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Extension of hypokinesia into angiographically perfused myocardium in patients with acute infarction
P J Ahrens1, F H Sheehan, J vom Dahl
1University of Washington, Seattle 98195.
Insights
Assessing the extent of left ventricular hypokinesia after myocardial infarction (MI) is crucial. This study found that hypokinesia often extends beyond the infarct-related artery, making coronary angiography an inaccurate measure of the risk region size in acute MI patients.
Area of Science:
- Cardiology
- Medical Imaging
- Myocardial Infarction Research
Background:
- Accurate infarct size measurement is vital for experimental studies.
- Regional hypokinesia variability in acute myocardial infarction (MI) can be reduced by assessing the at-risk region.
- Coronary angiography is a key diagnostic tool in evaluating patients with acute MI.
Purpose of the Study:
- To determine if left ventricular hypokinesia in acute myocardial infarction (MI) is confined to the region between the coronary artery occlusion site and the artery's distal end.
- To evaluate the accuracy of coronary angiography in defining the infarct-related risk region.
- To investigate the extent of myocardial dysfunction in relation to coronary anatomy.
Main Methods:
- Analysis of angiograms from 84 patients with acute myocardial infarction (MI) caused by isolated stenosis of the right coronary artery or left anterior descending coronary artery.
- Determination of hypokinetic segment length (<-1 or -2 SD below normal) using the centerline method.
- Definition of the risk region as the left ventricular contour from the occlusion site to the infarct-related artery's end.
Main Results:
- Hypokinesia exceeding the defined risk region occurred in 52% of left anterior descending coronary artery occlusions versus 22% of right coronary artery occlusions (p < 0.01).
- Severe hypokinesia (<-2 SD) extended beyond the risk region in 33% of anterior infarcts and 9% of inferior infarcts.
- These findings indicate frequent extension of myocardial dysfunction beyond the territory supplied by the occluded artery.
Conclusions:
- Coronary angiography provides an inaccurate assessment of the true size of the myocardial risk region in patients with acute myocardial infarction (MI).
- The extent of left ventricular hypokinesia frequently surpasses the anatomical boundaries defined by coronary angiography.
- Further research is needed to develop more accurate methods for quantifying infarct size and at-risk myocardium.
Objective:
This study was performed to determine whether left ventricular hypokinesia due to acute myocardial infarction lies between the site of coronary artery occlusion and the end of the infarct-related artery in patients.
Background:
Normalizing for the size of the risk region reduces variability in measuring infarct size in experimental studies. The ability to gauge the size of the region at risk of becoming dysfunctional may help reduce variability in measuring regional hypokinesia due to acute myocardial infarction.
Methods:
Angiograms of 84 patients with acute infarction due to isolated stenosis of the right coronary artery (n = 40) or the left anterior descending coronary artery (n = 44) were analyzed. The location and length of the segment with hypokinesia more severe than -1 or -2 SD below the normal mean were determined by the centerline method. The risk region was defined as the left ventricular contour between the site of the occlusion and the end of the infarct-related artery on the angiogram.
Results:
The segment with hypokinesia below -1 SD was longer than the risk region in 52% of patients with occlusion of the left anterior descending coronary artery, more frequently (p < 0.01) than in right coronary artery occlusion (22%), owing to extension of hypokinesia beyond the distal end of the artery. Extension of severe hypokinesia (below -2 SD) beyond the risk region occurred in 33% of patients with an anterior infarct and in 9% of patients with an inferior infarct.
Conclusions:
The size of the risk region cannot be assessed accurately from coronary angiography.