Journal of electrocardiology
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Analyzing cardiac rhythm in the presence of chest compression artifact for automated shock advisory.
Defibrillation is often required to terminate a ventricular fibrillation or fast ventricular tachycardia rhythm and resume a perfusing rhythm in sudden cardiac arrest patients. Automated external defibrillators rely on automatic ECG analysis algorithms to detect the presence of shockable rhythms before advising the rescuer to deliver a shock. For a reliable rhythm analysis, chest compression must be interrupted to prevent corruption of the ECG waveform due to the artifact induced by the mechanical activity of compressions. ⋯ Using this method only a small percentage of cases need compressions interruption, hence a significant reduction in hands-off time is achieved. Our algorithm comprises a novel filtering technique for the ECG and thoracic impedance waveforms, and an innovative method to combine analysis from both filtered and unfiltered data. Requiring compression interruption for only 14% of cases, our algorithm achieved a sensitivity of 92% and specificity of 99%.
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Pre-hospital 12-lead ECG interpretation is important because pre-hospital activation of the coronary catheterization laboratory reduces ST-segment elevation myocardial infarction (STEMI) discovery-to-treatment time. In addition, some ECG features indicate higher risk in STEMI such as proximal left anterior descending (LAD) culprit lesion location. The challenging nature of the pre-hospital environment can lead to noisier ECGs which make automated STEMI detection difficult. We describe an automated system to classify lesion location as proximal LAD, LAD, right coronary artery (RCA) and left circumflex (LCx) and test the performance on pre-hospital 12-lead ECG. ⋯ Although our test database is not large, algorithm performance suggests culprit lesion location can be reliably determined from pre-hospital ECG. Further research is needed however to evaluate the impact of automated culprit lesion location on patient treatment and outcomes.
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Takotsubo cardiomyopathy (TC) is a recently recognized novel cardiac syndrome characterized by transient left ventricular dysfunction without obstructive coronary disease, electrocardiographic (ECG) changes (ST-segment elevation and/or negative T wave) or elevated cardiac enzymes. Because the clinical features and ECG findings of TC mimic those of anterior acute myocardial infarction (AMI) with occlusion of the left anterior descending coronary artery, differential diagnosis has an important role in selecting the most appropriate treatment strategy. ⋯ Although it has been suggested that ECG does not allow reliable differentiation between TC and anterior AMI, several ECG criteria distinguishing TC from anterior AMI have been proposed. In this review, we discuss ECG findings of TC, especially in the acute phase, compare them with those of anterior AMI, and identify ECG features that may facilitate early recognition of this disease.
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Comparative Study
Differences in ST-elevation and T-wave amplitudes do not reliably differentiate takotsubo cardiomyopathy from acute anterior myocardial infarction.
Previous efforts to distinguish acute anterior ST-elevation myocardial infarction (anterior-STEMI) from various forms of takotsubo cardiomyopathy (TTC) by electrocardiography (ECG) have produced differing results. ⋯ In patients with anterior ST-elevation and acute chest pain, lack of ST-elevation in lead V1 and ST-elevation amplitude <2mm in lead V2 suggests a TTC diagnosis. However, this criterion is not reliable enough in clinical practice to distinguish between TTC and anterior-STEMI patients.
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Cornell product criteria, Sokolow-Lyon voltage criteria and electrocardiographic (ECG) strain (secondary ST-T abnormalities) are markers for left ventricular hypertrophy (LVH) and adverse prognosis in population studies. However, the relationship of regression of ECG LVH and strain during antihypertensive therapy to cardiovascular (CV) risk was unclear before the Losartan Intervention for Endpoint Reduction in Hypertension (LIFE) study. We reviewed findings on ECG LVH regression and strain over time in 9193 hypertensive patients with ECG LVH at baseline enrolled in the LIFE study. ⋯ After controlling for treatment with losartan or atenolol, for baseline Framingham risk score, Cornell product, and Sokolow-Lyon voltage, and for baseline and in-treatment systolic and diastolic blood pressure, 1 standard deviation (SD) lower in-treatment Cornell product was associated with a 14.5% decrease in the composite endpoint (HR. 0.86, 95% CI [0.82-0.90]). In a parallel analysis, 1 SD lower in-treatment Sokolow-Lyon voltage was associated with a 16.6% decrease in the composite endpoint (HR. 0.83, 95% CI [0.78-0.88]). The LIFE study shows that evaluation of both baseline and in-study ECG LVH defined by Cornell product criteria, Sokolow-Lyon voltage criteria or ECG strain improves prediction of CV events and that regression of ECG LVH during antihypertensive treatment is associated with better outcome, independent of blood pressure reduction.