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Detection and quantification of acute myocardial ischemia by morphologic evaluation of QRS changes by an angle-based method

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 ∅R (R-wave angle), ∅U (up-stroke angle) and ∅D (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, ∅U and ∅D developed a fast and abrupt change, whereas ∅R showed a smaller and gradual change. There were significant correlations between both maximal and sum of positive change in ∅R 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. Pbkp_rediction of extent and severity of ischemia increased by 50% by adding ∅R 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 ∅U and ∅D 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, ∅R changes can be used for pbkp_rediction of its extent and severity. © 2013 Elsevier Inc.