Journal of the Louisiana State Medical Society
lead aVR. Chest 2002;122:134-139.
ECG of the Month Presentation is on p 219.
DIAGNOSIS: Sinus rhythm (rate, 97 beats/min); two episodes of AV dissociation with an accelerated idioventricular rhythm (rate, 103 beats/min) dissociated from sinus rhythm; the two rhythms produce numerous fusion QRS complexes; acute inferoposterior myocardial infaraction; left atrial enlargement. The first QRS is sinus-initiated. The second through the eighth QRS complexes are fusion complexes that progres- sively look more like accelerated idioventricular complexes and less like sinus-initiated complexes. The ninth QRS is a ventricular premature complex, and the next three complex- es are sinus-initiated. The last five QRSs are fusions, again looking progressively more like accelerated idioventricular complexes and less like sinus-initiated complexes. Qwaves with ST-segment elevation in the inferior leads and tall Rwaves with ST-segment depression in the anterior precordial leads indicate acute inferoposterior myocardial infarction. Accelerated idioventricular rhythm is common with acute myocardial infarction, and, in contrast to ven- tricular tachycardia, does not worsen prognosis. 1 P-wave duration >0.12 s in the inferior leads suggests left atrial enlargement. In acute inferior myocardial infarctioin, the culprit le- sion is in the right coronary artery four times as often as it is in the left circumflex coronary artery. 2-4 In this patient, how- ever, four findings suggest that the left circumflex coronary artery is the culprit: ST elevation in lead I, ST elevation lead II > lead III, ST depression V 1 and V 2 , and ST depression >1 mm (0.1 mV) in lead aVR. 4 The patient was initially seen at another hospital where the ECG was performed, and the peak CK level was 1,764 U/L (reference < 230) with an MB fraction of 626 ng/ml (reference < 4.0). His coronary arte- riograms at our institution four days later showed 70% nar- rowing of the left anterior descending coronary artery in its midportion, 80% narrowing of the mid-left circumflex, and 80-90% narrowing of the mid-right. Both the left circumflex and the right coronary arterial lesions were stented. REFERENCES 1. O’Keefe JH Jr, Hammill SC, Freed MS, et al. The Complete Guide to ECGs. A Comprehensive Study Guide to Improve ECG Interpretation Skills , 2nd edition. Royal Oak, Michigan: Physicians’ Press;2002:491. 2. Birnbaum Y, Wagner GS, Barbash GI, et al. Correlation of angiographic findings and right (V1 to V3) versus left (V4 to V6) precordial ST-segment depression in inferior wall acute myocardial infarction. Am J Cardiol 1999;83:143-148. 3. Correale E, Battista R, Martone A, et al. Electrocardiographic patterns in acute inferior myocardial infarction with and without right ventricle involvement: classification, diagnostic and prognostic value, masking effect. Clin Cardiol 1999;22:37-44. 4. Nair R, Glancy DL. ECG discrimination between right and left circumflex coronary arterial occlusion in patients with acute inferior myocardial infarction. Value of old criteria and use of
Dr. Glancy is a Professor of Medicine and Dr. McShurley is a Fellow of Cardiovascular Diseases at the Louisiana State University Health Sciences Center in New Orleans.
220 J La State Med Soc VOL 166 September/October 2014
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