Hints in electrocardiography for coming myocardial infarction.

Dear Editor,

The electrocardiogram (ECG) is a simple and non-invasive bedside diagnostic tool. Inversion of the T wave is a common electrocardiographic abnormality and can be interpreted as non-specific. Knowing the early changes in ECG for ischemia is crucial for the timely diagnosis of myocardial ischemia. Here, we present a 54-year-old woman admitted to the emergency department (ED) who had a normal ECG initially, which progressed with T inversions in leads aVL and V2 and resulted in inferior ST-elevated myocardial infarction (STEMI).

She was admitted to the ED with complaints of sweating, discomfort and palpitation for two hours. Her blood pressure was 130/80 mmHg and pulse was 98/min, with 98% saturation using a pulse oximeter; her physical examination was normal. The patient was monitored, an ECG was taken, intravenous access was established, and blood samples were obtained for hemogram and routine chemical tests. Her initial ECG was completely normal [Figure 1]. Twenty minutes after her admission, she described a new onset of pain in her left axillary region. A new ECG was obtained and showed T wave inversions at derivations aVL and V2, which were different from her initial ECG [Figure 2]. Fifteen minutes later, the patient started to sweat and described her pain spreading to her chest and left arm. A new ECG was obtained and ST-segment elevations at derivations D2, D3 and aVF, and reciprocal changes at aVL, V1 and V2 were present [Figure 3]. The patient was given intravenous thrombolytic therapy in the ED and was admitted to our cardiology intensive care unit. Coronary angiography was performed 24 hours later. There was stenosis in the proximal left main coronary artery (70%) and right coronary artery (85% and 90%) and total occlusion in the left anterior descending artery (LAD) [Figures 4 and 5]. Emergent coronary artery bypass grafting operation was planned and she was transferred to the cardiovascular surgery clinic.

Figure 1

The first normal electrocardiogram of the patient

Figure 2

T wave inversions in leads aVL and V2 were present in the second electrocardiogram, which was obtained 20 minutes after the patient's admission

Figure 3

ST-segment elevations at derivations D2, D3 and aVF, and reciprocal changes at aVL, V1 and V2 were present in the third electrocardiogram, which was obtained 35 minutes after the patient's admission

Figure 4

The stenosis in the proximal left main coronary artery and total occlusion in the left anterior descending artery are visible on coronary angiogram

Figure 5

The stenosis in the right coronary artery is visible on coronary angiogram

In the setting of acute coronary syndrome, several ECG findings help to localize the occluded vessel and occlusion site.[12] Certain T wave abnormalities in precordial leads are early warnings for an MI. Either the positive-negative biphasic T waves or the deeply inverted T waves that often follow them, when occurring in the precordial leads, are nearly pathognomonic of very recent severe ischemia or injury in the distribution area of the LAD and characterize Wellens syndrome.[3] T wave inversion in aVL significantly predicts LAD lesions typically in the mid-segment.[4] This finding should alert the health care providers during ECG interpretation.

ST elevation in V5 and V6 are associated with large-vessel occlusion, larger infarct size and ST depression, while flat T waves in these leads indicate the probability of three-vessel disease in inferior STEMI patients.[5]

Our case shows that T wave inversions in leads aVL and V2, which can be thought of as non-specific may be a predictor of the following inferior MI. Observation of the patient and obtaining serial ECGs are important for not overlooking a myocardial ischemia developing into infarction.