ECG Quiz 52 – Discussion

ECG Quiz 52 – Discussion

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In addition to sinus tachycardia, ST depression is noted in lateral leads I, aVL, V4-V6 (blue arrows). QS complexes are note in III and aVF (red arrows). Minimal ST depression is noted in lead (violet arrow). Mild ST elevation is noted in aVR (black arrow) and V1 (green arrow).

Overall this ECG fits in with that of an acute coronary syndrome. ST depression is indicative of subendocardial ischemia. ST elevation aVR has been given certain added significance, probably a little more than what is needed as studies have shown ST elevation in aVR with left main coronary artery occlusion. Though many of the acute left main occlusions do not reach the hospital due to sudden cardiac death, those who reach the hospital are likely to have ST elevation in aVR [1,2].

The typical finding of left main stenosis is ST elevation in aVR and V1 with reciprocal ST depression in all other leads [3]. In this ECG, ST depression is noted only in lateral leads.

ST elevation in aVR and V1 can also occur in proximal left anterior descending coronary artery occlusion proximal to first diagonal and septal. In that case, ST elevation in V1 will be more than that in aVR while the reverse occurs in left main occlusion [4]. But it may be noted that ST elevation in aVR occurred in 8% (2 out of 24 cases) of right coronary occlusions as well, possibly because of septal supply from posterolateral left ventricular branches of a large dominant right coronary artery.

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  1. Fiol M, Carrillo A, Rodríguez A, Pascual M, Bethencourt A, Bayés de Luna A. Electrocardiographic changes of ST-elevation myocardial infarction in patients with complete occlusion of the left main trunk without collateral circulation: differential diagnosis and clinical considerations. J Electrocardiol. 2012 Sep;45(5):487-90.
  2. Liang M, Kelly DJ, Devlin G. Left main stem stenosis in the unstable patient–forewarned is forearmed. N Z Med J. 2011 Jul 8;124(1338):111-3.
  3. Taglieri N, Marzocchi A, Saia F, Marrozzini C, Palmerini T, Ortolani P, Cinti L, Rosmini S, Vagnarelli F, Alessi L, Villani C, Scaramuzzino G, Gallelli I, Melandri G, Branzi A, Rapezzi C Short- and long-term prognostic significance of ST-segment elevation in lead aVR in patients with non-ST-segment elevation acute coronary syndrome. Am J Cardiol. 2011 Jul 1; 108(1):21-8.
  4. Yamaji H, Iwasaki K, Kusachi S, Murakami T, Hirami R, Hamamoto H, Hina K, Kita T, Sakakibara N, Tsuji T. Prediction of acute left main coronary artery obstruction by 12-lead electrocardiography. ST segment elevation in lead aVR with less ST segment elevation in lead V(1). J Am Coll Cardiol. 2001 Nov 1;38(5):1348-54.

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