ST-Segment Elevation Myocardial Infarction with Right Bundle Branch Block: Potential of New Echocardiographic Diagnostic Approaches

The article presents a clinical case of a patient with previously diagnosed right bundle branch block hospitalized with a diagnosis of non-ST-segment elevation acute coronary syndrome (NSTE-ACS). The ECG on admission showed complete right bundle branch block and first-degree atrioventricular (AV) block. The patient underwent transthoracic echocardiography (EchoCG) and speckle-tracking (ST) echocardiography to assess longitudinal strain and left ventricular myocardial work (LVMW): myocardial work index (MWI), constructive work, wasted work, and myocardial work efficiency (MWE). According to standard echocardiography, the left ventricular ejection fraction (LVEF) was 45%, with local contractility disorders in the anteroseptal region. These data were complemented by a decrease in the global longitudinal strain index (GLS = -14.2%), a decrease in regional peak systolic longitudinal strain values ≥-14%, a decrease in the area of the pressure-strain loops with their shift and slight inclination to the right, characteristic of ischemia, and a decrease in global and segmental LV MWI and MWE values in the LV anteroseptal region at all levels. Further examination revealed an increase in troponin I to 3.5 ng/ml. Coronary angiography (CAG) revealed subocclusion of the anterior interventricular branch in the proximal third; transluminal balloon angioplasty with stenting was performed. The following day, a control coronary angiography (CAG) was performed due to ST-segment elevation in the chest leads. The previously inserted stent showed no signs of thrombosis. The diagnosis was updated to "acute myocardial infarction with ST-segment elevation." A CAG echocardiogram (EchoCG) with LV MRI showed some improvement, confirming the findings of the control CAG.
Given the limited information provided by ECG diagnostics, determining the parameters of global and regional longitudinal strain and LV MRI allowed us to clarify the extent of myocardial damage, reduce the delay in invasive diagnosis and treatment, and evaluate the results over time.

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