The 12-lead ECG has limited utility to predict the risk for sudden cardiac death in common cardiac diseases such as coronary artery disease and idiopathic dilated cardiomyopathy. However, it is quite useful in diagnosing less common cardiac conditions that are associated with an increased risk for sudden death.
[Show abstract][Hide abstract] ABSTRACT: The causes of syncope are usually benign but are occasionally associated with significant morbidity and mortality. We derive a decision rule that would predict patients at risk for short-term serious outcomes and help guide admission decisions.
This prospective cohort study was conducted at a university teaching hospital and used emergency department (ED) patients presenting with syncope or near syncope. Physicians prospectively completed a structured data form when evaluating patients with syncope. Serious outcomes (death, myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage, or any condition causing a return ED visit and hospitalization for a related event) were defined at the start of the study. All patients were followed up to determine whether they had experienced a serious outcome within 7 days of their ED visit. Univariate analysis was performed with chi2 and nonparametric techniques on all predictor variables. kappa Analysis was performed on variables requiring interpretation. Variables with kappa more than 0.5 and a P value less than.1 were analyzed with recursive partitioning techniques to develop a rule that would maximize the determination of serious outcomes.
There were 684 visits for syncope, and 79 of these visits resulted in patients' experiencing serious outcomes. Of the 50 predictor variables considered, 26 were associated with a serious outcome on univariate analysis. A rule that considers patients with an abnormal ECG, a complaint of shortness of breath, hematocrit less than 30%, systolic blood pressure less than 90 mm Hg, or a history of congestive heart failure has 96% (95% confidence interval [CI] 92% to 100%) sensitivity and 62% (95% CI 58% to 66%) specificity. If applied to this cohort, the rule has the potential to decrease the admission rate by 10%.
The San Francisco Syncope Rule derived in this cohort of patients appears to be sensitive for identifying patients at risk for short-term serious outcomes. If prospectively validated, it may offer a tool to aid physician decision making.
Annals of emergency medicine 03/2004; 43(2):224-32. DOI:10.1016/S0196064403008230 · 4.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A dynamic model is proposed to study the relationship between the QT and RR intervals of the surface electrocardiogram. The
model accounts for the influence of a history of previous RR intervals on each QT, considering that such an influence may
vary along the recording time. For identification of the model parameters, an adaptive methodology that uses the regularized
Kalman filter is developed. A set of risk markers are derived from the estimated model parameters and they are tested on ambulatory
recordings of postmyocardial infarction patients randomized to treatment with amiodarone or placebo. The results of our study
show that amiodarone substantially modifies the QT interval response to heart rate changes. Furthermore, the way amiodarone
acts on QT adaptation allows to identify patients in which treatment is being effective and separate them from those in which
it is not and, consequently, are at higher risk of suffering from arrhythmic death.
[Show abstract][Hide abstract] ABSTRACT: Syncope is a common and challenging presentation for the emergency physician. Various investigators have developed clinical risk score and clinical decision rules which are designed to identify the population at highest risk for adverse events. In each of these clinical decision tools, the electrocardiogram (ECG) is one of the key clinical variables used to evaluate the patient. Certain electrocardiographic presentations in the patient with syncope will not only provide a reason for the loss of consciousness but also guide early therapy and disposition in this individual. Bradycardia, atrioventricular block, intraventricular conduction abnormality, and tachydysrhythmia in the appropriate clinical setting provide an answer to the clinician for the syncopal event. Morphologic findings suggesting the range of cardiovascular malady are also encountered; these entities are far ranging, including the various ST-segment and T-wave abnormalities of acute coronary syndrome, ventricular preexcitation as seen in the Wolff-Parkinson-White syndrome, Brugada syndrome with the associated tendency for sudden death, prolonged QT interval common in the diverse long QT interval presentations, and right ventricular hypertrophy suggestive of hypertrophic cardiomyopathy. This review discusses the ECG in the patient with syncope. The general use of the 12-lead ECG in this patient population is discussed. Furthermore, specific electrocardiographic presentations seen in the patient with syncope are also reviewed.
The American journal of emergency medicine 08/2007; 25(6):688-701. DOI:10.1016/j.ajem.2006.12.016 · 1.27 Impact Factor
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