Evaluation of QRST isointegral maps in detecting posterior myocardial infarction with and without conduction disturbance

ECG criteria in diagnosis of acute myocardial infarction in the presence of left bundle branch block

BACKGROUND

The diagnosis of acute myocardial infarction in the presence of left bundle branch block is difficult. Recently a diagnostic ECG scoring system was suggested, showing good diagnostic abilities. This scoring system has never been tested in a prospective manner; we have done so and investigated if it might bear prognostic information.

METHODS

A prospective multi-centre study. Consecutive patients with left bundle branch block and suspicion of acute myocardial infarction, admitted to 14 Swedish coronary care units. Recruitment from March 1996 to December 1997. ECG registered on admission and after 12-24 h.

RESULTS

One hundred and fifty-eight patients were included, mean age 74.9 years. Seventy-six patients (48%) had an acute myocardial infarction. The proposed cut-off total score of > or = 3 of the ECG scoring system for the diagnosis of acute myocardial infarction had a sensitivity of 17.1% (95% CI 8.6-25.6%) and specificity of 94.0% (95% CI 88.9-99.1%). Clinical judgement of acute myocardial infarction resulted in a sensitivity of 15.8% (95% CI 7.6-24%) and specificity of 96.0% (CI 92.3-100%). No difference was seen in 3-month or 1-year survival between those with total ECG score > or = 3 versus total score < 3.

CONCLUSION

The diagnostic abilities of the proposed ECG criteria are low and not better than the clinical judgement. The criteria are therefore not suitable for screening patients with suspicion of acute myocardial infarction in the presence of left bundle branch block, nor do they seem to identify high risk patients.

Characteristic findings of body surface potential map during ventricular repolarization in patients with coronary heart disease

The objective of the present study was to investigate the characteristics of body surface potential map (BSPM) findings during ventricular repolarization in patients with coronary artery disease (CAD). A total of 108 consecutive patients, 99 men and 9 women with angina pectoris and positive treadmill exercise test results as well as angiographically documented CAD underwent BSPM study in a fasting state. Their ages ranged from 30 to 70 years. There were 13 patients with right coronary artery (RCA) lesions, 37 with left anterior descending artery (LAD) lesions, 5 with left circumflex artery (LCX) lesions, 17 with both RCA and LAD lesions, 12 with both LCX and LAD lesions, and 24 with 3-vessel disease. The BSPMs were obtained by using the heart potential map system designed by Toyama et al. There were 59 lead points on the anterior chest wall and 28 on the back. The BSPMs in isopotential distribution were made every one msec throughout the ventricular activation period. The distribution of positive and negative potentials, potential maximum and potential minimum, polarity of potential distribution, and the reversal of potential distribution during ventricular repolarization were analyzed. The following information on BSPMs was obtained: (1) In early ventricular repolarization, the negative potential and the potential minimum appeared abnormally on the anterior thorax. The potential abnormality displayed on the right portion or the inferior portion in patients with RCA lesions, on the middle portion or the left portion in patients with LAD lesions, and on the left-superior portion or the left-middle portion in patients with LCX lesions. In patients with multi-vessel disease, the abnormal potential distribution showed a combined pattern of individual vessel lesions. (2) In some cases, the multipolar potential distribution appeared abnormally during the initial stage and the peak of the T wave. (3) The reversal of potential distribution was observed in about half of the patients. The characteristic findings of the BSPM during ventricular repolarization, including abnormal potential distribution, multipolar potential distribution and reversal of potential distribution, will be of clinical value in patients with CAD.