Acute diagonal-induced ST-elevation myocardial infarction and electrocardiogram-guidance in the era of primary coronary intervention: New insights into an old tool.

Background: Previous studies, published before the advent of primary reperfusion, described the electrocardiographic features of ST-segment elevation myocardial infarction (STEMI) caused by total diagonal artery occlusion, as demonstrated at pre-discharge coronary angiography. We aimed to assess the electrocardiographic and echocardiographic features in STEMI unequivocally attributed to a diagonal lesion in the era of primary coronary intervention.

Methods: The electrocardiograms and echocardiograms of patients sustaining STEMI caused by diagonal artery involvement were compared with those of patients with STEMI attributed to proximal or mid left anterior descending artery (LAD) lesions. ST-segment deviations were measured at four different points in each lead and analyzed against TIMI flow and SNuH score. The electrocardiographic and echocardiographic features of each group were mapped.

Results: In contrast to previous studies claiming an ever-present incidence of at least 1-mm ST-segment elevation in leads I and aVL with diagonal STEMI, we report 86% of any ST-elevation in leads I, aVL and V2 (64-71% for ST-elevation >1 mm). Both higher SNuH score and pre-intervention TIMI flow were associated with larger lateral ST-elevations (85.7% and 86.4-95.5%, respectively). Higher prevalence of ST-depression in the inferior leads reflecting reciprocal changes was observed in patients with diagonal-induced STEMI (57-76% . 24-51% in LAD obstructions, <0.05).

Conclusion: The most sensitive and predictive sign for acute ischemia was any degree of ST-deviation measured 1 mm beyond the J point. ST-elevations in I, aVL and V, sparing V-V, strongly favor isolated diagonal lesion. Proximal LAD lesion lacking ST-segment elevations in leads I and aVL is primarily due to wraparound LAD anatomy.