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Abu Dhabi, United Arab Emirates

Alsheikh-Ali A.A.,Institute of Cardiac science | Kitsios G.D.,Institute for Clinical Research and Health Policy Studies | Balk E.M.,Institute for Clinical Research and Health Policy Studies | Lau J.,Institute for Clinical Research and Health Policy Studies | Ip S.,Institute for Clinical Research and Health Policy Studies
Annals of Internal Medicine | Year: 2010

The scope of recent literature on the concept of "vulnerable plaque" was reviewed by examining 463 abstracts of primary and review articles identified through MEDLINE (2003 to April 2010). Proposed definition criteria of vulnerable plaque included active inflammation, a thin cap with a large lipid core, endothelial denudation, fissured cap, severe stenosis, or combinations of these findings. In 242 primary studies, histopathology, biomarkers, and imaging of carotid and coronary artery plaques were evaluated for features suggestive of vulnerability. Notably, 89% of these studies were cross-sectional in design and were exclusively conducted in patients with known cardiovascular disease. None of the imaging studies documented whether the identified lesions were responsible for cardiovascular events. Cross-sectional design precludes evaluation of the predictive utility of biomarkers. Because vulnerable plaque is not an established medical diagnosis, no studies have been done that explicitly evaluate the treatment of vulnerable plaques. Few studies examined potential systemic treatments (for example, statins) to modify vulnerability features. Large prospective studies in patients with and without previous cardiovascular events during long follow-up are required to validate this concept. © 2010 American College of Physicians. Source


Madias C.,Rush University Medical Center | Fitzgibbons T.P.,University of Massachusetts Medical School | Alsheikh-Ali A.A.,Institute of Cardiac science | Alsheikh-Ali A.A.,Institute for Clinical Research and Health Policy Studies | And 7 more authors.
Heart Rhythm | Year: 2011

Background: Stress cardiomyopathy (SCM) is a syndrome of transient ventricular dysfunction triggered by severe emotional or physical stress, likely resulting from catecholamine-mediated myocardial toxicity. Repolarization abnormalities associated with other hyperadrenergic states can cause QT prolongation and lethal arrhythmia including torsades de pointes (TdP). Despite the development of repolarization abnormalities and QT prolongation in SCM, little is known about the risk of ventricular fibrillation (VF) and TdP. Objective: The aim of this study was to assess the prevalence and clinical predictors of ventricular arrhythmias in a cohort of patients with SCM. Methods: Data from a registry of consecutive patients with SCM from 2 institutions were reviewed. Patients who developed VF or TdP were identified. Clinical characteristics and outcomes were analyzed and compared with a control group of patients with SCM without VF/TdP. Results: Of 93 patients with SCM, 8 (8.6%) experienced VF/TdP. Of these 8 patients, 2 presented with VF and were subsequently diagnosed with SCM. Six other patients experienced pause-dependent TdP or VF after SCM diagnosis in the setting of substantial QT prolongation. Prolongation of the corrected QT interval (QTc) was significantly associated with the occurrence of ventricular arrhythmia (odds ratio 1.28 for each 10 ms increase in QTc, 95% confidence interval 1.10 to 1.50). Conclusion: SCM can be associated with life-threatening ventricular arrhythmia in over 8% of cases. SCM should be recognized among the causes of acquired long QT syndrome and can be associated with a risk of TdP. © 2011 Heart Rhythm Society. Source


Haffajee J.A.,Tufts Medical Center | Lee Y.,Tufts University | Alsheikh-Ali A.A.,Tufts University | Alsheikh-Ali A.A.,Institute of Cardiac science | And 3 more authors.
JACC: Cardiovascular Imaging | Year: 2011

Objectives: The purpose of this study was to examine whether left atrial (LA) mechanical function, as measured by LA total emptying fraction (TEF), is a predictor for the development of post-operative atrial fibrillation (POAF) following cardiac surgery. Background: POAF is an important and frequent complication of cardiac surgery. LA enlargement has been reported to be a risk factor for POAF, but the relationship between LA mechanical function and POAF is not well understood. We examined the relationship between pre-operative LA function and POAF in patients without a history of atrial fibrillation. Methods: A total of 101 subjects (mean age 64 ± 13 years) underwent pre-operative transthoracic echocardiograms and were followed for occurrence of POAF during the hospitalization for cardiac surgery. The left atrial maximum volume (LAVmax) and left atrial minimum volume (LAVmin) were measured and indexed to body surface area (LAVmaxI and LAVminI, respectively). LA TEF was calculated as: {[(LAVmax LAVmin)/LAVmax] × 100%}. Univariate and multivariate analyses examined clinical and echocardiographic predictors of POAF. Results: POAF occurred in 41% of subjects. Mean LA TEF was 49 ± 15%, mean LAVmaxI was 38 ± 15 ml/m 2, and mean LAVminI was 20 ± 13 ml/m 2. Age, LA TEF, and LAVminI were independent predictors of POAF. LA TEF was lower in patients with POAF compared with those without POAF (43 ± 15% vs. 55 ± 13%, p < 0.001), and patients with a LA TEF <50% had a high risk of POAF (odds ratio: 7.94, 95% confidence interval: 3.23 to 19.54, p < 0.001). Compared with LAVmaxI >32 ml/m 2, LA TEF <50% had higher discriminatory power for POAF, which remained significantly higher when adjusted for age (p = 0.04). Conclusions: LA TEF is an independent predictor of POAF and is a stronger predictor of POAF than LAVmaxI is. Impaired LA mechanical function may help to identify patients who are most likely to benefit from prophylaxis for POAF. © 2011 American College of Cardiology Foundation. Source


Jafri H.,Molecular Cardiology Research Institute | Alsheikh-Ali A.A.,Tufts University | Alsheikh-Ali A.A.,Institute of Cardiac science | Karas R.H.,Molecular Cardiology Research Institute
Journal of the American College of Cardiology | Year: 2010

Objectives: We sought to examine the relationship between high-density lipoprotein cholesterol (HDL-C) levels and the risk of the development of cancer in large randomized controlled trials (RCTs) of lipid-altering interventions. Background: Epidemiologic data demonstrate an inverse relationship between serum total cholesterol levels and incident cancer. We recently reported that lower levels of low-density lipoprotein cholesterol are associated with a significantly higher risk of incident cancer in a meta-analysis of large RCTs of statin therapy. However, little is known about the relationship between HDL-C levels and cancer risk. Methods: A systematic MEDLINE search identified lipid intervention RCTs with ≥1,000 person-years of follow-up, providing baseline HDL-C levels and rates of incident cancer. Using random-effects meta-regressions, we evaluated the relationship between baseline HDL-C and incident cancer in each RCT arm. Results: A total of 24 eligible RCTs were identified (28 pharmacologic intervention arms and 23 control arms), with 625,477 person-years of follow-up and 8,185 incident cancers. There was a significant inverse association between baseline HDL-C levels and the rate of incident cancer (p = 0.018). The inverse association persisted after adjusting for baseline low-density lipoprotein cholesterol, age, body mass index (BMI), diabetes, sex, and smoking status, such that for every 10-mg/dl increment in HDL-C, there was a 36% (95% confidence interval: 24% to 47%) relatively lower rate of the development of cancer (p < 0.001). Conclusions: There is a significant inverse association between HDL-C and the risk of incident cancer that is independent of LDL-C, age, BMI, diabetes, sex, and smoking. © 2010 American College of Cardiology Foundation. Source


Kalin J.,Cardiac Arrhythmia Center | Madias C.,Rush University Medical Center | Alsheikh-Ali A.A.,Institute of Cardiac science | Alsheikh-Ali A.A.,Tufts University | Link M.S.,Cardiac Arrhythmia Center
Heart Rhythm | Year: 2011

Background: Sudden death due to low-energy blunt trauma to the precordium (commotio cordis) has been described with a variety of sporting objects. However, the risk of ventricular fibrillation (VF) relative to the shape of the impact object is not known. Objective: The objective of the current experiment is to test whether the impact object shape is a clinical variable that affects the risk for commotio cordis. Methods: In a juvenile swine model, impacts were given in random order with two different spherical shapes (72 mm diameter, equivalent to a baseball; 42 mm diameter, equivalent to a golf ball) and a flat round object 72 mm in diameter. Objects were equal in weight (150 g), thrown at 30 mph, and gated to the vulnerable portion of the cardiac cycle. Results: Sixteen swine received 144 impacts. The flat object did not cause VF (P =.01 compared with the two spherical objects), nonsustained VF, ST elevation, or bundle branch block. The smaller diameter sphere caused VF in nine of 48 impacts (19%), and the larger diameter sphere caused VF in five of 48 impacts (10%; P =.25). The smaller diameter sphere was associated with a greater increase in left ventricular pressure (P <.0001 and P =.001 compared with larger sphere only) and a higher likelihood of ST segment elevations (P <.001 and P =.08 compared with larger sphere only) and bundle branch block (Fisher's exact P =.008, and Fisher's exact P =.18 compared with larger sphere only). Conclusion: The shape of the projectile markedly influences the risk of VF from chest wall impact. This effect is likely mediated via a greater increase in left ventricular pressure with smaller diameter objects. Spreading the impact force over a larger area may decrease the risk of sudden death and has implications for the design of protective athletic equipment. © 2011 Heart Rhythm Society. Source

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