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Q1: Describe the ECG
The ECG shows 1 mm concave ST elevation in SII, aVF and V6, which reached 2 and 3 mm in V4 and V5, respectively. Small notches at the junctions of QRS waves and elevated ST segments are consistent with the displacement of J points (fig 1 below).
Q2: List the electrocardiographic characteristics of early repolarisation
The characteristics are: an upward concave elevation of the RS-T segment with distinct or “embryonic” J waves, slurred downstroke of R waves or distinct J points or both, RS-T segment elevation commonly encountered in the precordial leads and more distinct in these leads, rapid QRS transition in the precordial leads with counterclockwise rotation, and persistence of these characteristics for many years, although some intraindividual changes are common. Less commonly found are: tall R and T waves in the precordial leads, “labile” or “juvenile” T wave patterns, “pseudo R” waves, and isolated T negativity.1
Q3: Compare the electrocardiographic features of early repolarisation, pericarditis, and myocardial infarction
ECG manifestations of acute pericarditis or ischaemia evolve in a matter of hours or days, while ECG changes in early repolarisation remain stable over an extended period. In acute myocardial infarction, the evolving ECG changes (Q wave, ST segment) are confined to the leads reflecting the area of myocardium involved with reciprocal changes in the opposite leads. In pericarditis, the ST-T changes are almost always found in precordial as well as limb leads; but in early repolarisation mostly precordial leads, or rarely limb leads, are involved. No consistent reciprocal changes of significance are to be relied upon in the latter two conditions. In early repolarisation, the axis is usually vertical and in pericarditis is horizontal. Early repolarisation shows tall, slightly asymmetrical T waves. In myocardial injury, they are tall and symmetrical. In pericarditis, the T waves are not usually tall, and in disputable cases an ST/T ratio >0.25 in V6 helps in reaching a diagnosis.2
Early repolarisation, also known as benign early repolarisation or normal variant, is noted in approximately 1% of the population and in up to 48% of patients seen in the emergency department with chest pain.3 It represents a benign variant of the normal ECG and is one of the several syndromes producing electrocardiographic ST elevation.3 It occurs almost exclusively in males under 40 years of age and is a permanent feature of their ECGs and usually disappears at older ages.4 The ECG manifestations may mimic acute myocardial injury or pericarditis. Exercise and isoproterenol tend to normalise the RS-T segment elevation. The presence of early repolarisation does not preclude diagnosis of exercise induced myocardial ischaemia by treadmill testing, and coronary vaso-occlusive lesions may be demonstrated in some patients with the early repolarisation pattern on ECG. The presence of ST elevation in a patient with chest pain of possible cardiac origin mandates hospitalisation and cardiac monitoring even if the ECG demonstrates a classic pattern of early repolarisation; in this context, the diagnosis of early repolarisation is one of exclusion.5
The initial examination of the case mentioned above represented two main characteristics: chest discomfort at rest and ST elevations consistent with early repolarisation. The patient, therefore, was transferred to our coronary care unit with the initial diagnosis of acute inferolateral myocardial injury. Myocardial necrosis was excluded with the absence of cardiac enzyme changes and typical ECG evolution of an acute myocardial infarction, and with the negative scintigraphic test result. Angina pectoris and ST elevations persisted for 20 minutes and three days, respectively. The transient nature of ECG finding excluded the diagnosis of early repolarisation. Medical therapy was ordered with the final diagnosis of coronary artery spasm and she re-transferred to the nephrology clinic in her sixth day.
Our patient was evaluated while she was followed up in hospital, therefore we had the opportunity to compare the ECG with the baseline measurements. In the majority of subjects admitted to emergency departments with any kind of chest pain, however, there is no chance of comparing the ECG with any other. In patients with chest pain a diagnosis of early repolarisation should only be considered when a cardiac cause has been excluded.
Coronary artery spasm.