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  • Title: Detection and quantification of acute myocardial ischemia by morphologic evaluation of QRS changes by an angle-based method.
    Author: Romero D, Ringborn M, Laguna P, Pueyo E.
    Journal: J Electrocardiol; 2013; 46(3):204-14. PubMed ID: 23538112.
    Abstract:
    OBJECTIVE: In acute myocardial ischemia changes within the QRS complex can add valuable information to that from the repolarization phase. This study evaluates three angles obtained from the main slopes of the R-wave within the QRS complex to assess acute myocardial ischemia. METHODS: The QRS angles, denoted by ØR (R-wave angle), ØU (up-stroke angle) and ØD (down-stroke angle), were evaluated in 12-lead electrocardiogram (ECG) recordings of 79 patients before and during coronary occlusion by elective percutaneous coronary intervention (PCI). In a subset of 38 patients, ischemia was quantified by myocardial scintigraphy. RESULTS: At baseline the QRS angles presented low variations. During occlusion, ØU and ØD developed a fast and abrupt change, whereas ØR showed a smaller and gradual change. There were significant correlations between both maximal and sum of positive change in ØR and ischemia: r=0.67; p<0.001 and r=0.78; p<0.001, for extent, and r=0.60; p<0.001 and r=0.73; p<0.001, for severity, respectively. Prediction of extent and severity of ischemia increased by 50% by adding ØR changes to ST-segment changes, for LCX occlusions, whereas increased by 12.1% and 24.6% for LAD and RCA occlusions, respectively. No significant correlation was seen between ØU and ØD angles and ischemia. CONCLUSIONS: Evaluation of QRS angles from the standard 12-lead ECG represents a sensitive marker for detection of acute myocardial ischemia, whereas, ØR changes can be used for prediction of its extent and severity.
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