Abstract
BackgroundThe assessment of post-myocardial infarction (MI) left ventricular (LV) remodeling by cardiovascular magnetic resonance (CMR) currently uses criteria defined by echocardiography. Our aim was to provide CMR criteria for assessing LV remodeling following acute MI.MethodsFirstly, 40 reperfused ST-segment elevation myocardial infarction (STEMI) patients with paired acute (4 ± 2 days) and follow-up (5 ± 2 months) CMR scans were analyzed by 2 independent reviewers and the minimal detectable changes (MDCs) for percentage change in LV end-diastolic volume (%ΔLVEDV), LV end-systolic volume (%ΔLVESV), and LV ejection fraction (%ΔLVEF) between the acute and follow-up scans were determined. Secondly, in 146 reperfused STEMI patients, receiver operator characteristic curve analyses for predicting LVEF <50% at follow-up (as a surrogate for clinical poor clinical outcome) were undertaken to obtain cut-off values for %ΔLVEDV and %ΔLVESV.ResultsThe MDCs for %ΔLVEDV, %ΔLVESV, and %ΔLVEF were similar at 12%, 12%, 13%, respectively. The cut-off values for predicting LVEF < 50% at follow-up were 11% for %ΔLVEDV on receiver operating characteristic curve analysis (area under the curve (AUC) 0.75, 95% CI 0.6 to 0.83, sensitivity 72% specificity 70%), and 5% for %ΔLVESV (AUC 0.83, 95% CI 0.77 to 0.90, sensitivity and specificity 78%). Using cut-off MDC values (higher than the clinically important cut-off values) of 12% for both %ΔLVEDV and %ΔLVESV, 4 main patterns of LV remodeling were identified in our cohort: reverse LV remodeling (LVEF predominantly improved); no LV remodeling (LVEF predominantly unchanged); adverse LV remodeling with compensation (LVEF predominantly improved); and adverse LV remodeling (LVEF unchanged or worsened).ConclusionsThe MDCs for %ΔLVEDV and %ΔLVESV between the acute and follow-up CMR scans of 12% each may be used to define adverse or reverse LV remodeling post-STEMI. The MDC for %ΔLVEF of 13%, relative to baseline, provides the minimal effect size required for investigating treatments aimed at improving LVEF following acute STEMI.
Highlights
The assessment of post-myocardial infarction (MI) left ventricular (LV) remodeling by cardiovascular magnetic resonance (CMR) currently uses criteria defined by echocardiography
The basal cine slice was included if at least 50% of the cavity circumference was surrounded by ventricular myocardium and this principle was used for both end-systole and end-diastole. %ΔLVEDV, %ΔLVESV, %ΔLVM and %ΔLVEF were calculated as the difference between the follow-up parameters and the corresponding baseline parameters and expressed as a percentage of the baseline parameters
Comparison of Coefficient of variation (CoV) did not show any statistical difference for inter-observer or intra-observer measurements (LVEDV, LV end-systolic volume (LVESV), LVM, LV ejection fraction (LVEF)) on both the acute or follow-up scans between both LV quantification methods (T&P included as part of the LV volume or LV mass) (P values between 0.15 and 0.97)
Summary
The assessment of post-myocardial infarction (MI) left ventricular (LV) remodeling by cardiovascular magnetic resonance (CMR) currently uses criteria defined by echocardiography. Despite prompt reperfusion of acute ST-elevation myocardial infarction (STEMI) by primary percutaneous coronary intervention (PPCI), adverse left ventricular (LV) remodeling still occurs in a significant proportion of patients [1], and its presence predisposes to heart failure [2] and worse clinical outcomes [3]. Adverse LV remodeling following STEMI has been conventionally defined as ≥ 20% increase in LV end-diastolic volume (LVEDV) from baseline This cut-off value was determined using echocardiography, and was based on the upper limit of the 95% confidence interval of intraobserver variability for the percentage change (%Δ) in LVEDV following STEMI [8, 9]. No cut-off values for adverse and reverse LV remodeling following STEMI have been defined by CMR, and studies using CMR to assess post-STEMI LV remodeling have relied upon using these cut-off values defined by echocardiography for adverse [11, 12] and reverse LV remodeling [13]
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