) predict adverse outcomes in nonischemic cardiomyopathy (NICM) patients. BACKGROUND Morbidity and mortality is high in NICM patients. However, the clinical course of an individual patient is unpredictable and current risk stratification approaches are limited. Cardiovascular magnetic resonance detects myocardial fibrosis, which appears as LGE after contrast administration and may convey prognostic importance. METHODS In a prospective cohort study, 65 NICM patients with left ventricular (LV) ejection fraction < or =35% underwent CMR before placement of an implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death. The CMR images were analyzed for the presence and extent of LGE and for LV function, volumes, and mass. Patients were followed for an index composite end point of 3 cardiac events: hospitalization for heart failure, appropriate ICD firing, and cardiac death. RESULTS A total of 42% (n = 27) of patients had CMR LGE, averaging 10 +/- 13% of LV mass. During a 17-month median follow-up, 44% (n = 12) of patients with LGE had an index composite outcome event versus only 8% (n = 3) of those without LGE (p < 0.001 for Kaplan-Meier survival curves). After adjustment for LV volume index and functional class, patients with LGE had an 8-fold higher risk of experiencing the primary outcome (hazard ratio 8.2, 95% confidence interval 2.2 to 30.9; p = 0.002). CONCLUSIONS A CMR LGE in NICM patients strongly predicts adverse cardiac outcomes. The CMR LGE may represent the end-organ consequences of sustained adrenergic activation and adverse LV remodeling, and its identification may significantly improve risk stratification strategies in this high risk population. (Imaging Techniques for Identifying Factors of Sudden Cardiac Death Risk; NCT00181233).

Non-invasive half millimetre 32 detector row computed tomography angiography accurately excludes significant stenoses in patients with advanced coronary artery disease and high calcium scores

Objective: To show an overall diagnostic accuracy ⩾ 90% for detection of ⩾ 50% stenoses by coronary half millimetre 32 detector row computed tomography angiography (32 × 0.5-MDCTA) in patients with advanced coronary artery disease (CAD) and a high likelihood of raised calcium scores. Methods: ECG gated 32 × 0.5-MDCTA (32 × 0.5 mm cross sections, 0.35 × 0.35 × 0.35 mm3 isotropic voxels, 400 ms rotation) was performed after injection of iodixanol (120 ml, 320 mg/ml) in 30 consecutive patients (25 men, mean (SD) age 59 (13) years, body mass index 26.2 (4.9) kg/m2). Native arteries, including ⩾ 1.5 mm branches, and bypass grafts were screened for ⩾ 50% stenoses. Stents were excluded. Conventional coronary angiography (performed 18 (12) days before 32 × 0.5-MDCTA) was analysed by quantitative coronary angiography. Results: Median Agatston calcium score was 510 (range 3–5066). Sensitivity, specificity, and positive and negative predictive values for detection of ⩾ 50% stenoses in native arteries were 76% (29 of 38), 94% (190 of 202), 71% (29 of 41), and 96% (190 of 199), respectively. Overall diagnostic accuracy was 91% (219 of 240). Due to the following artefacts 20% (69 of 352) of the vessels were excluded: motion, noise, and low contrast enhancement isolated or in combination (45 of 69 (65%)); image distortion by implantable cardioverter-defibrillator or pacemaker leads (18 of 69 (26%)); and blooming secondary to severe calcification (6 of 69 (9%)). Conclusions: Coronary 32 × 0.5-MDCTA accurately excludes ⩾ 50% stenoses in patients with advanced CAD and high calcium scores with an overall diagnostic accuracy of 91%.

Evaluation of Cardiac Involvement During Dengue Viral Infection

BACKGROUND  Dengue is a disease whose clinical manifestations range from asymptomatic infections to a severe disease. There have been some previous reports of myocardial involvement in dengue, but this association has not been completely established. METHODS  From January to July of 2011, patients hospitalized with dengue, confirmed through dengue nonstructural protein 1 and/or immunoglobulin M detection, were included in this study and troponin I and N terminal fragment of B-type natriuretic peptide levels were determined. Patients with abnormal biomarkers underwent echocardiography and when any abnormality was detected, they underwent cardiac magnetic resonance imaging. RESULTS  Eighty-one patients were evaluated and 12 patients (15%) presented with elevated biomarker levels. Compared to controls, they had higher leukocyte (P < .001) and platelet counts (P = .005); higher C-reactive protein (P = .02), and a lower viral load (P = .03). There was no difference according to clinical dengue classification; dengue hemorrhagic fever/dengue shock syndrome severity; duration of symptoms; or prevalence of secondary infection between the 2 groups. Two patients died secondary to cardiogenic shock before imaging studies. Necroscopic findings were compatible to myocarditis in both, and immunohistochemistry for dengue virus showed increased staining on mononuclear cells located in the myocardial tissue. Of the 10 patients who underwent echocardiography, depressed left ventricular ejection fraction (LVEF) was identified in 1, left ventricular segmental abnormalities with preserved LVEF in 2, and an important pericardial effusion with tamponade in another. Cardiac involvement was confirmed by CMR in these 4 patients. CONCLUSIONS  Dengue viruses were shown to cause cardiac disease with clinical manifestations ranging from mild elevation of biomarkers to myocarditis and/or pericarditis.

Imaging Diagnosis of Right Ventricle Involvement in Chagas Cardiomyopathy

Right ventricle (RV) is considered a neglected chamber in cardiology and knowledge about its role in cardiac function was mostly focused on ventricular interdependence. However, progress on the understanding of myocardium diseases primarily involving the RV led to a better comprehension of its role in health and disease. In Chagas disease (CD), there is direct evidence from both basic and clinical research of profound structural RV abnormalities. However, clinical detection of these abnormalities is hindered by technical limitations of imaging diagnostic tools. Echocardiography has been a widespread and low-cost option for the study of patients with CD but, when applied to the RV assessment, faces difficulties such as the absence of a geometrical shape to represent this cavity. More recently, the technique has evolved to a focused guided RV imaging and myocardial deformation analysis. Also, cardiac magnetic resonance (CMR) has been introduced as a gold standard method to evaluate RV cavity volumes. CMR advantages include precise quantitative analyses of both LV and RV volumes and its ability to perform myocardium tissue characterization to identify areas of scar and edema. Evolution of these cardiac diagnostic techniques opened a new path to explore the pathophysiology of RV dysfunction in CD.

Presence of scar by late gadolinium enhancement is a strong predictor of events in Chagas Heart Disease

Methods A total of 121 patients with CHD disease (52.1% female; 54.5 ± 13 years-old) from Ribeirao Preto Clinical Hospital (Sao Paulo, Brazil) were included. A CMR was performed at the enrollment from October/2009 to March/2013 in a single 1.5T scanner (Achieve, Phillips, the Netherlands), including SSFP cines at the vertical and horizontal long axis, and a stack of the short axis. LGE sequences were performed after 10.1 ± 1.5 min gadolinium contrast (0.2 mmol/kg) in the same cine positions, with positive LGE visually assessed and quantified for core and grey zone. All analysis was performed with Mass Research version software (Leiden University, the Netherlands). Any death, pacemaker (PC) implant and heart failure hospitalization (HFH) was considered an event during the follow-up. Kaplan-Meier curves, log-rank analysis and Cox regression models were utilized at the statistical analysis.

Left Internal Thoracic Artery Graft to Left Anterior Descending Coronary Artery after Blunt-Chest-Trauma Myocardial Infarction: 14-Year Outcome

In 2005, we reported an acute myocardial infarction secondary to a left anterior descending coronary artery injury sustained in a motorcycle accident. The treatment was late myocardial revascularization with in situ left internal thoracic artery-to-left anterior descending coronary artery anastomosis. There is little information available about the natural history of acute myocardial infarction after blunt chest trauma, especially when treated in this manner. This present communication reports the 14-year outcome in our patient.

Speculative Considerations about Some Cardiology Enigmas

Background: Enigmas often lead to hypotheses and speculations. For this reason, especially for the sake of the reader’s motivation, we opted for the plain discussion of some cardiology enigmas. Objective: The present text was aimed to discuss speculatively some cardiology enigmas. Method: Text was freely designed in the context of coronary artery and heart valve diseases. Results: The results were presented as the combination enigma/hypothesis. 1) The absence of arteriosclerosis in intramyocardial coronary arteries/ endothelium-myocardial interaction (crosstalk); 2) The unique and always confirmed superior evolution of the internal thoracic artery as coronary graft/ higher NO basal release 3) The prophylactic left internal thoracic artery graft in mildly-stenosed coronary lesions/need of more accurate functional imaging techniques; 4) The high incidence of perioperative atrial fibrillation in patients with coronary artery disease/atrial ischemia associated to left circumflex coronary lesions; 5) The handling of disease-free saphenous vein grafts at the time of re-operation/biological serendipity with graft vein segments; 6) The possible aortic stenosis protection against coronary artery disease/ endothelium myocardium interaction (crosstalk) improving NO release. Conclusion: The discussed topics associated with their respective speculative hypothesis remain as enigmas, but would become motivations for investigations

Influence of aerobic exercise training on left ventricular remodeling and neurohumoral response in patients with myocardial infarction

Purpose: The effects of aerobic training on ventricular remodeling (VR) and neurohumoral activation after myocardial infarction (MI) have not been completely elucidated. It was investigated the influence of aerobic training on physical fitness, on VR and neurohumoral response after MI. Methods: Sixteen patients with anterior wall myocardial infarction were randomized into two groups: training (TG=8) and control (CG=8). TG patients performed moderate-intensity aerobic training. Before and after a 12-week follow-up all patients underwent cardiac magnetic resonance, cardiopulmonary exercise testing and blood sampling for measurement of NT-proBNP. Results: In the follow-up, there was a significant increase in the ΔO2 pulse in the TG (6.4 ± 1.2 to 8.1 ± 1.7; p=0.01), with no significant change in the CG (7.0 ± 2.3 to 6.9 ± 3.0; p>0.99). It was observed an increase of LV mass/EDV ratio from 0.72 ± 0.19 to 0.96 ± 0.30 g.ml-1 (p=0.007) in the CG, but no change in the TG from 0.89 ± 0.33 to 0.96 ± 0.26 g.ml-1 (p=0.54). There was a significant decrease of NT-proBNP at rest and at effort peak in both groups. Conclusion: Aerobic training seems to have a protective effect over the spontaneous process of LV concentric remodeling after myocardial infarction, and it promotes an improvement of the LV systolic performance during dynamic physical effort, without triggering adverse neurohumoral activation. Correspondence to: Giovani Luiz De Santi, Division of Cardiology, Medical School of Ribeirao Preto, University of Sao Paulo, Av. Bandeirantes, n 3.900, Ribeirao Preto-SP, Brazil, Zip: 14048-900; Tel: +551636022599, +551636022782, +553498020315; Fax: +551636021504; E-mail: giovanidesanti@usp.br

Aortic Regurgitation Quantification using Cardiac Magnetic Resonance. Is there a best imaging plane for flow quantification? A single center clinical trial

Background The precise quantification of aortic regurgitation (AR) is central to surgical planning. Some authors suggest early intervention in asymptomatic patients with severe AR. With the advent of transcatheter aortic valve implantation (TAVI), the identification and precise quantification of paravalvular regurgitation is also paramount. In routine clinical practice, the imaging plane used for flow analysis by phase contrast (PC) technique is the sinotubular junction (STJ) in the ascending aorta. However, this plane is not suitable in cases with TAVI. The other two used planes are the ascending aorta (AAo) and the left ventricle outflow tract (LVOT), but these are said to respectively, overestimate and underestimate the measurements. Objective: to compare the volumes of three different planes of measurement in the AAo, JST and LVOT, in patients with different degrees of AR.