Patient: 56-year-old man, hypertensive, smoker, hospitalized at H + 4 for typical chest pain; entry ECG;
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Inferior infarction due to right coronary thrombosis
ECG : Sinus rhythm, normal PR interval; elevation in the inferior leads, with higher amplitude of the elevation in lead III versus lead II; deep reciprocal depression in aVL and V2;
ECG 2: Recording of right and posterior leads; absence of right ventricular or posterior wall extension;
Comments: This patient presented an acute coronary syndrome due to thrombosis of the second segment of the right coronary artery. In an inferior infarction, coronary angiography can reveal a lesion of the right coronary artery or of the circumflex artery. Numerous studies have investigated the value of the surface electrocardiogram in quickly locating the artery responsible for symptomatology and guide the interventional cardiologist. The site of the lesion also modifies the prognosis, the demonstration of a right ventricular extension, for example, having significant consequences on therapeutic treatment and on the stratification of risk. The sensitivity and specificity of the various electrocardiographic parameters or of the algorithms proposed in the literature appear relatively limited however, due to the high inter-individual variability of the coronary artery (anatomical variations, history of bypass surgery, collateral branch development, etc.). The comparison between the elevation amplitudes in leads III and II, the amplitude of the depression in aVR, V1, lead I or aVL, a possible right ventricular extension have been used as standalone or in various algorithms. Indeed, an occlusion of the right coronary results in an activation vector directed inferiorly and to the right whereas during a circumflex occlusion, the vector is directed more to the left and posteriorly (directly in the direction of lead II), which explains why the amplitude of the elevation is higher in lead III than in lead II for a right thrombosis and vice versa for a circumflex occlusion. The reciprocal trace will be preferentially observed in lateral leads for the right coronary artery and toward aVR for the circumflex artery. As explained previously, there are, however, numerous anatomical differences between patients which can limit the ability to accurately locate the culprit artery: different positions of the heart in the thorax, the right coronary artery or circumflex artery may be more or less dominant thereby altering the area of the targeted territory, the posterolateral branches supplying the left ventricular inferolateral wall can originate from the right coronary artery or the circumflex artery, etc.
In spite of the aforementioned limitations, certain signs allow evoking the culprit artery responsible for the clinical picture: 1) a higher elevation amplitude in lead III compared to lead II is indicative of a right coronary artery disease and vice versa for the circumflex artery; 2) a depression in lead I is in indicative of a right coronary artery disease whereas an elevation rather suggests a circumflex artery disease; 3) a greater depression amplitude in aVL than in lead I points to the right coronary artery; 4) when the sum of the elevation in V1, V2, V3 is greater than that of leads II, III and aVF, a circumflex artery involvement is likely and inversely for the right coronary artery; 5) a significant depression in V1, V2, V3 or in the right leads is evocative of a circumflex thrombosis; 6) a significant depression in aVR rather points to a circumflex disease; 7) a decrease in the amplitude of the R wave with an increase in the S wave in aVL with an S/R wave ratio > 1/3 points to a right coronary disease; 8) a right ventricular extension (V4R elevation) points to a proximal right coronary disease.
Take-home message: Various electrocardiographic parameters have been proposed to differentiate a right coronary thrombosis and a circumflex thrombosis in the setting of an inferior infarction. Due to anatomical differences between patients, each parameter taken individually has limited sensitivity and specificity.
What is(are) the possible diagnosis(es) on this ECG?CorrectIncorrect