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Myocardial infarction due to isolated left circumflex or right coronary artery occlusion
1Department of Cardiology, Ruijin Hospital, Shanghai Second Medical University.
Insights
Electrocardiogram (ECG) findings like lateral Q waves and abnormal R waves in lead V1 may indicate left circumflex (LCX) artery occlusion during myocardial infarction. These patterns are linked to poorer left ventricular function and more cardiac events.
Area of Science:
- Cardiology
- Medical Imaging
- Clinical Diagnostics
Background:
- Myocardial infarction (MI) diagnosis relies on ECG, but specific patterns for isolated coronary artery occlusions are crucial.
- Differentiating between left circumflex (LCX) and right coronary artery (RCA) related MI is important for prognosis.
Purpose of the Study:
- To assess ECG patterns in patients with first MI due to isolated LCX occlusion.
- To compare these ECG patterns with those in RCA-related MI.
- To correlate ECG findings with clinical, angiographic features, and cardiac events.
Main Methods:
- Retrospective analysis of 41 patients with LCX occlusion and 45 patients with RCA occlusion.
- Evaluation of ECG for Q waves (inferior, lateral) and abnormal R wave in lead V1.
- Assessment of left ventricular volumes, ejection fraction, and coronary angiography.
Main Results:
- Lateral Q waves and abnormal R wave in lead V1 were more frequent in LCX occlusion (46% vs 7%, 51% vs 4%).
- LCX occlusion with these ECG markers showed larger LV volumes, lower ejection fraction, and more total occlusions without collaterals.
- Patients with LCX-related MI and specific ECG markers experienced more cardiac events.
Conclusions:
- ECG lateral Q waves and abnormal R wave in lead V1 may serve as useful markers for LCX occlusion.
- Left ventricular function and outcomes in LCX-related MI vary based on collateral circulation and residual flow.
Abstract:
The electrocardiographic (ECG) patterns related to clinical spectrum and angiographic features were assessed in 41 patients with first myocardial infarction due to isolated left circumflex coronary artery (LCX) occlusion, and compared to those in 45 patients with right coronary artery (RCA)-related infarction. The occurrence of inferior Q waves was similar in patients with LCX and RCA occlusion, but lateral Q waves and an abnormal R wave in lead V1 were more frequently seen in patients with LCX-related infarction (46% vs 7% and 51% vs 4%, respectively). Compared with patients with LCX-related infarction without an abnormal R wave in lead V1 and those with RCA occlusion, patients with LCX-related infarction and an abnormal R wave in lead V1 associated with inferior and/or lateral Q waves had larger left ventricular end-diastolic and end-systolic volumes, lower ejection fraction, higher incidence of total occlusion of a dominant LCX without collaterals, and more cardiac events during follow-up. The study suggests that the presence of lateral Q waves and an abnormal R wave in lead V1 after myocardial infarction may be a useful marker of LCX occlusion, and that patients with LCX-related infarction may have different status of left ventricular function depending on the size of circulation and the status of residual flow to the infarct region during LCX occlusion.