From the Guidelines
Left elevation, in the context of electrocardiography, is most commonly associated with occlusion of the left anterior descending coronary artery, resulting in ST-segment elevation in leads I, aVL, and V1 through V4, and reciprocal ST-segment depression in leads II, III, and aVF, as noted in the study by 1. The causes of left elevation can be understood by analyzing the spatial vector of the ST segment, which is directed to the left and laterally in the case of anterior wall ischemia/infarction. Key points to consider include:
- The location of the occlusion within the left anterior descending coronary artery, whether proximal or distal, influences the leads in which ST-segment elevation occurs and the presence of ST-segment elevation or depression in other leads, as discussed in 1.
- Proximal occlusions tend to involve the basal portion of the left ventricle, anterior and lateral walls, and interventricular septum, leading to ST-segment elevation in leads V1 through V4, I, aVL, and often aVR, with reciprocal ST-segment depression in leads II, III, and aVF, as outlined in 1.
- The use of right-sided chest leads, such as VR and V4R, can help diagnose right ventricular involvement in inferior wall infarction and distinguish between occlusions of the right coronary artery and left circumflex coronary artery, as recommended by 1. In clinical practice, recognizing the patterns of ST-segment elevation and depression is crucial for diagnosing the cause and location of myocardial ischemia or infarction, guiding immediate management and potentially improving outcomes, as emphasized by the findings in 1 and 1.
From the Research
Causes of Left Elevation
- The causes of left elevation, also known as left ventricular elevation, can be related to various cardiac conditions, including myocardial infarction (MI) and unstable angina pectoris/non-ST-segment elevation myocardial infarction 2, 3.
- In patients with suspected acute MI, elevation of a marker of myocardial necrosis, such as troponin T or I, together with ischemic symptoms and/or ischemic ECG changes, is mandatory for diagnosis 2.
- The introduction of prehospital ECG recordings and prehospital administration of thrombolytic treatment in case of ST-segment elevation MI has been shown to decrease the time from onset of symptoms till treatment considerably, which also translates into saved lives 2.
- Patients without ST-segment elevation on admission require repeated measurements of markers of myocardial damage, which, together with other biochemical markers, are useful for risk assessment 2.
- An elevated troponin concentration is shown to identify patients who benefit from antithrombotic therapy and invasive procedures 2.
- The use of aspirin and clopidogrel in combination has been shown to be effective in reducing the occurrence of re-thrombosis after percutaneous coronary intervention (PCI) and improving the recovery of cardiac function after acute operation 4, 5.
- The addition of clopidogrel to aspirin in patients with acute MI has been shown to safely reduce mortality and major vascular events in hospital 5.
- Poor response to clopidogrel is an independent predictor of periprocedural myocardial infarction and worse 1-year outcome in low-risk patients undergoing PCI 6.