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Published on: December 11, 2016
Relation between infarct size in ST-segment elevation myocardial infarction treated successfully by percutaneous
Yuri B Pride1, Jennifer L Giuseffi, Satishkumar Mohanavelu
1Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
Insights
For moderate to large ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI), larger infarct size significantly reduces left ventricular ejection fraction (LVEF). Small infarcts show no significant impact on LVEF.
Area of Science:
- Cardiology
- Cardiovascular Imaging
- Myocardial Infarction
Background:
- Left ventricular ejection fraction (LVEF) and infarct size are crucial prognostic indicators after ST-segment elevation myocardial infarction (STEMI).
- The precise relationship between infarct size and LVEF following primary percutaneous coronary intervention (pPCI) requires further elucidation.
Purpose of the Study:
- To investigate the correlation between myocardial infarct size and LVEF in STEMI patients post-pPCI.
- To define the threshold of infarct size impacting LVEF.
Main Methods:
- Cardiovascular magnetic resonance imaging (CMR) was employed to assess LVEF and infarct size.
- Late gadolinium enhancement CMR quantified infarct size as a percentage of LV myocardial volume.
- Cine imaging calculated LVEF using the volumetric summation of disks method.
Main Results:
- In patients with infarct size ≥15%, a significant negative linear association was observed between infarct size and LVEF (slope -1.21, R²=0.66, p<0.001).
- For every 5% increase in infarct size, LVEF decreased by 6.1% in this group.
- Patients with small infarcts (<15%) maintained LVEF >40% with no significant correlation between infarct size and LVEF (p=0.13).
Conclusions:
- A negative linear relationship exists between infarct size and LVEF for moderate to large infarcts after STEMI and pPCI.
- Left ventricular ejection fraction remains largely preserved until infarct size reaches approximately 15% of LV myocardial volume.
Abstract:
The goal of this analysis was to determine the relation between myocardial infarct size and left ventricular (LV) ejection fraction (EF) in patients with ST-segment elevation myocardial infarction (STEMI) after primary percutaneous coronary intervention (pPCI) using cardiovascular magnetic resonance imaging (CMR). After STEMI, LVEF and infarct size correlate with prognosis, but the relation between infarct size and LVEF is incompletely known. Consecutive subjects presenting to a single center with STEMI treated with pPCI were enrolled, and cine functional and late gadolinium enhancement CMR was performed 3 months after presentation. From cine images, LVEF was calculated using volumetric summation of disks method. Infarct size was measured as percent LV myocardial volume with late gadolinium enhancement. In the 78 patients enrolled (mean age 54.5 years, range 42 to 82), median LVEF was 56% (interquartile range 49 to 62) and median infarct size was 11% (interquartile range 5 to 18). Of the 53 patients with infarct size <15%, all had LVEF >40%, and there was no significant relation between infarct size and LVEF (slope -0.43, R(2) = 0.045, p = 0.13). In patients with infarct size > or =15%, there was a significant negative linear association between infarct size and LVEF (slope -1.21, R(2) = 0.66, p <0.001), such that for every 5% increase in infarct size, there was a 6.1% decrease in LVEF. In conclusion, there is a negative linear relation between infarct size and LVEF for moderate to large infarcts. For small infarcts there is no significant relation between infarct size and LVEF. Up to 15% of LV myocardial volume may be infarcted before there is any appreciable decrease in LVEF.
