Abstract
BackgroundAlthough echocardiography is commonly used to evaluate cardiac function after MI, CMR may provide more accurate functional assessment but has not been adequately compared with echo. The primary study objective was to compare metrics of left ventricular volumes and global and regional function determined by cardiac magnetic resonance (CMR) and echocardiography (echo) in patients (pts) with recent myocardial infarction (MI).MethodsTo compare CMR with echo, 47 consecutive patients (pts 70% male; mean age = 66 ± 11 years) with MI >6 wks previously and scheduled for imaging evaluation were studied by both echo and CMR within 60 min of each other. Readers were blinded to pt information. Pearson's correlation coefficient, paired t-tests, and chi-square tests were used to compare CMR and echo measures. Further comparisons were made between pts and 30 normal controls for CMR and between pts and published normal ranges for echo.ResultsMeasures of volume and function correlated moderately well between CMR and echo (r = 0.54 to 0.75, all p < 0.001), but large and systematic differences were noted in absolute measurements. Echo underestimated left ventricular (LV) volumes (by 69 ml for end-diastolic, 35 ml for end-systolic volume, both p < 0.001), stroke volume (by 34 ml, p < 0.001), and LV ejection fraction (LVEF) (by 4 percentage point, p = 0.02). CMR was much more sensitive to detection of segmental wall motion abnormalities (p < 0.001). CMR comparisons with normal controls confirmed an increase in LV volumes, a decrease in LVEF, and preservation of stroke volume after MI.ConclusionThis intra subject comparison after MI found large, systematic differences between CMR and echo measures of volumes, LVEF, and wall motion abnormality despite moderate inter-modality correlations, with echo underestimating each metric. CMR also provided superior detection and quantification of segmental function after MI. Serial studies of LV function in individual patients should use the same modality.
Highlights
Echocardiography is commonly used to evaluate cardiac function after myocardial infarction (MI), cardiac magnetic resonance (CMR) may provide more accurate functional assessment but has not been adequately compared with echo
Study Objectives The main study objectives were: 1) to determine and compare metrics of left ventricular volumes and function between CMR and echo in a consecutive cohort of post-MI patients presenting for imaging evaluation of cardiac function, 2) to compare the sensitivity of the 2 modalities to assess regional wall motion (RWM) after MI, and 3) to quantitatively assess changes in these parameters after MI by a comparison of study patients with a cohort of normal volunteers
The CMR control group included 30 healthy volunteers (15 women, 15 men) of average age 47 years with average body surface area (BSA) 1.7 sq m in women and 2.1 sq m in men
Summary
Echocardiography is commonly used to evaluate cardiac function after MI, CMR may provide more accurate functional assessment but has not been adequately compared with echo. Cardiac magnetic resonance (CMR) is increasingly utilized for dynamic imaging of the heart with the expectation that it will provide more accurate and reproducible measurements of cardiac chamber dimensions, volumes, and function compared to other non-invasive imaging techniques such as echocardiography and nuclear cardiography [1,2,3]. This expectation arises from the superior spatial resolution and more precise border definition achieved with CMR compared with these other techniques. We undertook an intra subject comparison of echo with CMR in a consecutive cohort of post-MI patients to determine correlations and systematic differences between these modalities in assessing left ventricular volumes and function
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