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Return of left ventricular function after reperfusion in patients with myocardial infarction: importance of subtotal
Insights
Pre-intervention coronary arteriography can predict left ventricular ejection fraction improvement after acute myocardial infarction. Patients with limited blood flow to the infarct zone show better recovery, especially with successful reperfusion.
Area of Science:
- Cardiology
- Interventional Cardiology
- Myocardial Infarction Research
Background:
- Left ventricular ejection fraction (LVEF) is a key indicator of cardiac function post-myocardial infarction (MI).
- Predicting LVEF recovery is crucial for guiding treatment strategies and patient prognosis.
Purpose of the Study:
- To assess if pre-intervention coronary arteriography findings can predict subsequent LVEF improvement in acute MI patients.
- To identify factors influencing LVEF changes following early reperfusion interventions.
Main Methods:
- 63 acute MI patients were categorized into 'no-flow' (occluded artery, no collaterals) and 'limited-flow' (subtotal stenosis/occlusion with collaterals) groups.
- Emergency coronary arteriography was performed at a mean of 7 hours post-symptom onset.
- Reperfusion procedures were undertaken in 61 patients, with LVEF assessed at baseline and follow-up angiography (12 days post-MI).
Main Results:
- Significant LVEF improvement occurred in the 'limited-flow' group with successful reperfusion, driven by regional improvement in the infarct zone.
- LVEF significantly decreased in the 'no-flow' group with unsuccessful reperfusion, due to reduced function in the non-infarct zone.
- No significant LVEF changes were observed in 'no-flow' with successful reperfusion or 'limited-flow' with unsuccessful reperfusion groups.
- Reperfusion timing did not significantly correlate with LVEF changes.
- Greater LVEF improvement was noted in anterior MIs compared to inferior MIs.
Conclusions:
- In acute MI, preserved flow to the infarct zone (even with collaterals) is essential for LVEF improvement post-reperfusion.
- Successful reperfusion in the absence of pre-existing flow to the infarct area is unlikely to restore LVEF.
- Patients with limited infarct artery flow demonstrate favorable LVEF recovery, particularly with successful intervention.
- Initial severity of LVEF depression may influence the magnitude of observed improvement.
Abstract:
To determine whether subsequent improvement in left ventricular ejection fraction can be predicted from preintervention coronary arteriograms, we divided 63 patients with acute myocardial infarction into two groups based on findings at emergency coronary arteriography at a mean of 7 hr after onset of symptoms: (1) a "no-flow" group with an occluded infarct-related artery and no easily visible collaterals (n = 36) and (2) a "limited-flow" group with either subtotal stenosis or total occlusion of the infarct-related vessel with intact collaterals (n = 27). Of the 63 patients, 61 underwent emergency procedures to establish reperfusion. At follow-up angiography (contrast or radionuclide) performed 12 +/- 7 days after infarction, global ejection fraction had increased significantly in patients with limited flow to the infarct zone and "successful" early reperfusion intervention due primarily to a significant increase in the regional ejection fraction in the infarct zone. Global ejection fraction fell significantly between baseline and follow-up in patients with no flow to the infarct zone and "unsuccessful" early reperfusion intervention due primarily to a fall in the regional ejection fraction of the noninfarct zone. Global and regional ejection fractions did not change significantly in patients with no flow to the infarct zone and successful early reperfusion or in patients with limited flow to the infarct zone and unsuccessful early reperfusion intervention. The elapsed time before reperfusion did not relate significantly to the change in either regional or global ejection fraction. However, the magnitude of improvement in both global and regional ejection fraction at follow-up was greater among patients with anterior infarcts than among those with inferior infarcts, possibly because baseline ejection fraction was lower in patients with anterior infarcts. These data indicate that among patients with acute myocardial infarction undergoing emergency coronary arteriography at a mean of 7 hr after onset of symptoms, improvement in global ejection fraction is unlikely to occur even after a successful early reperfusion intervention in the absence of preserved flow to the infarct area. However, among patients with subtotally occluded infarct-related arteries or significant collateral blood flow to the infarct zone, subsequent improvement in global and regional ejection fraction in the zone of myocardial infarction frequently occurs. Improvement in both global and regional ejection fraction may be more readily demonstrated in patients initially having more severe depression of these parameters.