New-onset extreme right axis deviation in acute myocardial infarction: clinical characteristics and outcomes

Background QRS axis deviation can occur during myocardial infarction (MI); to date, little is known about the significance of extreme right axis deviation (ERAD) in the frontal plane, i.e. a shift in QRS axis between +180° and +270°, during MI. We sought to investigate the clinical characteristics and outcomes of patients with new-onset ERAD in the absence of complete bundle branch blocks (BBB) in the setting of acute coronary syndromes (ACS). Methods A single-center retrospective observational study was conducted, including patients with new-onset ERAD in the absence of complete BBB admitted for ACS to our Cardiac Intensive Care Unit. Clinical, electrocardiographic, echocardiographic, angiographic features at baseline and cardiovascular events during hospitalization and at mid-term follow-up were collected. Results The study population consisted of 30 consecutive patients (23 men) from January 2014 to September 2018. The most frequent clinical presentation was ST-segment elevation MI (n = 22, 73.4%) and the most frequent electrocardiographic MI location was anterolateral (n = 11, 36.7%). Left anterior descending (LAD) was the most frequent infarct-related artery (n = 21, 70%); 15 patients (50%) had multivessel coronary artery disease. Cardiac arrest due to ventricular fibrillation (VF) at presentation (n = 5, 16.6%), cardiogenic shock during the hospital stay (n = 10, 33.3%), cardiac arrest due to VF after revascularization (n = 6, 20%) and cardiac death (n = 7, 23.3%) were common. Conclusion New-onset ERAD during MI may be related to extensive myocardial ischemia and/or necrosis causing an “electrical escaping” with an extreme dislocation of the QRS axis. In our limited series we found several acute arrhythmic and hemodynamic complications and high mortality.